JPH0668596B2 - Zoom lens barrel - Google Patents

Description

TECHNICAL FIELD The present invention relates to a zoom lens barrel, and more particularly to a zoom lens barrel having a function of correcting the aperture diameter in association with a change in focal length due to zooming.

(Prior Art) In terms of optical design, a zoom lens barrel whose open F value changes by zooming does not have a correction mechanism.
A constant value, the aperture diameter changes due to zooming during open metering, but a constant F value when the aperture is narrowed down, and correction is performed by the aperture value transmission member during open metering (actual opening 53-8226, JP-A-56-
No. 155908) is considered.

However, in the above zoom lens barrel, since the scale of the diaphragm ring has an F value at a certain focal length, an accurate F value cannot be read at other focal lengths. That is, even if the exposure is determined with a meter in the viewfinder, the exposure must be determined again after zooming. Further, in a combination with a camera body having an AE lock or the like, if the zooming operation is performed after the AE lock by photometry, the F value will change and the exposure value will change. In particular, in the case of spot metering storage, even if the metering is accurately performed on the telephoto side, there are many cases in which the subject is subsequently zoomed to the wide-angle side for shooting, which is very inconvenient.

Further, in the case of the lens barrel of the zoom lens described above, the bright F value area on the wide angle side, which can be sufficiently used in terms of optical design, is used by narrowing it down to an F value equal to or larger than the open F value on the telephoto side. There is a problem in that the part where focusing is easy is sacrificed.

Further, in the above zoom lens barrel, when the AE lock operates following the shutter dial and the aperture value transmission member, as an example, the open F value is F4 at the telephoto side and F2.8 at the wide angle side at F2.8. If the set aperture value by the aperture ring is set to F5.6 and the AE lock is performed on the telephoto side by using the lens of, the aperture value transmission member is located at the position of F5.6. Here, when zooming to a wide angle state, the open F value is F2.
The aperture value transmission member moves to a position corresponding to F8 on the telephoto side. Since the aperture ring is at F5.6,
When the shutter is released, the aperture will be stopped down to the aperture of F5.6 in the wide-angle state, but since the camera operates based on the information on the telephoto side, the shutter speed will be the value at F8.
There was a problem that EV was overexposed.
There is also a problem that the maximum open F value is regulated, as in the above case.

(Purpose) In view of the above points, an object of the present invention is to provide a zoom lens barrel which has a correction function of making the open F-number constant during zooming and can set the open F-number specific to the lens. To provide.

(Outline) In the zoom lens barrel of the present invention, the open F value is not constant in terms of optical design due to zooming. In the zoom lens barrel, the aperture F value is fixed by mechanically changing the aperture diameter during zooming. Aperture correction so that
When the aperture ring is adjusted to the wide-angle side open F value, the function of the aperture correction that keeps the open F value constant is canceled.

(Example) Hereinafter, the present invention will be described based on illustrated examples.

FIG. 1 is a sectional view of a zoom lens barrel showing an embodiment of the present invention. In this zoom lens barrel, a fixed frame 2 is fixed to a lens mount 1 that engages with a bayonet mount (not shown) on the camera body side, and an aperture ring 4 is rotatably fitted to the fixed frame 2. Outer frame 3 supported together
Is fixed. On the outer periphery of the outer frame 3, a set ring 5
Is rotatably fitted, and a zoom ring 6 is fitted and fixed to the outer periphery of the set ring 5. A cam ring 8 having a cam groove (not shown) for moving the first lens group 41 and the second lens group 42 is freely rotatable between the fixed frame 2 and the outer frame 3. Is fitted to.
A zoom pin 7 is fixed to the cam ring 8, and the zoom pin 7 penetrates the groove of the outer frame 3 to set the ring 5.
It is fitted in the groove provided in the and fixed to the set ring 5 and the zoom ring 6.

An aperture frame 16 and an outer helicoid frame 25 are slidably fitted on the inner circumference of the fixed frame 2. A roller 18 is provided on the outer periphery of the diaphragm frame 16.
The roller shaft 17 having the above is planted. The roller 18 is fitted into a straight groove formed in the fixed frame 2 and a cam groove formed in the cam ring 8, and the rotation of the zoom ring 6 causes the cam ring 8 to rotate via the zoom pin 7. Then, the diaphragm frame 16 slides in the front-rear direction. An automatic diaphragm mechanism 34 is arranged on the diaphragm frame 16, and a blade holding frame 19 to which the second lens group 42 is fixed and a rear frame 33 are fixed.

A pin 26 is planted on the outer circumference of the outer helicoid frame 25. The pin 26 is fitted in a cam groove formed in the fixed frame 2 and the cam ring 8, and is rotated by the zoom ring 6. When the cam ring 8 rotates, this causes the outer helicoid frame 25 to slide in the front-rear direction. An inner helicoid frame 27 is screwed onto the inner circumference of the outer helicoid frame 25 by means of a helicoid screw formed between the inner helicoid frame 27 and the inner helicoid frame.
A front frame 35 to which the first lens group 41 is fixed is attached to the inner circumference of 27. Further, the inner helicoid frame 27 is screwed and fixed to the filter frame 28 which is integral with the distance ring 29 rotatably fitted to the outer periphery of the cam ring 8, and when the distance ring 29 rotates, the The filter frame 28 and the inner helicoid frame 27 are integrally rotated to move the first lens group 41 in the front-rear direction.

A diaphragm value setting member 9 is fixed to the diaphragm ring 4. The aperture value setting member 9 has a connecting portion 9a extending rearward in parallel with the optical axis O and a cam rotating portion 9b extending forward.
The connecting portion 9a is a notch groove 14 of an aperture value transmission interlocking plate 14 that is rotatably fitted to a cover frame 13 that fixes the third lens group 43 inside the lens mount 1 by a stop ring 15.
The cam rotation part 9b is fitted in the a
It is engaged with the notch 22c of the aperture cam plate 22 for determining the aperture diameter of 4 (see FIG. 2). Further, the cam rotating portion 9b has a shape inclined from the base portion to the tip end thereof at the angle θ ₁ in the clockwise direction (see FIG. 3). The interlocking plate 14 extends rearward and has an arcuate groove 13a (second and second grooves) formed in the cover frame 13.
A body interlocking portion 14b is provided, which protrudes from the camera main body side (see FIG. 6) and can engage with the interlocking member on the camera main body side. A spring 31 is hung between the connecting portion 9a of the aperture value setting member 9 and the interlocking plate 14, and the interlocking plate 14 is moved clockwise by the tensile force of the spring 31 (when viewed from the front of the lens barrel, Similarly, the notch groove 14a of the interlocking plate 14 is biased by
One end 14a ₀ thereof (see FIG. 2) is in contact with the connecting portion 9a.

The aperture ring 4 is provided with a spring 10a provided on the fixed frame 2 and a click ball 10b pressed by the spring 10a, and an index 32 (see FIG. 2) imprinted on the outer periphery of the fixed frame 2 and an aperture value on the aperture ring 4. Click stop is made at the position where the scale matches. A ring-shaped stop plate 11 is fixed between the lens mount 1 and the fixed frame 2, and a stop transmission member 12 is rotatably fitted between the stop plate 11 and the lens mount 1. There is. The aperture transmission member 12 has an engaging portion 12a extending rearward in parallel with the optical axis O and an aperture plate rotating portion 12b extending forward. The engaging portion 12a projects inside the lens mount 1 from an arcuate groove formed in the cover frame 13 toward the camera body side and engages with a diaphragm drive lever (not shown) on the camera body side. The diaphragm plate rotating portion 12b is a cutout portion 2 of the diaphragm plate 23 of the automatic diaphragm mechanism 34.
It is engaged with 3c (see Fig. 2). Further, the diaphragm plate rotating portion 12b has a shape inclined from the base portion to the front end at an angle θ ₂ in the clockwise direction (see FIG. 4). A spring 30 is urged between the narrowing transmission member 12 and the stop plate 11 for urging the narrowing transmission member 12 in a direction to open the diaphragm blades 20 of the automatic diaphragm mechanism 34.

An automatic diaphragm mechanism 34 is provided between the blade holding frame 19 and the diaphragm frame 16.
The diaphragm blade 20 and the arrow wheel 21 are provided. The structure of the automatic diaphragm mechanism 34 is shown in FIG. 2 in an exploded perspective view in which it is enlarged. Six diaphragm blades 20 are provided (only one is shown in FIG. 2), and a support hole 20b serving as a fulcrum of rotation of each blade 20 is fitted to a pin 16b of the diaphragm frame 16. At the same time, the locking pin 20a is engaged with each notch 21b formed in the inner circumference of the arrow wheel 21, which is rotatable around the optical axis O. A spring 36 is provided between the arrow wheel 21 and the diaphragm frame 16 so as to constantly apply a turning force to the arrow wheel 21 in the clockwise direction. When the arrow wheel 21 rotates clockwise, the aperture diameter of the aperture blade 20 is greatly opened, and the arrow wheel 21 is resisted against the spring 36.
When is rotated counterclockwise, the diaphragm aperture is closed. Further, on the outer periphery of the arrow wheel 21, there is provided a locking piece 21d for restricting a rotation range of the arrow wheel 21 and a projecting piece having an inclined groove 21a.
21c is formed. A part of the arm 24 formed in an arc shape is fitted in the inclined groove 21a at a front end of a groove fitting pin 24b which is planted through the arm. The portion of the groove fitting pin 24b protruding rearward is the optical axis O.
It is fitted in an inclined groove 23a formed in a diaphragm plate 23 that is rotatably arranged around the center. The inclined groove 23a and the inclined groove 21a on the arrow wheel 21 have the same inclination angle and length shape. The slanted groove 23a of the diaphragm plate 23 is an arc groove 23 formed at a position equidistant from the optical axis O at one end close to the optical axis O of the groove.
It is continuous with b. Since the diaphragm plate rotating portion 12b of the diaphragm transmission member 12 is engaged with the notch 23c of the diaphragm plate 23, the connecting pin 24b of the arm 24 has the inclined groove 23a of the diaphragm plate 23 and the inclined groove 21a of the arrow wheel 21. When it is located near the center of
When the narrowing transmission member 12 is rotated counterclockwise against the spring 30, the slant surface of the slant groove 23a of the diaphragm plate 23 pushes the groove fitting pin 24b of the arm 24 so that the pin 24b is moved to the optical axis. It moves so as to approach O, and at this time, the arrow wheel 21 rotates counterclockwise to operate so that the diaphragm blade 20 closes.

A diaphragm cam plate 22 is rotatably fitted in the diaphragm frame 16. Two cam grooves 22a and 22b for determining the aperture diameter are continuously formed on the aperture cam plate 22.
The cam groove 22a is a releasing cam groove, and the cam groove 22b is a narrowing cam groove. A cam fitting pin 24a is also planted at the other end of the arm 24 so as to penetrate through the arm 24, and a portion of the pin 24a projecting forward is fitted in a long groove 16a formed by being inclined to the diaphragm frame 16. The portions of the pins 24a protruding rearward are fitted on the cam grooves 22a or 22b. The opening cam groove 22a is formed in an arc shape at a position away from the optical axis O, and the narrowing cam groove 22b is formed so as to be inclined so as to approach the optical axis O from one end continuous with the opening cam groove 22a. Has been done. Therefore, when the cam fitting pin 24a of the arm 24 is present on the open cam groove 22a, the groove fitting pin 24b of the arm 24 is located at the boundary between the inclined groove 23a of the diaphragm plate 23 and the arc groove 23b. Although it is located at the inflection point 23a ₀ , when the aperture cam plate 22 rotates counterclockwise, the cam fitting pin 24a comes to exist on the aperture cam groove 22b, Since the cam fitting pin 24a moves so as to approach the optical axis O, the groove fitting pin 24b comes to be positioned on the inclined groove 23a. As described above, the cam rotating portion 9b of the aperture value setting member 9 is engaged with the notch portion 22c of the aperture cam plate 22, so that the aperture cam plate 22 can be moved to a predetermined position by rotating the aperture ring 4. The rotation position corresponding to the F value is reached, and the narrowing cam groove 22
The cam fitting pin 24a is positioned on b.

Next, the operation of the zoom lens barrel configured as described above will be described. During zooming, when the zoom ring 6 is rotated, the cam ring 8 is rotated via the zoom pin 7, and the roller 18 is moved by the cam groove on the cam ring 8 and the rectilinear groove on the fixed frame 2. The frame 16 and the outer helicoid frame 25 provided on the pin 26 slide to move the first and second lens groups 41 and 42. Each lens group 41, 42, 43 of the zoom lens barrel
Is the zoom ring 6 from the telephoto side (T) through the standard (S) to the wide angle side.
When it is turned to (W), it moves as shown by the solid line in FIG. That is, the third lens group 43 is immovable, but the first and second lens groups 41 and 42 move by zooming, and in particular, the second lens group 42 provided with the automatic diaphragm mechanism 34 is It moves so as to be retracted backwards as the zooming from the telephoto side to the wide-angle side is performed. Since the first lens group 41 moves back and forth by the rotation of the distance ring 29, this lens group 41
41 moves from the dotted line to the solid line.

In the zoom lens barrel, when the correction function for keeping the open F value constant does not work, the open F value changes from F4.5 to F3.5, for example, as the zooming is performed from the telephoto side to the wide angle side. The following description will be given on the assumption that the lens barrel changes. The operation when the aperture ring 4 is rotated and the set aperture values are set to "F4.5", "F8", and "F3.5", respectively, will be described with reference to FIGS. 6 (A) to (C). First, as shown in FIG. 6 (A), "F
When the "4.5" aperture value scale is matched with the index 32, the interlocking plate 14 is in a state in which the connecting portion 9a of the aperture value setting member 9 is in contact with one end 14a ₀ of the cutout groove 14a (see FIG. 2). , Body interlocking part
14b is in contact with one end of the arc-shaped groove 13a of the cover frame 13, that is, the stopper portion 13a ₀ . That is, the body interlocking portion 14b is at a position inclined by a certain angle α from the reference position, and when in such a rotating position, the interlocking plate 14 informs the camera body side that the diaphragm is open.

When zooming to the telephoto side (T) at the aperture setting position of "F4.5", as shown in FIG. 3, the aperture cam plate 22 causes the inclined cam rotating portion of the aperture value setting member 9 to move. Since it is located at the tip of 9b, the aperture cam plate 22 rotates clockwise, and the cam fitting pin 24a of the arm 24 is located at the end of the opening cam groove 22a near the aperture cam groove 22b. Similarly, as shown in FIG. 4, since the diaphragm plate 23 is located at the tip of the inclined diaphragm plate rotating portion 12b of the diaphragm transmission member 12, the diaphragm plate 23 rotates clockwise and the arm 24 Groove mating pin 24b
Is located at the inflection point 23a ₀ of the inclined groove 23a. Therefore, in this state, since it does not move to the groove fitting pin 24b of the arm 24, the arrow wheel 21 does not rotate and the diaphragm blade 20 is not narrowed down, the diaphragm aperture is maximum and the open F value is "F4.5". Become. Then, in this state, even if the aperture transmission member 12 is rotated counterclockwise against the spring 30 by the operation of the aperture lever on the camera body side and the aperture plate 23 is rotated in the same direction, the groove fitting is performed. Since the dowel pin 24b is located on the circular arc groove 23b and does not move, the aperture blade 20 is not narrowed down.

Similarly, when the zoom is set to the wide-angle side (W) at the aperture setting position of "F4.5", the aperture cam plate 22 is moved to the position 22 'shown by the two-dot chain line in FIG. 3, that is, the aperture value. Since the cam rotation portion 9b of the transmission member 9 is located near the base end, the diaphragm cam plate 22 rotates counterclockwise, and the cam fitting pin 24a of the arm 24 moves to the position 22b '. Since the cam fitting pin 24a comes to exist on the groove 22b, the cam fitting pin 24a descends to a position near the optical axis O along the groove 16a on the diaphragm frame 16.
The position of the cam fitting pin 24a on the groove 16a at this time is a position corresponding to "F4.5" in the wide-angle state. Therefore, assuming that the diaphragm plate 23 does not rotate, the groove fitting pin 24b of the arm 24 corresponds to "F4.5" in the wide angle state in the direction away from the optical axis O along the inclined groove 23a. The diaphragm plate 23 is also moved to the position shown in FIG.
Since it is located at a position 23 'shown by a dotted line, that is, near the base end of the diaphragm plate rotating portion 12b of the diaphragm transmission member 12, this diaphragm plate 2
3 is rotated counterclockwise, and the groove fitting pin 24b of the arm 24 is in the state of existing at the position of the inflection point 23a ₀ after the movement. At this time, is the vane wheel 21 is the angle rotated counterclockwise by position to rotate counterclockwise inflection point 23a ₀ after movement of Mizohamago pin 24b is diaphragm plate 23, the As a result, the diaphragm blade 20 is narrowed down to a diaphragm aperture corresponding to an open F value of "F4.5" in this wide-angle state. In this state, when the narrowing transmission member 12 is rotated counterclockwise from the camera body side, in this case also, the groove fitting pin 24b exists on the inflection point 23a ₀ of the inclined groove 23a. , Open F value "F4.
No more narrowed down than 5 ", so" F4.5 "
Shooting will be performed at the open value of.

Even if you zoom to any position between the telephoto side (T) and the wide-angle side (W), the same operation as when zooming to the wide-angle side is performed, and "F4.5" is set according to the focal length at that position. The diaphragm blades 20 are narrowed down to a diaphragm aperture having an open F value. Therefore, if the position of the aperture ring 4 is set to the aperture value of "F4.5", the open F number does not change due to zooming and becomes constant at "F4.5".

Next, as shown in FIG. 6 (B), “F8” on the aperture ring 4
If the aperture value scale of is matched with the index 32,
Is a connecting portion 9a of the aperture value setting member 9 at one end 14a ₀ of the cutout groove 14a.
State but in contact with (see Fig. 2), the body interlocking portion 14b from the stopper portion 13a ₀ arcuate groove 13a of the cover frame 13,
They are separated in the counterclockwise direction by an angle corresponding to the light amount difference between "F4.5" and "F8". That is, the body interlocking portion 14b is at a position inclined by a certain angle β (> α) from the reference position, and when in such a pivoting position, the interlocking plate 14 moves from the aperture open to the camera body side to the above light amount step. Tell them that the number of stops will be reduced.

When zooming to the telephoto side (T) at the aperture setting position of "F8", the aperture cam plate 22 is located at the tip of the cam rotating portion 9b of the aperture value setting member 9, but the " When the aperture cam plate 22 is rotated counterclockwise by the cam rotating portion 9b by the rotation of "F8", the cam fitting pin of the arm 24 is rotated.
24a is the narrowing cam groove 22b and the long groove 16a of the diaphragm frame 16.
Above, the arm 24 moves to a position corresponding to "F8" in the telephoto state, so that the arm 24 rotates counterclockwise along the inclination of the long groove 16a. Therefore, at this time, the groove fitting pin 24b is
Since 3 does not rotate, it rises away from the optical axis O along the inclined grooves 23a and 21a. Therefore, the arrow wheel 21 does not rotate, the diaphragm blade 20 is not narrowed down, the diaphragm aperture is maximum, and the open F value remains "F4.5". In this state, when the diaphragm transmission member 12 is rotated counterclockwise from the camera body side, the diaphragm plate 23 also rotates in the same direction, and at this time, the groove fitting pin 24b is formed on the inclined surface of the inclined groove 23b. It is pushed down in the direction of the optical axis O, so that the arrow wheel 21 rotates counterclockwise and the diaphragm blades 20 are narrowed down to the diaphragm aperture of "F8".

Similarly, at the aperture setting position of "F8" above, at the wide angle side
When (W) zooming is performed, the diaphragm cam plate 22 is located closer to the base end of the cam rotating portion 9b of the aperture value transmitting member 9, and therefore further rotates counterclockwise to move the cam on the arm 24. The fitting pin 24a is located on the narrowing cam groove 22b at a position corresponding to "F8" in the wide-angle state. Then, the groove mating pin 24
Assuming that the diaphragm plate 23 does not rotate, b moves up the inclined groove 23a to a position corresponding to "F8" on the wide angle side. Since it rotates by the same angle as the rotation angle in the wide-angle state, the arrow wheel 21 also rotates by the same angle, and the diaphragm blade 20 is "F4.5" in the wide-angle state.
Is narrowed down to the aperture size of. Further, in this state, when the aperture transmission member 12 is rotated counterclockwise, the aperture plate 23
Rotates further to push down the groove fitting pin 24b on the inclined surface of the inclined groove 23a, so that by rotating the arrow wheel 21 at this time, the diaphragm blade 20 is narrowed down to a wide-angle "F8" diaphragm aperture.

In addition to the above "F4.5" and "F8", "F4.5"
Even when the aperture value is set to a larger aperture value "F5.6" or "F11", the open F-number is "F4" regardless of zooming as in the case of the aperture values "F4.5" and "F8". .
The aperture diameter is corrected so that it becomes 5 ”, and open metering with this constant F value is possible.

Next, as shown in FIG. 6 (C), "F3.5" on the diaphragm ring 4
When the aperture value scale of is matched with the index 32, the aperture value setting member 9 is moved to the position corresponding to "F3.5" further rotated clockwise beyond the position corresponding to "F4.5". since throughout the body interlocking portion 14b of the interlock plate 14 abuts against the stopper portion 13a ₀ arcuate groove 13a of the cover frame 13, the aperture value setting member 9
The connecting portion 9a of the interlocking plate 9a is notched in the interlocking plate 14 against the tensile force of the spring 31.
It is separated from the one end 14a _{0 of} 14. Therefore, even when the aperture ring 4 is set to the "F3.5" position, the body interlocking portion 14b of the interlocking plate 14 is tilted from the reference position by the rotation angle α as in the case of "F4.5". Therefore, the camera stays in the open position to notify the camera body that the aperture has been opened.

When zooming to the telephoto side (T) at the aperture setting position of "F3.5", the aperture cam plate 22 is located at the tip of the cam rotating portion 9b of the aperture value transmission member 9, so that the telephoto state is set. Rotate clockwise beyond the position corresponding to "F4.5" in. Therefore, the cam fitting pin 24a of the arm 24 moves up to the position of the opening cam groove 22a on the diaphragm cam plate 22. Then, the groove fitting pin 24b of the arm 24 is set to "F" in the telephoto state.
As in the case of "4.5", the inflection point 23 of the inclined groove 23a of the diaphragm plate 23
Since the diaphragm plate 23 is located at a ₀ and the diaphragm plate 23 does not rotate, the arrow wheel 21 does not rotate at this time, the diaphragm blade 20 is not narrowed down, and the open F value becomes "F4.5". Further, in this state, even if the aperture transmission member 12 is rotated counterclockwise from the camera body side and the aperture plate 23 is also rotated in the same direction, at this time, the groove fitting pin 24b is placed on the arc groove 23b. There is no escape or movement, so no narrowing is done.

After that, when zooming to the wide-angle side (W) is also performed at the aperture setting position of "F3.5", the aperture cam plate 22 causes the cam rotation portion of the aperture value setting member 9 to operate as in the case described above. 9
Since it is located closer to the base end of b, it rotates counterclockwise than in the telephoto state, so that the cam fitting pin 24a of the arm 24 is closer to the opening cam groove 22a than the narrowing cam groove 22b. End, that is, the same position as in the case of "F4.5" in the telephoto state. Therefore, if the groove fitting pins 24b are diaphragm plate 23 of the arm 24 is not rotated, but located in the inflection point 23a ₀ of the inclined groove 23a, this time, the diaphragm plate 23 also stop narrowing transmitting member 12 The diaphragm plate 23 reaches the position near the base end of the plate rotating portion 12b, so that the diaphragm plate 23 rotates counterclockwise due to the inclination of the diaphragm plate rotating portion 12b. Therefore, the groove fitting pin 24b is
Since it is located on the circular arc groove 23b and is not moved by the diaphragm plate 23, the arrow wheel 21 remains stationary and the diaphragm blades 20 are not narrowed down. Therefore, the aperture diameter is open, and the open F value "F4.5" in the telephoto state is maintained, that is, the open F value "F3.5" is obtained in this wide angle state. Further, in this state, even if the narrowing transmission member 12 is rotated in the counterclockwise direction from the camera body side, the groove fitting pin 24b can move on the circular arc groove 23b of the rotating diaphragm plate 23. Therefore, the aperture blade 20 is not narrowed down, and the open F value “F3.5” is maintained.

Further, even when the zoom setting position of "F3.5" is zoomed to any position between the telephoto side (T) and the wide angle side (W), the cam fitting pin 24a of the arm 24 does not move the diaphragm cam plate. Since it is located on the opening cam groove 22a of 22, the groove fitting pin 24b is located on the circular arc groove 23b of the diaphragm plate 23, so that the diaphragm blades 20 are not narrowed down, and therefore the diaphragm aperture is maximum. Yes, the open F value is "F4.5" to "F3.
The value changes according to the focal length at the position between the telephoto side (T) and the wide-angle side (W). Also, the body interlocking part of the interlocking plate 14
Since 14b is in the open position by coming into contact with the stopper portion 13a ₀ of the arcuate groove 13a of the cover frame 13, the camera body side can detect this and perform open metering at the maximum aperture diameter.

Next, another embodiment of the present invention will be described.

FIG. 7 is an exploded perspective view of a main part of a zoom lens barrel according to another embodiment of the present invention. It is assumed that each part of the zoom lens barrel other than the part shown in FIG. 7 has substantially the same structure as the zoom lens barrel shown in FIG. The unit of the automatic diaphragm mechanism 64 is disposed in the diaphragm frame 16, and the plurality of diaphragm blades 50 are held between the blade retainer 19 (see FIG. 1) and the arrow wheel 51, like the automatic diaphragm mechanism 34. The support holes 50b on each diaphragm blade 50 are connected to the pins 16b on the diaphragm frame 16.
The engaging pin 50a is engaged with the notch 51b on the inner peripheral side of the arrow wheel 51. Between the arrow wheel 51 and the diaphragm frame 16, a spring for constantly applying a turning force to the arrow wheel 21 in the counterclockwise direction.
When the arrow wheel 51 is rotated counterclockwise by the force of the spring 52, the diaphragm blades 50 are closed, and the arrow wheel 51 rotates clockwise against the force of the spring 52. When it moves, the diaphragm blade 50 operates so that the diaphragm aperture is opened. Further, on the outer periphery of the arrow wheel 51, an engaging claw 51a that engages with the narrowing transmission member 58 and a pin 53a on the bell crank lever 53 are provided.
A stop claw 51b that engages with is formed. A ring-shaped aperture cam plate 54 is rotatably fitted to the aperture frame 16 at the rear of the arrow wheel 51. A part of the aperture cam plate 54 has an outer periphery equidistant from the optical axis O. Circular arc-shaped opening cam surface 54a
Then, a narrowing cam surface 54b having a shape gradually approaching the optical axis O from one end of the cam surface 54a is continuously formed. Further, a protrusion 54c for driving the aperture cam plate 54 is formed on the outer periphery of the aperture cam plate 54. The bell crank lever 53 is rotatably supported on the diaphragm frame 16 by a support shaft 53c, and the pin 53a extending forward determines the stop position of the arrow wheel 51 for narrowing down and is counterclockwise from the stop claw 51b. The cam engagement pin 53b, which extends toward the outer peripheral position of the arrow wheel 51 and extends rearward, is formed on the cam surface 54a of the aperture cam plate 54.
Or it is abutting on 54b.

A diaphragm value setting member 55 is fixed to the diaphragm ring connecting member 56, and the setting member 55 gives the habit of rotating counterclockwise by a spring 57 stretched between the diaphragm ring setting member 55 and a stationary member in the lens barrel. However, the diaphragm ring connecting member 56 is stopped by the spring 57 abutting against the locking portion of the diaphragm ring (not shown).
Therefore, when the diaphragm ring is rotated, the diaphragm ring connecting member 56 is rotated while being in contact with the diaphragm ring. The stop ring is provided with a click stop mechanism between the stop ring and the fixed frame. The arm portion 55a extending forward along the optical axis O of the aperture value setting member 55 is formed with a cam rotation long groove 55b inclined slightly clockwise from the rear to the front, and the aperture cam plate is formed in the same long groove 55b. The protruding portion 54c on the upper portion 54 is fitted. A brilliance side pin 60a at one end of the aperture value transmission link 60 is rotatably fitted in a support hole of a link holding portion 55c formed at the rear of the aperture value setting member 55. Movement side pin 60b at the other end of the link 60
Is slidably fitted in an inclined groove 61a formed in a ring-shaped interlocking plate 61 arranged so as to be rotatable around the optical axis O. On the outer periphery of the interlocking plate 61, a body interlocking part 61b that engages with an interlocking member such as an exposure meter on the camera body side is provided in the third lens group 4.
It is provided so as to project rearward from the arc-shaped groove 62a on the cover frame 62 to which 3 is fixed, and this body interlocking part 61b has a diaphragm ring with a predetermined aperture value on the open aperture side, that is, a telephoto of the lens system. When set to the scale of aperture values (“F4.5” and “F3.5” in the above embodiment) corresponding to the open F value at the time of opening and the open F value at the time of wide angle, the stopper portion at one end of the groove 62a. 62a ₀
It is designed to come into contact with. In addition, the interlocking side pin
The end portion extending further rearward of 60b has an arc-shaped cam surface 63a of the link cam 63 fixed to the cover frame 62, or an inclination angle corresponding to the inclination of the inclined groove 61a from one end of the cam surface 63a. Is in contact with the cam surface 63b rising in the direction away from the optical axis O.

The narrowing transmission member 58 is rotatably arranged around the optical axis O, and is normally urged to rotate clockwise by a spring 59 stretched between it and a stationary member. On the left side surface of the arm portion 58c extending to the front of the narrowing transmission member 58, a cam surface 58a inclined clockwise from the rear to the front is formed, and the cam surface 58a abuts on the engaging claw of the arrow wheel 51. There is. Since the turning force of the narrowing transmission member 58 by the spring 59 is stronger than the turning force of the arrow wheel 51 by the spring 52, the arrow wheel 51 is normally rotated clockwise against the spring 52 to move the diaphragm blade 50. It is designed to be held in the fully open position. Therefore, the automatic diaphragm mechanism 64 is a non-compulsory type.
An engagement portion 58b that engages with an aperture drive lever (not shown) on the camera body side is formed behind the aperture transmission member 58. When the body interlocking part 61b of the interlocking plate 61 is turned clockwise while the aperture ring is rotated counterclockwise and set to the minimum aperture value, the aperture value setting member 55 rotates against the spring 57. It is possible to move and set the aperture value arbitrarily.

Next, the diaphragm control operation in the zoom lens barrel of the above embodiment will be described. The zoom lens barrel in this embodiment has the same lens system as the lens system of the zoom lens barrel in the previous embodiment, namely, "F4.5" on the telephoto side (T) and "F3. It is assumed that a lens system having an open F value of 5 "is used.

First, set the aperture ring to the "F4.5" position, and link 6
The interlocking side pin 60b of 0 is interlocking plate 61 as shown in FIG. 8 (A).
Is set at a position where the inclined groove 61a and the cam surface 63b of the link cam 63 coincide with each other, and is located at the boundary point between the cam surface 63a and the cam surface 63b of the link cam 63. At this time, the interlocking plate 61
The rotational position of is the open position where the body interlocking portion 61b abuts the stopper portion 62a ₀ . Then, when the zoom ring is operated to zoom to the telephoto side at the aperture setting position of "F4.5", the automatic aperture mechanism 64 moves forward along the optical axis O together with the aperture frame, so the arrow wheel 51 narrows down. Arm 58 of transmission member 58
Located at the front end of c, the aperture cam plate 54 is located at the front end of the arm 55a of the aperture value setting member 55. The sash 51 has a cam surface 58 on the arm 58c.
Since it is located at the front end of a, it is regulated in the most clockwise rotation state, and the aperture blade 50 is fully opened and the open F value is "F4.5". Further, at this time, the stop position of the diaphragm cam plate 54 is determined by the engagement of the long groove 55b and the protrusion 54c at the front end of the arm 55a, and the stop position of the diaphragm cam plate 54 at this rotating position is The pin 53b of the bell crank lever 53 is located at an inflection point 54a ₀ between the opening cam surface 54a and the narrowing cam surface 54b. As a result, the position of the pin 53a of the bell crank lever 53 is also the position on the outer periphery of the arrow wheel 51 that has moved to the most clockwise direction. Therefore, in this state,
Even if the narrowing transmission member 58 rotates counterclockwise against the spring 59 due to release, the arrow wheel 51 is not rotated by being restricted by the pin 53a. It keeps "F4.5".

If the zoom ring is zoomed to the wide-angle side while the position of the aperture ring is set to "F4.5", the arrow wheel 51 and the aperture cam plate 54 move rearward, so that the arrow wheel 51 is rotated counterclockwise by the cam surface 58a. The diaphragm cam plate 54 rotates counterclockwise by the long groove 55b. Therefore, the rotation of the arrow wheel 51 causes the diaphragm blade 50 to rotate.
Is narrowed down to a diaphragm aperture equivalent to "F4.5" in the wide-angle state. Further, due to the rotation of the diaphragm cam plate 54, the pin 53b of the bell crank lever 53 stands still on the diaphragm cam surface 54b at a position corresponding to "F4.5" in the wide-angle state. Therefore, the pin 53a moves to the left of the position of the pin 53a in "F4.5" in the telephoto state.
The stop claw 51b of the arrow wheel 51 rotated counterclockwise by the zooming comes into contact with the pin 53a. Therefore, in this state, even if the squeezing transmission member 58 rotates counterclockwise due to the release, the arrow wheel 51 does not rotate any further, and the squeezing aperture holds "F4.5" in the wide-angle state. .

Next, when the aperture ring is rotated counterclockwise further toward the aperture side than “F4.5” and set to the position of “F5.6”, for example, the interlocking side pin 60b of the link 60 is shown in FIG. As shown in B), it abuts on the arcuate cam surface 63a of the link cam 63. Therefore, the rotation position of the interlocking plate 61 is determined by the interlocking side pin 60b located at one end of the inclined groove 61a near the optical axis O. That is, the interlocking plate 61 rotates counterclockwise by the rotation amount l ₁ from the position of "F4.5" to the position corresponding to "F5.6".
As a result, the body interlocking portion 61b is separated from the stopper portion 62a ₀ by the above-described rotation amount l _{1, and the} number of diaphragm steps corresponding to the light amount step difference of “F4.5” to “F5.6” from the aperture open to the camera body side. Information is transmitted.

When zooming toward the telephoto side at the aperture setting position of "F5.6", the arrow wheel 51 engages with the front end portion of the cam surface 58a as in the case of the telephoto state at "F4.5". Although the diaphragm blades 50 are in the position and the diaphragm blades 50 are fully opened, the diaphragm cam plate 54 is rotated counterclockwise as compared with the case of "F4.5". Therefore, since the pin 53b is located on the narrowing cam surface 54b, the bell crank lever 53 rotates clockwise, the pin 53a moves leftward and separates from the stop pawl 51b,
It reaches the position equivalent to "F5.6" in the telephoto state. Therefore, before the shutter release, the open aperture is "F4.5", but when the aperture stop transmission member 58 rotates counterclockwise due to the release, the arrow wheel 51 rotates the stop pawl 51b at the pin 53a. When it reaches the moving position, the diaphragm blade 50 is narrowed down to "F5.6".

When zooming to the wide-angle side at the above-mentioned "F5.6" aperture setting position, the arrow wheel 51 performs the same rotation as in the "F4.5" wide-angle state, and the aperture blades
50 is narrowed down to the aperture of "F4.5" in the wide-angle state. Further, since the aperture cam plate 54 rotates corresponding to "F5.6" in the wide-angle state, the pin of the bell crank lever 53
53b is "F5.
Stationary at a position equivalent to 6 ". Therefore, the pin 53a comes to a position corresponding to "F5.6" in the wide-angle state, which is moved leftward from the position "F5.6" in the telephoto state. Therefore, before the shutter release, "F
Although the aperture diameter of 4.5 "is obtained, when the release transmission is performed and the aperture transmission member 58 is rotated, the arrow wheel 51 is moved to the pin 53.
When the rotation position is restricted to a, the diaphragm blade 50 is narrowed down to the diaphragm aperture of "F5.6" in the wide-angle state.

Next, set the aperture ring to the "F3.5" position, and link 6
The interlocking side pin 60b of 0 rotates the interlocking plate 61 clockwise,
The body interlocking part 61b is the stopper part 62 at the turning position of "F4.5".
After abutting on a ₀ , it receives the force to move further clockwise. Therefore, the link 60 receives a turning force in the counterclockwise direction around the preset side pin 60a, and the interlocking side pin 60b rises along the inclined groove 61a and the inclined cam surface 63b. That is, the position of the preset side pin 60b of the link 60 is the same as the "F
Rotation amount l from the position of "4.5" to the position corresponding to "F3.5"
_Although it rotates clockwise by _2, the position of the interlocking plate 61 is the same as in the case of "F4.5".
It will be in the open position where it abuts 62a ₀ .

When zooming to the telephoto side at the aperture setting position of "F3.5", in this telephoto state, the arrow wheel 51 causes "F4.
As in the case of the telephoto state in "5", the aperture blade 50 is fully opened by rotating clockwise and the open F value is "F".
It is 4.5 ”. The aperture cam plate 54 is also the aperture value setting member 55.
The pin 53b of the bell crank lever 53 is located in the vicinity of the end on the side far from the inflection point 54a ₀ on the opening cam surface 54a, since it has been completely rotated clockwise by. Therefore, the pin 53a of the bell crank lever 53 is in the most fully clockwise position on the outer periphery of the arrow wheel 51, and is in contact with the stop claw 51b, like the position of the "F4.5" in the telephoto state. Therefore, in this state, even if the shutter is released and the diaphragm transmission member 58 rotates counterclockwise, the arrow wheel 51 does not rotate, and the diaphragm blades 50 are fully open. In this telephoto state, "F4. It has an open F value of 5 ".

Further, when the wide-angle side is zoomed while the position of the diaphragm ring is set to "F3.5", in this case, the arrow wheel 51 moving rearward by zooming causes the stop claw 51b and the pin 53b to engage with each other. If not taken into consideration, the engaging claw 51a and the cam surface 58
Due to the engagement relationship with a, it will stop at the same rotational position as in the wide-angle state in "F4.5". But,
Zooming causes the diaphragm cam plate 54 to move backward and
When the pin 53b of the bell crank lever 53 is rotated in the counterclockwise direction due to the engagement relationship between the 55b and the protrusion 54c, the pin 53b of the bell crank lever 53 is released.
It slides up and reaches the position of inflection point 54a ₀ and stands still. Therefore, the position of the bell crank lever 53a does not move due to this zooming, and is the most clockwise position on the outer periphery of the arrow wheel 51, like the position in the telephoto state of "F4.5". Even when zooming to the wide-angle side, the engagement position between the stop claw 51b and the pin 53a does not change, and
Stops at the rotating position where the diaphragm blade 50 is fully opened. Therefore, at this time, the open F value is "F3.5". Further, in this state, even if the shutter release is performed and the diaphragm transmission member 58 rotates counterclockwise, the arrow wheel 51 does not rotate, so the diaphragm blade 50 remains fully open.

When the aperture ring is set to "F3.5" in this way, the aperture blade 50 is fully opened in the entire zoom range from the telephoto side to the wide-angle side, and the aperture is maximized. .Five"
With the so changed continuously until "F3.5" in the wide-angle state, the body interlocking portion 61b of the interlock plate 61 keeps the state that existed in contact with the open position to the stop portion 62a _0.

FIG. 9 shows a modification of the diaphragm cam plate for driving the bell crank lever 53 in FIG. 7 and the diaphragm value transmitting member for driving the diaphragm cam plate. In this modification, the ring-shaped diaphragm cam plate 74 is urged in the clockwise direction by a spring 72 stretched between the locking claw 74d and the immovable member, and the optical axis O implanted in the immovable member. The locking claw 74d abuts the long locking pin 71 in parallel with and the rotation is stopped. Further, on the outer periphery of the aperture cam plate 74, a protrusion 74c that engages with the front end of the arm portion 75a of the aperture value transmission member 75 is provided, and further, on the other portion of the outer periphery,
An opening cam surface 74a is formed at a position at a constant distance from the optical axis O in an extremely narrow range, and a constriction cam surface 74b is formed on the clockwise side continuously from the opening cam surface 74a. The aperture value transmission member 75 fixed to the aperture ring is a cam surface 75b in which the counterclockwise side surface of the arm portion 75a is inclined, and a link holding portion 75c is formed at the rear end.

In the zoom lens barrel having the aperture cam plate 74 and the aperture value transmission member 75, first, when the aperture ring is set to "F4.5" and then in the telephoto state, Figs.
As shown in (A), the tip of the cam surface 75b of the aperture value transmission member 75 contacts the protrusion 74c of the aperture cam plate 74, and the locking claw 74d of the aperture cam plate 74 also contacts the locking pin 71. . Therefore,
At this time, the diaphragm cam plate 74 is in the most fully rotated clockwise state and stopped rotating, and the pin 53b of the bell crank lever 53 is located on the opening cam surface 74a. Therefore, the pin 53a rotates counterclockwise around the support shaft 53c of the bell crank lever 53 and is located at the rightmost position, and the diaphragm blade 50 (see FIG. 7) is fully opened. After that, when zooming is performed in the direction of the wide angle side, the aperture cam plate 74 is restricted by the cam surface 75b of the aperture value transmission member 75, so the spring 7
It moves backward while turning counterclockwise against the turning force of 2. For this reason, the position of the narrowing cam surface 74b also moves counterclockwise, so that the pin 53b of the bell crank lever 53 moves from above the opening cam surface 74a to the narrowing cam surface 75b.
b Moves up and descends gradually. Therefore, by zooming from the telephoto side to the wide-angle side, the pin of the crank lever 53
53a moves to the left, whereby the diaphragm blade 50 is gradually narrowed down and the open F value of "F4.5" is maintained.

Further, when the aperture ring is rotated clockwise from the above "F4.5" position to align with the "F3.5" position, the aperture value transmission member 75 will stop the aperture value as shown in FIG. 10 (B). Even if the diaphragm cam plate 74 moves rearward by moving together with the ring and separating from the protruding portion 74c of the diaphragm cam plate 74, the cam surface 75
It reaches a position where b and the protruding portion 74c are not in contact with each other. Therefore,
The pin 53b of the bell crank lever 53 remains positioned on the opening cam surface 74a of the aperture cam plate 74, so that the aperture aperture remains unchanged at the maximum even when zooming is performed.
The open F value changes from "F4.5" in the telephoto state to "F3.5" in the wide-angle state.

(Effect) As described above, according to the present invention, when the aperture ring is set to an aperture value equal to or larger than the aperture F value at the time of telephoto, it has a function of keeping the aperture F value constant regardless of zooming. At the same time, when the aperture ring is set to an aperture value smaller than the aperture F value at the time of telephoto, the function of keeping the aperture F value constant can be canceled to make the aperture F value brighter than the constant aperture F value. Since this is possible, it is effective in combination with a camera having an AE lock function, and is also convenient for focusing on a dark subject. Also, transmission for transmitting the aperture value to the camera body side when the aperture ring is set to the aperture value corresponding to the open F value at telephoto and when set to the aperture value corresponding to the wide open angle F value. Since the members are in the same open state, an excellent effect such as open metering is possible during this period.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a zoom lens barrel showing an embodiment of the present invention, and FIG. 2 is an enlarged perspective view showing an exploded main part of the zoom lens barrel shown in FIG. FIG. 3 is a diagram for explaining the positional relationship between the aperture value setting member and the aperture cam plate that changes due to zooming, and FIG. 4 is a diagram for explaining the positional relationship between the aperture transmission member and the aperture plate that changes due to zooming. , FIG. 5 is a diagram showing a change in the position of each lens unit due to zooming and a change in the open F value when no correction is performed, and FIGS. 6 (A) to 6 (C) show each aperture value of the aperture ring. FIG. 7 is an explanatory view showing the position of the interlocking plate with respect to the setting and the diaphragm operation and diaphragm aperture during zooming, respectively. FIG. 7 is a perspective view of the diaphragm control mechanism in the zoom lens barrel showing another embodiment of the present invention. Figures (A) to (C) show the camera book for each aperture value setting on the aperture ring. FIG. 9 is a perspective view showing a partial modification of the aperture control mechanism shown in FIG. 7, showing the position of the interlocking member for transmitting the aperture value to the body side. 9A and 9B are front views for explaining the operation of the aperture control mechanism shown in FIG. 9 when different open F values are set. 4 ...... Throttle ring 9a ...... Coupling part (separation means) 12,58 ...... Throttle transmission member (automatic squeezing member) 14,61 ...... Interlocking plate (aperture value transmission member) 14a ...... Notched groove (separation means) 20 , 50 ... Aperture blade 21, 51 ... Arrow wheel (Aperture blade operating member) 22, 54, 74 ... Aperture cam plate (Aperture aperture determination member) 23 ... Aperture plate (Aperture correction mechanism) 24 ... Arm (〃 ) 31 …… Interlocking spring (disengagement means) 36,72 …… Spring (released state holding means) 51a …… Engagement claw (〃) 53 …… Bell crank lever (iris correction mechanism) 60 …… Link (released state maintenance) Means) 61a …… Inclined groove (open state holding means) 63a, 63b …… Cam surface (open state holding means)

Claims (1)

[Claims] 1. An aperture ring for determining an aperture value at the time of shooting, and an aperture value transmission that moves in conjunction with the aperture ring to transmit the aperture value set by the aperture ring to a photometric circuit on the camera side. A member, an aperture aperture determination member that moves in conjunction with the aperture ring and has an aperture cam portion for controlling the aperture aperture by the aperture blades to the set aperture value of the aperture ring, and a series of shootings when the release button is pressed. An aperture blade operating member that operates in conjunction with an automatic aperture member that is driven from the camera side in the initial stage of operation to perform aperture operation of the aperture blades, and the aperture ring, the aperture diameter determination member, and the automatic aperture member that interlock with zooming operation. And an aperture correction mechanism that changes the relative position of the aperture blade operating member to obtain an aperture diameter according to the aperture value set for the aperture ring over the entire zoom range, and the aperture ring and the aperture value transmission member. When the set aperture value of the aperture ring is set between the telephoto side aperture value by the maximum aperture diameter and the wide-angle side aperture value, the interlock between the aperture ring and the aperture value transmission member is cut off. A zoom lens barrel comprising: a means for holding the aperture blades in an open state, which is provided in the aperture diameter determining member.