JPH082646Y2 - 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 that extends a rotating barrel that is helicoidally coupled to a fixed barrel in the optical axis direction.

"Prior art and its problems" In a zoom lens barrel in which a rotary cylinder having a male helicoid is screwed into a fixed cylinder having a female helicoid and which is extended in the optical axis direction while rotating the rotary cylinder,
For example, in order to provide a drive mechanism for rotating the rotary cylinder,
A notch for disposing the drive mechanism may be formed in the female helicoid on the fixed cylinder side. Since the notch partially divides the female helicoid, the threaded engagement of the male helicoid of the rotary cylinder with the female helicoid is partially released at the specific rotational position of the rotary cylinder at the notched portion.

By the way, the male and female helicoids have clearance in the width direction. Therefore, in the cutout portion, when the male helicoid that has once disengaged from the female helicoid tries to re-engage with the female helicoid by reversing the rotation direction, this clearance causes the end surface of the male helicoid to move into the cutout portion. There is a possibility of interfering with the end surface of the facing female helicoid, and in the worst case, this stops the progress of the helicoid and hinders the rotation of the rotary cylinder.
Especially when forming male and female helicoids with resin material,
This clearance tends to be large due to the need to address formability and screwing incompatibility due to temperature changes, making this problem a close-up.

[Object of the Invention] The present invention is that a fixed cylinder having a male helicoid is screwed with a rotary cylinder having a female helicoid, and a screw engagement of a male helicoid with a female helicoid is fixed to a fixed cylinder at a specific rotation position. In the zoom lens barrel of the type that is partially released by, the interference in the end face direction of the helicoid when the once released meshing occurs again due to the reversal of the rotation direction is eliminated, and the movement of the rotation barrel in the optical axis direction relative to the fixed barrel is eliminated. The objective is to obtain a zoom lens barrel that can be smoothly operated.

[Outline of the Invention] The present invention that achieves the above object is provided with a pair of tubular bodies connected by screwing helicoids, and at least one tubular body has a cutout portion in which a part of the helicoid mountain is removed. Having the notch, in the zoom lens barrel through which the helicoid mountain of the other tubular body or the end of the helicoid mountain passes, at the end of each helicoid mountain forming the notch, the interval between adjacent helicoid mountains is It is characterized by forming an inclined surface that gradually expands toward the notch.

INDUSTRIAL APPLICABILITY The zoom lens barrel of the present invention can be used for a lens shutter type camera in which a fixed barrel is fixed to a camera body, and an interchangeable lens type camera which can be attached to and detached from the camera body.

"Embodiment of the Invention" The present invention will be described below with reference to illustrated embodiments. In the illustrated embodiment, the zoom lens barrel of the present invention is applied to a lens shutter type camera having a macro photographing function, and FIGS. 4 to 6 show a retracted position, a wide end position and a tele end position, respectively. There is.

A fixed barrel 12 is fixed to a camera body 11 of the lens shutter type camera. 13 and 14 are an outer rail and an inner rail formed as a film guide on the camera body.
According to this embodiment, the movable lenses 15 and 16 of the front and rear two groups can be retracted and housed to a state where they are extremely close to the outer rail 13 and the inner rail 14, and the annular members such as the cam ring are also short and the housing length is short.

A female helicoid (outer helicoid) 18 is fixed to the fixed barrel 12 via a fixing screw 19.
A cam ring 22 having a male helicoid (inner helicoid) 20 is screwed into the 18. Female helicoid 18 and male helicoid
20 is made of, for example, a resin material, and a predetermined clearance c shown in an exaggerated manner in FIG. 3 is set between the two. Female helicoid 18 and male helicoid
20 constitutes a pair of tubular bodies that are helicoid-bonded.

The female helicoid 18 is provided with a notch 45 at a part thereof for disposing a drive mechanism (not shown) for rotationally driving the cam ring 22, for example. Therefore, when the cam ring 22 rotates and the end surface of the male helicoid 20 enters the notch 45, a part of the male helicoid 20 releases the screw engagement with the one end surface 45a of the notch 45.

The present invention uses the end face 46 of the female helicoid 18 facing the notch 45.
It is characterized by the shape of. That is, the end surface 46 is provided with an inclined surface 46a that gradually opens the groove width of the helicoid groove 18b between the adjacent helicoid peaks 18a toward the notch 45.
This inclined surface 46a, the end surface of the male helicoid 20 that has been disengaged with the female helicoid 18 in the notch 45, when trying to mesh again with this female helicoid 18 by reversing the rotation direction, the female helicoid 18 and the male helicoid 20 It avoids collision between the end faces that may occur due to the clearance c set between them, and functions to guide the end face of the helicoid mountain 20a of the male helicoid 20 to the helicoid groove 18b of the female helicoid 18 to be meshed. Also, on the end face of the helicoid mountain 18a,
In order to avoid collision between the radial end faces of the female helicoid 18 and the male helicoid 20, the height of the helicoid peak 18a is cut out 45.
An inclined surface 46b is formed so as to be lowered toward. In addition,
A similar inclined surface 20b can be attached to the end surface of the male helicoid 20.

A cam ring 22 is fixed to the male helicoid 20 via a fixing screw 21 (see FIG. 7). For male helicoid 20,
As shown in FIG. 7, a gear 20c that is inclined at the same angle as the inclination of the helicoid crest 20a is formed.
The cam ring 22 is rotationally driven in the forward and reverse directions through a pinion that meshes with and a motor (both not shown) that rotationally drives the pinion. Therefore, when the cam ring 22 is rotationally driven, it moves in the optical axis direction according to the lead of the helicoid crest 20a.

A lens guide ring 24 is fitted on the inner circumference of the cam ring 22. A straight guide plate 26 is fixed to the rear end of the lens guide ring 24 with a fixing screw 25.
Has a part of its outer periphery engaged with a lens guide ring guide groove 27 formed on the inner surface of the fixed barrel 12. The lens guide ring guide groove 27 is a linear groove in the optical axis direction in this embodiment. An inner flange 29 formed at the rear end of the cam ring 22 is relatively rotatably fitted in an annular groove 28 formed between the linear guide plate 26 and the rear end of the lens guide ring 24. Therefore, although the lens guide ring 24 is restricted from rotating by the lens guide ring guide groove 27, the lens guide ring 24 always moves integrally with the cam ring 22 in the optical axis direction, and the cam ring 22 moves relative to the lens guide ring 24. Can rotate.

The front and rear two groups of movable lenses 15 and 16 are fixed to a front group lens frame 30 and a rear group lens frame 31, respectively, which are located inside the lens guide ring 24. The front lens group frame 30 is a shutter block
The helicoid ring 33 fixed to 32 is helicoid-bonded. The shutter block 32 is fixed to the front group moving frame 34, and at least three guide pins 35 are provided on the outer peripheral portion of the front group moving frame 34. Similarly, at least three guide pins 36 are provided on the outer periphery of the rear lens group frame 31. Note that the guide pins 35 and 36 are overlapped in FIGS. 1 and 3 for convenience of illustration.

As is well known, the shutter block 32 rotates the drive pin 32a by an angle corresponding to the distance signal from the distance measuring device to the object, and the front group lens frame 3 connected to the drive pin 32a.
Rotate 0 together to move along the helicoid along the optical axis to adjust the focus. Further, the shutter blade 32b is operated according to the brightness signal of the subject.

38 is a lens cover cylinder provided integrally with the front group moving frame 34, 39
Is a decorative cylinder that covers the outer circumferences of the lens guide ring 24 and the cam ring 22 protruding from the main body shell 11a.

The cam ring 22 is provided with a front group cam groove 41 and a rear group cam groove 42 through which the guide pins 35 and 36 are inserted, and a lens guide groove 24 is formed in each of the front group cam groove 41 and the rear group cam groove. Lens guide grooves 43 and 44 are provided corresponding to the grooves 42, respectively. In this embodiment, both the lens guide grooves 43 and 44 are linear grooves in the optical axis direction. Guide pin 35 is located in front group cam groove 41
Lens guide groove 43 and the guide pin 36
Is inserted across the rear group cam groove 42 and the lens guide groove 44.

The shapes of the front group cam groove 41 and the lens guide groove 43, and the rear group cam groove 42 and the lens guide groove 44 are respectively the movements of the cam ring 22 and the lens guide ring 24 in the optical axis direction as the cam ring 22 rotates, The relative rotation of the cam ring 22 and the lens guide ring 24 allows the movable lenses 15 and 16 to be given a predetermined locus of movement in the optical axis direction. In FIG. 6, a section l1 between the front group cam groove 41 and the rear group cam groove 42 is a zooming section, l2 is a macro transition section following the tele end of the zooming section l1, and l3 is a storage section following the wide end of the zooming section l1. Is.

The guide pins 35 and 36 (hence the cam grooves 41, 42 and the lens guide grooves 43, 44) are at least three.
This is to prevent the rear group lens frame 31 and the front group moving frame 34 from being fitted to the lens guide ring 24 in a long length, and thus to prevent them from collapsing with respect to the optical axis. Therefore, when the fitting length can be made long, or in the case of the structure in which the lens group is guided by the guide pole, and there is no risk of falling, the number of guide pins may be one or two.

In the present zoom lens barrel having the above-described configuration, when the male helicoid 20 is rotated in the forward and reverse directions, the female helicoid 18 meshing with the male helicoid 20 is fixed. While rotating according to the lead, it moves in the optical axis direction, and the lens guide ring 24 also moves in the optical axis direction.

The cam ring 22 comes to the specific rotation position, and at the notch 45,
After the screwing engagement of the male helicoid 20 with the female helicoid 18 is released, when the rotation direction is reversed, the end face of the male helicoid 20 meets the end face 46 of the female helicoid 18 facing the notch 45, but the helicoid mountain 20a of the male helicoid 20 is encountered. The end surface of is guided to the helicoid groove 18b by the inclined surface 46a. Therefore, the male helicoid 20 meshes with the female helicoid 18 in a normal state to smoothly move the cam ring 22 in the optical axis direction.

As the lens guide ring 24 moves in the optical axis direction, the cam grooves 41, 42
By the relationship between the lens guide grooves 43 and 44, the cam ring 22 rotates with respect to the lens guide ring 24, and the relative rotation causes the movable lenses 15 and 16 to move in the optical axis direction. by this,
The movable lenses 15 and 16 can be moved from the retracted state in FIG. 3 to the telephoto end state in FIG. 5, and even in the retracted state, the cam ring 22 and the lens guide ring 24 do not project,
Storage length is extremely short.

The effect of shortening the storage length is that the cam ring 22 advances and retreats in the optical axis direction as the cam ring 22 rotates, and the lens guide ring 24 moves the cam ring 22.
Moving in the optical axis direction together with, moving lenses 15 and 16 are supported by the cam ring 22 and the lens guide ring 24,
Also, in order to move the movable lenses 15 and 16 in the optical axis direction by the relative rotation of the cam ring 22 and the lens guide ring 24, the shapes of the front group cam groove 41, the rear group cam groove 42, and the lens guide grooves 43 and 44 are determined. It comes from being able to do. The cam ring 22 and the lens guide ring 24 can be shorter than the moving amount of the moving lenses 15 and 16, and the overall thickness can be reduced.

In other words, according to the present embodiment, the amount of movement of the movable lenses 15 and 16 in the optical axis direction is first secured by the amount of movement of the cam ring 22 in the optical axis direction, that is, the lead of the helicoid peak 20a of the male helicoid 20. It is possible to compensate for this shortage of the movement amount due to the lead by the front group cam groove 41 and the rear group cam groove 42. Alternatively, if the amount of movement of the helicoid crest 20a due to the lead is larger, the excess amount of movement may be subtracted by the front group cam groove 41 and the rear group cam groove 42.

The relationship between the lead of the helicoid crest 20a and the front group cam groove 41 and the rear group cam groove 42 is particularly clear when referring to the storage section 13 of the rear group cam groove 42. The storage section 13 is oriented on the cam ring 22 in the direction orthogonal to the optical axis. If the cam ring 22 only rotates, the moving lens 16 cannot be retracted. However, in this embodiment, the cam ring 22 itself moves along with the rotation in the optical axis direction, and
Since the moving lens 16 is supported on the rear lens 22,
Even if 42 is provided in the plane orthogonal to the optical axis, the cam ring
With the rotation of 22, the moving lens 16 can be retracted to the storage position. This means that the front group cam groove 41 and the rear group cam groove 42 formed in the cam ring 22 can be laid down as a whole (the inclination angle from the optical axis direction can be increased), and thus the front group cam groove 41. The length of the rear group cam groove 42 in the optical axis direction can be shortened to shorten the cam ring 22, and the moving accuracy of the moving lenses 15 and 16 can be improved.

The macro transition section l2 of the cam grooves 41 and 42 is inclined in the same direction as the inclination direction of the helicoid crest 20a, but this is because the lens movement amount from the tele end is small.

In the above embodiments, the lens guide ring guide groove 27 and the lens guide grooves 43 and 44 are all formed as straight grooves. Forming these with straight grooves has the advantage of facilitating the machining of these grooves and the setting of the shapes of the front group cam groove 41 and the rear group cam groove 42. It does not prevent forming the lens guide grooves 43 and 44 into a shape other than the linear grooves. In short, the rotation of the cam ring 22 causes the lens guide ring 24 to move together in the optical axis direction (including rotation at this time), and the relative rotation of the cam ring 22 and the lens guide ring 24 causes the movement of the moving lens 15 The shapes of the lens guide ring guide groove 27, the lens guide grooves 43, 44, the front group cam groove 41, and the rear group cam groove 42 are determined so that 16 moves along the optical axis along a predetermined locus. Good.

In the embodiment, the male helicoid 20 and the cam ring 22 are composed of separate members, and these are fixed with the fixing screw 21, but
These can be integrally molded with a resin material. Further, in the embodiment, the moving lenses are the front and rear two groups, but the present invention can of course be applied to a zoom lens barrel having three or more moving lenses. In this case, a cam groove for each moving lens may be formed in the cam ring 22. Such a zoom lens barrel can be used, for example, as an interchangeable lens for a higher-grade single-lens reflex camera.

“Effect of device” As described above, the zoom lens barrel of the present invention has the helicoid groove end face of the female helicoid facing the notch of the fixed cylinder or the end face of the male helicoid of the rotating cylinder, and the helicoid groove between the adjacent helicoid mountains. Since the inclined surface gradually increases the groove width, this inclined surface guides the end surface of the helicoid mountain of the male helicoid from the end surface of the female helicoid facing the notch to the helicoid groove with which the helicoid should mesh. Therefore, the male and female helicoids mesh with each other in a normal state, and the rotary cylinder can be smoothly moved in the optical axis direction.

[Brief description of drawings]

FIG. 1 is a perspective view of a cam ring and a female helicoid forming a zoom lens barrel according to the present invention, FIG. 2 is an enlarged perspective view showing a notched portion of the female helicoid, and FIG. 3 is a male helicoid meshing with the female helicoid. 4 is a schematic enlarged development view showing the state
1 to 6 are upper half sectional views showing an embodiment of a zoom lens barrel, FIG. 4 is a stored state, FIG. 5 is a wide end state,
FIG. 6 is a view showing a tele end state, and FIG. 7 is a development view of a cam ring, a lens guide ring and a cam ring helicoid. 11 …… Camera body, 12 …… Fixed barrel, 15,16 …… Moveable lens, 18 …… Female helicoid (outer helicoid), 18a…
Helicoid mountain, 18b Helicoid groove, 20 Male helicoid (inner helicoid), 20a Helicoid mountain, 20b
...... Inclined surface, 22 ...... Cam ring, 24 ...... Lens guide ring, 26 ...
… Straight guide plate, 27 …… Lens guide ring guide groove, 30 …… Front group lens frame, 31 …… Rear group lens frame, 32 …… Shutter block, 33 …… Helicoid ring, 34 …… Front group moving frame, 3
5, 36 …… Guide pin, 41 …… Front group cam groove, 42 …… Rear group cam groove, 43,44 …… Lens guide groove, 45 …… Notch, 46…
… End faces, 46a, 46b …… Sloping surfaces.

Claims (2)

[Scope of utility model registration request] 1. A pair of cylindrical bodies connected by screwing a helicoid, wherein at least one cylindrical body has a cutout part in which a part of the helicoid peak is removed, and the cutout part is In the zoom lens barrel through which the helicoid mountain of the cylindrical body or the end of the helicoid mountain passes, at the end of the helicoid mountain facing the notch, an inclined surface gradually expanding the interval between the adjacent helicoid mountains toward the notch. A zoom lens barrel characterized by being formed. 2. The zoom lens barrel according to claim 1, wherein an inclined surface whose height gradually decreases toward the cutout is formed at an end of the helicoid mountain facing the cutout.