JP2000147352A - Variable focal distance lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the miniaturization of a three-group type variable focal distance lens barrel capable of alternately executing a power varying operation and a focusing operation in accordance with the extension/retreat of a lens barrel. SOLUTION: A 1st group barrel 4 and a 3rd group lens frame 8 are held by a straight advance guide barrel 5 for holding a 2nd group lens frame 6 so that they may be moved in an optical axis direction. A 2nd driving barrel 3 is attached to the barrel 5 so that it may be freely rotated around the optical axis. A 1st driving barrel 2 is engaged with a fixed barrel 1, and when the 1st driving barrel 2 is rotated around the optical axis and extended, the barrel 5 is linearly moved toward an object, on the other hand, the 2nd driving barrel 3 is relatively rotated around the optical axis with reference to the barrel 5. In this case, the 3rd group lens frame 8 is relatively moved in the optical axis direction by the cam groove 3d formed at the inner surface of the barrel 3 with reference to the guide barrel 5, and also, the 1st group barrel 4 is relatively moved in the optical axis direction by the compound lead screw 3f formed at the inner surface of the 2nd driving barrel 3 with reference to the guide barrel 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable focal length lens barrel, and more particularly to a variable focal length lens barrel suitable for being applied to a three-group type variable focal length lens.

[0002]

2. Description of the Related Art A variable focal length lens barrel incorporated in a lens shutter camera has been proposed. A lens barrel extending mechanism that alternately repeats a variable power operation and a focus adjustment operation as the lens barrel is extended and retracted is proposed. Have been. According to such a lens barrel extending mechanism, an actuator for changing the magnification of the lens barrel (hereinafter, this actuator is referred to as a “magnification actuator”) and a lens are driven for focus adjustment. (Hereinafter, this actuator is referred to as a “focusing actuator”) in the present specification, which is advantageous for reducing the manufacturing cost and reducing the size and weight of the camera.

As described above, in the variable focal length lens barrel in which the variable power operation and the focus adjustment operation are alternately repeated, the composite focal length of the photographing lens is changed by changing the distance between a plurality of lens groups provided inside. A so-called two-group type has been used as a configuration for changing.

In the above-described variable focal length lens barrel having a two-group type configuration, the first-group lens and the second-group lens are driven according to independent movement trajectories, and the zooming operation and the focus adjustment operation are alternately repeated. Specifically, the first group lens is driven to extend and retract by the helicoid mechanism, while the second group lens is driven by a cam having a zigzag meandering cam profile having a plurality of inflection points, and the first group lens is moved between the first group lens and the first group lens. The relative distance changes.

When the variable focal length lens barrel is driven, for example, from the short focal length side to the long focal length side, the focal length changes → focal plane movement → focal length change → focal plane movement according to the meandering of the cam groove. repeat. By using this movement of the focal plane for focus adjustment, it is possible to share the variable power actuator and the focusing actuator.

In the variable focal length lens barrel described above, since the focal length changes intermittently with the zooming operation, the photographer sets the variable focal length lens barrel to the wide end (the shortest focal length). It cannot be set to an arbitrary focal length between the state (state) and the telephoto end (state where the focal length is the longest). However, by appropriately increasing the inflection point of the profile of the cam groove, the photographer can set the intended angle of view and operate the camera with almost no uncomfortable feeling.

In order to increase the zoom ratio of the variable focal length lens, the two-group type described above has a problem that the open F number on the long focal length side tends to be large (dark). In order to solve this problem, it is desirable that a variable focal length lens having a high zoom ratio has a three-group configuration.

[0008]

When the variable focal length lens barrel is of a three-group type, for example, one driving cylinder is provided with a cam groove for driving the second and third lens groups in the optical axis direction. There is a method of providing. In this method, 1
The driving cylinder on which the group lens is fixed is driven in the optical axis direction by a helicoid mechanism, and at the same time, the second and third group lenses are driven by the cam grooves, respectively, to perform a zoom operation.

However, in the case where the variable power actuator and the focusing actuator are shared by the three-group type variable focal length lens barrel, the variable focal length lens barrel becomes large for the reasons described below. There was a problem.

When the second and third lens groups, which are held movably in the optical axis direction within one moving frame, are driven by a cam groove formed in one cam cylinder, a variable power actuator and a focusing actuator are required. Independently, the cam grooves for the second and third lens groups can be provided so as to overlap in the optical axis direction. because,
In most cases, the profile of the cam groove for driving the second and third lens groups has no inflection point, and even if there is an inflection point, the undulation is slight. This is because the cam grooves for the three lens groups can be provided alternately so as not to cross each other. In other words, two types of cam grooves are provided in the optical axis direction, so that the length of the moving frame in the optical axis direction can be reduced.

On the other hand, when the variable magnification actuator and the focus actuator are used in common, the profile of the cam groove zigzags as described above, so that the cam grooves for driving the second and third lens groups are arranged in the optical axis direction. It is difficult to provide them in an overlapping manner. For this reason, in order to provide the cam grooves for the second and third lens groups in one cam cylinder, the cam grooves for the second and third lens groups are provided apart from each other in the optical axis direction.
It is necessary that both cam grooves do not cross each other. Then, the cam barrel becomes longer and the length when the variable focal length lens barrel is collapsed becomes longer, and the camera cannot be made thinner.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size of a three-unit type variable focal length lens barrel capable of alternately performing a zooming operation and a focus adjusting operation as the lens barrel is extended and retracted. I do.

[0013]

FIG. 2 shows an embodiment of the present invention.
The following invention will be described in association with. (1) The invention described in claim 1 holds the second lens group 6 and is disposed behind the first lens group 4 and the second lens group 6 disposed in front of the second lens group 6. Moving frame 5 for holding the third lens group 8 to be moved in the optical axis direction, respectively.
A first cam groove 2c is provided on the inner surface of the cylinder, and the moving frame 5 is driven in the optical axis direction by a moving amount determined based on a rotation angle around the optical axis and a profile of the first cam groove 2c. A helicoid screw 3f having a valley of a first depth on the inner peripheral surface of the cylinder and a bottomed second cam groove 3d having a second depth greater than the first depth; The first group lens 4 is moved by the moving frame 5 by a moving amount determined based on the rotation angle around the optical axis and the lead of the helicoid screw 3f.
And the third lens group 8 is moved in the optical axis direction with respect to the moving frame by a moving amount determined based on the rotation angle around the optical axis and the profile of the second cam groove 3d. The above-described object is achieved by having the second drive cylinder 3 that is driven relatively. (2) According to the second aspect of the present invention, the movable frame 5 allows the first lens group 4 and the third lens group 8 to move relative to the movable frame 5 along the optical axis direction, while rotating around the optical axis. Are further provided with straight guide portions 5b and 5d for restricting relative movement along the direction of. (3) The first, second, and third lenses are provided as the first drive cylinder 2 and the second drive cylinder 3 rotate around the optical axis and extend the moving frame 5. The groups 4, 6 and 8 are relatively close to the first shooting angle of view at an angle of view substantially equal to the first shooting angle of view from a position where a sharp image of a subject located at infinity at the first shooting angle of view is formed on the film surface. A sharp image of a subject located at infinity at a second shooting angle of view smaller than the first shooting angle of view is formed on the film surface through a position where a sharp image of the subject located at a distance is formed on the film surface. Is driven continuously from a position where an image is formed on the film surface to a position where a sharp image of a subject located at a relatively short distance at an angle of view substantially equal to the second photographing angle of view is formed on the film surface.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and operation of a variable focal length lens barrel according to an embodiment of the present invention will be described first, followed by details of the components constituting the variable focal length lens barrel. And the details of the variable power operation and the focusing operation of the variable focal length lens barrel will be described.

FIG. 1 is an exploded view of main components of the variable focal length lens barrel according to the embodiment of the present invention, and FIG. 2 is a longitudinal sectional view taken along the photographing optical axis. It will be described with reference to FIG.

In FIG. 1, a flange 1f is provided around the fixed cylinder 1, and is fixed to the camera body via the flange 1f. A female helicoid screw 1a is formed on the inner periphery of the fixed cylinder 1.

A male helicoid screw 2a screwed with the female helicoid screw 1a is formed on the outer peripheral surface of the first driving cylinder 2, and a spur gear (gear) 2b meshing with the driving gear 15 is formed on a peak of the male helicoid screw 2a. Are formed. That is, the male helicoid screw 2a has both a function as a helicoid screw and a function as a gear. First
On the inner peripheral surface of the drive cylinder 2, three cam grooves 2c and six straight guide grooves 2d are formed.

On the outer peripheral surface of the second drive cylinder 3, the first drive cylinder 2
The protrusions 3a engaging with the six rectilinear guide grooves 2d are provided at six places, and a composite lead screw 3f described later in detail is provided on the inner peripheral surface. A groove 3d is provided.

Six composite lead screws 3f of the second drive cylinder 3
A first-group lens 101 is incorporated and fixed to the first-group cylinder 4 having six male helicoid screws 4a on the outer periphery, which are screwed with the first group lens. On the inner peripheral surface of the first group cylinder 4, two or three (two cases are shown in FIG. 1) protrusions formed on the outer peripheral surface of the linear guide cylinder 5 so as to extend in the optical axis direction. Two or three rectilinear grooves 4b engaging with the portion 5b are formed, so that the first group cylinder 4 and the rectilinear guide cylinder 5 are prevented from moving relative to each other in the direction around the optical axis, while in the optical axis direction. Relative movement is possible.

Behind the straight guide cylinder 5, a flange 5g is provided.
Is formed, and a circumferential groove 5h is provided in the flange portion 5g. Three follower pins 5c are fixedly provided on the outer periphery of the flange portion 5g at positions that divide the circumference into three equal parts. A key 10 of a moving key 10 described later is
key groove 5e which engages with the optical groove b so as to be relatively movable in the optical axis direction.
Formed at the location. Three straight guide holes 5d and 5f are provided in the cylindrical portion of the straight guide cylinder 5 in the circumferential direction.

The shutter unit 7 includes a second group lens 10
The second group lens frame 6 holding the lens 2 is integrally fixed by screws (not shown). In front of the shutter unit 7, FIG.
As shown in FIG. 2, a groove 7a is provided, and one end of a cylindrical bellows 11 molded of light-shielding silicone rubber or the like and stretchable in the optical axis direction is fixed to the groove 7a. The other end (the subject side end) of the bellows 11 is fixed to the tip end of the first group cylinder 4 by a retaining ring 13 as shown in FIG. The bellows 11 is for preventing light incident from the first lens unit 101 from reaching the film surface through the outer peripheral portion of the shutter unit 7.

As shown in FIG. 1, the third group lens 103
The third group lens frame 8 and the second group lens frame 6 described above are assembled into the straight guide cylinder 5 with an urging spring 9 interposed therebetween. The three guide pins 6a inserted into the second group lens frame 6 engage with the straight guide holes 5f, and the three follower pins 8a inserted into the third group lens frame 8 and the straight guide holes 5d.
Are engaged, and the two lens frames 6 and 8 are held in the rectilinear guide tube 5 so as to be movable in the optical axis direction. At this time, the biasing spring 9
As a result, the second group lens frame 6 is placed on the subject side,
Are biased toward the film.

The above-described first group cylinder 4 and second driving cylinder 3 are screwed together and combined, and further, as described above, the straight movement guide incorporating the second group lens frame 6, the urging spring 9, the third group lens frame 8 and the like. The lens holding unit LH is completed by combining the cylinders 5 such that the rectilinear grooves 4b and the protrusions 5b engage with each other.
At this time, a projection 3g that engages with a circumferential groove 5h provided in the flange portion 5g is formed on the inner periphery near the film-side end surface of the second drive cylinder 3 as shown in FIGS. By incorporating the straight guide cylinder 5 into the second drive cylinder 3, the circumferential groove 5h and the projection 3g are engaged by snap fitting. The second drive cylinder 3 and the linear guide cylinder 5 assembled as described above move integrally in the optical axis direction, and are relatively rotatable in the rotation direction around the optical axis. When the straight driving guide cylinder 5 is fixed and the second drive cylinder is rotated around the optical axis, the first group cylinder 4 whose rotation is restricted by the straight driving guide cylinder 5 is controlled.
, The second drive cylinder 3 relatively rotates, and the first group cylinder 4 moves straight along the optical axis direction by the action of the male helicoid screw 4a and the composite lead screw 3f. At this time, the action of the follower pin 8a inserted into the third lens group frame 8 and the cam groove 3d of the second drive cylinder 3 causes the third lens group frame 8 to move straight in the straight guide cylinder 5.

Returning to FIG. 1, the lens holding unit LH is incorporated in the first drive cylinder 2, and at this time, the projection 3a and the guide groove 2d engage, and the follower pin 5c and the cam groove 2c engage. A female screw 2e shown in FIG. 2 is formed on the inner periphery near the film-side end surface of the first drive cylinder 2, and the fixed member 12 into which the moving key 10 is inserted is screwed to the female screw 2e. The fixed key 12 allows the moving key 10 to rotate relative to the first driving cylinder 2 without falling out of the first driving cylinder 2. In other words, the first driving cylinder 2 and the moving key 10 move integrally in the optical axis direction, and are relatively rotatable in the rotation direction around the optical axis. In a state in which the moving key 10 is incorporated in the first driving cylinder 2, the key 10 b of the moving key 10 is a key groove 5 provided on the inner periphery of the linear guide cylinder 5.
e.

As described above, the lens holding unit LH
The male helicoid screw 2a provided on the outer peripheral surface of the first drive cylinder 2 in which the moving key 10 and the like are assembled is screwed into the female helicoid screw 1a of the fixed cylinder 1, and the moving key 1
The guide frame 14 is fixedly mounted at the side of the film No. 0 with four screws 20. The guide frame 14 is provided with a convex portion 14b, and the convex portion 14b engages with an edge 1c of an opening 1b provided in the fixed cylinder 1 so as to extend in the optical axis direction. Convex part 14
The engagement of the edge b with the edge 1c restricts the rotation of the guide frame 14 around the optical axis, while allowing the guide frame 14 to move in the optical axis direction.

A drive gear 15 is rotatably attached to the above-mentioned opening 1b of the fixed cylinder 1. Drive gear 15
Rotate in a direction parallel to the optical axis. Drive gear 1
5 engages with a gear 2b engraved on a male helicoid screw 2a of the first driving cylinder 2, and the first driving cylinder 2 rotates within the fixed cylinder 1 in response to the rotation of the driving gear 15, so that the optical axis Move back and forth in the direction. The drive gear 15 has a sufficient tooth width so that the meshing does not come off even if the first drive cylinder 2 moves back and forth in the optical axis direction.

-Outline of the operation of the variable focal length lens barrel-As described above, when the first driving cylinder 2 moves back and forth in the optical axis direction while rotating inside the fixed cylinder 1, the guide groove 2d of the first driving cylinder 2
And the projection 3a of the second drive cylinder 3 are engaged,
The driving cylinder 3 is rotated by the first driving cylinder 2. Meanwhile, 1
The rotation of the group cylinder 4 around the optical axis is regulated by the straight guide cylinder 5, the straight guide cylinder 5 is regulated by the moving key 10, and the movement key 10 is moved linearly along the optical axis direction by the guide frame 14. .

In the following, the first drive cylinder 2, the third lens frame 8,
The movement of the fixed barrel 5, the second lens barrel 6, the second drive barrel 3, and the first barrel 4 in the optical axis direction will be described.

The first drive cylinder 2 has a female helicoid screw 1a.
In addition, the lead set by the male helicoid screw 2 a drives the front-rear drive in an amount proportional to the rotation angle of the first drive cylinder 2.

The linear guide cylinder 5 has a follower pin 5c fixed to the linear guide cylinder 5 and a cam groove 2c provided on the inner periphery of the first drive cylinder 2 engaged with each other. The front and rear driving is performed by an amount corresponding to the rotation angle of the first driving cylinder 2 and the rotation angle of the first driving cylinder 2. When the amount of movement along the optical axis direction with respect to the film surface is considered, the amount of forward / backward movement of the linear guide cylinder 5 is obtained by adding the amount of lift of the cam groove 2c to the amount of movement of the first drive cylinder.

Since the second drive cylinder 3 moves back and forth in the optical axis direction integrally with the rectilinear guide cylinder 5 as described above, the amount of movement is the same as the amount of movement of the rectilinear guide cylinder 5.

The first driving cylinder 2 is made up of a first driving cylinder 2 by a lead set by a composite lead screw 3f and a rectilinear groove 4b.
, That is, the front and rear drive of the amount corresponding to the rotation of the second drive cylinder 3 is performed. When the amount of movement along the optical axis direction with respect to the film surface is considered, the amount of forward / backward movement of the first group cylinder 4 is the sum of the amount of movement of the straight guide cylinder 5 and the amount of extension by the composite lead screw 3f.

The variable focal length lens barrel according to the present embodiment is a so-called collapsible variable focal length lens barrel. That is, when the power of the camera is turned on, the variable focal length lens barrel extends from the retracted state (retracted state) to the wide end, and then moves between the wide end and the tele end according to the operation of the focal length change switch by the photographer. , And the operation is performed. Hereinafter, in this specification, the operating range of the variable focal length lens barrel from the retracted state to the wide end position is referred to as a “retracted area”, and the area from the wide end to the telephoto end is referred to as a “photographing area”. Called.

The second group lens frame 6 is urged toward the subject by the urging spring 9 as described above, and the guide pin 6a fixed to the second group lens frame 6 has a straight guide hole 5f of the straight guide cylinder 5. Is engaged. When the variable focal length lens barrel is in the photographing area, the second lens group frame 6 moves together with the rectilinear guide barrel 5. The case where the variable focal length lens barrel is in the retracted area will be described in detail later. . At this time, the shutter unit 7 is pushed by the first group cylinder 4, whereby the second group lens frame 6 is retracted to the film surface side. FIG. 2 shows a state in which the variable focal length lens barrel is in a collapsed state, and the second lens group frame 6 is retracted to the film surface side.

The follower pin 8a fixed to the third lens frame 8 is provided with the straight guide hole 5 of the straight guide cylinder 5 as described above.
d and engages with a cam groove 3 d formed on the inner peripheral surface side of the second drive cylinder 3. Therefore, the third lens group frame 8 is
The longitudinal drive is performed by an amount corresponding to the rotation angle when the second drive cylinder 3 relatively rotates around the optical axis with respect to the linear guide cylinder 5 and the cam profile of the cam groove 3d. When the amount of movement in the optical axis direction is considered with reference to the film surface, the third group lens frame 8
Is the sum of the amount of movement of the straight guide cylinder 5 and the amount of lift of the cam groove 3d.

Summarizing the above description, when the variable focal length lens barrel according to the present embodiment performs a zooming operation,
Only the first driving cylinder 2 and the second driving cylinder 3 perform the extending / retracting operation with the rotation around the optical axis, and the other first-group cylinder 4, second-group lens frame 6, straight-moving guide cylinder 5, third-group lens The frame 8 and the like perform the extending / retracting operation without the rotation, that is, the straight traveling operation.

Here, the operation of the first-group lens 101, the second-group lens 102 and the third-group lens 103 will be described by taking as an example a case where the variable focal length lens barrel performs a magnification operation from the wide end to the telephoto end. In the variable focal length lens barrel according to the present embodiment, the first group lens 101, the second group lens 102
The third group lens 103 is basically held with the rectilinear guide tube 5 as a core. The straight guide cylinder 5 is provided with the male helicoid screw 2a and the cam groove 2c of the first drive cylinder 2.
Is fed out by the action of. At this time, the first-group cylinder 4 and the third-group lens frame 8 move relative to the rectilinear guide cylinder 5 by the action of the composite lead screw 3f and the cam groove 3d provided on the inner surface of the second drive cylinder 3. The second lens group frame 6 moves integrally with the straight guide cylinder 5. By a combination of the above operations, the first group lens 101, the second group lens 102, and the third group lens 103 move to the subject side with the variable power operation of the variable focal length lens barrel, and the first group lens 101 and the second group lens 102, the group distance between the second group lens 102 and the third group lens 103 is changed.

Following the above description of the configuration and the schematic operation of the variable focal length lens barrel according to the embodiment of the present invention, details of the main components constituting the variable focal length lens barrel will be described.

FIG. 3 (a) is an exploded view of the inner peripheral surface of the first drive cylinder 2, wherein the upper side of FIG. 3 (a) is on the subject side, and the lower side is a film. Corresponds to the surface side. On the inner peripheral surface of the first driving cylinder 2, six guide grooves 2 d engaging with the projections 3 a of the second driving cylinder 3 and three cams engaging with follower pins 5 c fixed to the linear guide cylinder 5. A groove 2c is formed.

The first drive cylinder 2 is manufactured by molding a plastic or the like, and the groove width of the cam groove 2 c is tapered so as to increase toward the center of the first drive cylinder 2. This taper prevents undercut (interference between the mold and the product when the product is removed from the mold) when molding the second drive cylinder 3.

FIG. 3B showing a cross section BB of FIG. 3A.
The reason why the number of the guide grooves 2d is twice the number of the cam grooves 2c will be described with reference to FIG. Since the depth of the cam groove 2c is provided to be deeper than the depth of the guide groove 2c, the guide groove 2d is divided at the intersection of the cam groove 2c and the guide groove 2d. Guide groove 2d
Is smaller than the width of the cam groove 2c in the optical axis direction. Therefore, as shown in FIG. 3B, when the projection 3a engaged with the guide groove 2d moves upward in FIG.
As shown in FIG. 3 (c), the engagement between the projection 3a and the guide groove 2d is released when approaching the portion divided by the cam groove 2c. If the cam groove 2c and the guide groove 2
d, the same number of cam grooves 2c and guide grooves 2
If d is provided at equal intervals, the engagement between the projection 3a and the guide groove 2d will be released simultaneously.

Therefore, in the variable focal length lens barrel according to the present embodiment, three cam grooves 2c are provided, whereas six guide grooves 2d are provided twice. By providing the guide grooves 2d twice as many as the number of the cam grooves 2c, even if the engagement of the projections 3a is disengaged with the odd-numbered guide grooves 2d counted from the left in FIG. Can be maintained. The arrangement positions of the guide grooves 2d do not necessarily have to be provided at positions where the circumference is equally divided into six, and may be provided at unequal pitches as shown in FIG. In short, the projection 3a is engaged with any one of the guide grooves 2d among the plurality of guide grooves 2d.
The arrangement pitch of the guide grooves 2d may be determined so that all the engagements do not come off at the same time.

In this embodiment, the three odd-numbered guide grooves 2d and the even-numbered three guide grooves 2d counted from the left in FIG. It is provided at a position where it is equally divided into three. That is, the circumferential pitch of the arrangement position of the guide groove 2d is P1, P2, P1,
P2,... Are repeated. By providing the guide grooves in this manner, the engagement between the even-numbered guide grooves 2d and the projections 3a is maintained even when the engagement between the odd-numbered guide grooves 2d and the projections 3a is released. In addition, since the first drive cylinder 2 and the second drive cylinder are always engaged at a position that divides the circumference into approximately three equal parts, the support balance is excellent. By making the support balance excellent as described above, the first drive cylinder 2 and the second drive cylinder 3 can be relatively smoothly moved.

In the above example, the number of guide grooves 2d provided together with the three cam grooves 2c is set to 3, for example, the arrangement intervals of the guide grooves 2d are made unequal, and
) Can be prevented from coming off at the same time. Alternatively, for example, by providing four guide grooves 2d for the three cam grooves 2c, it is possible to prevent all the projections 3a from coming off at the same time. However, in this case, when the projection 3a and the guide groove 2d are disengaged somewhere, the first
The engagement position between the driving cylinder 2 and the second driving cylinder 3 may be deviated on the circumference, and the support balance may not be good. Therefore, the guide grooves 2d are provided in an integral multiple of the number of the cam grooves 2c, and the engagement between the guide grooves 2d and the projections 3a is always maintained at a position where the circumference is substantially divided into three equal parts. It is desirable to set the arrangement position of the guide groove 2d as described above.

Although the example in which the number of the cam grooves 2c is three has been described, the number of the cam grooves 2c may be two or another number.

By making the length of the plurality of protrusions 3a in the optical axis direction longer than the groove width of the cam groove 2c, the above-mentioned design considerations are not required. However, the shortest dimension of the first driving cylinder 2 in the optical axis direction is the sum of the relative movement stroke of the first driving cylinder 2 and the second driving cylinder 3 in the optical axis direction and the length of the projection 3a in the optical axis direction. Since the length is determined, if the length of the projection 3a in the optical axis direction is increased, the length of the first drive cylinder 2 in the optical axis direction is also increased. For this reason, shortening the length of the projection 3a in the optical axis direction as described above is effective for shortening the entire length of the variable focal length lens barrel when retracted, and the above-described design considerations should be taken into consideration. desirable.

-Second Drive Cylinder-The composite lead screw 3f and the cam groove 3d formed on the inner peripheral surface of the second drive cylinder 3 will be described with reference to FIG. FIG. 4 is an exploded view of the inner peripheral surface of the second drive cylinder 3. The upper part of the figure corresponds to the subject side, and the lower part corresponds to the film side. The composite lead screws 3f1 to 3f6 are provided in a portion of a range A located on the film side of the second drive cylinder 3 shown in FIG.
A screw 3 provided in a range B located on the subject side of the second drive cylinder 3 and having a second lead smaller than the first lead
c1 to 3c6 are connected via bent portions 3e1 to 3e6, respectively.

Hereinafter, in this specification, the screws having the first and second leads are simply referred to as “first lead screw” and “second lead screw”. As can be seen from FIG. 4, in the present embodiment, the composite lead screws 3f1 to 3f6 are six multi-start screws.

The shapes of the composite lead screws 3f1-3f6 will be described.
Among the first lead screws 3b1 to 3b6 constituting the above, the groove width of the valley portion differs between the odd-numbered and even-numbered subscripts.
Specifically, the first lead screws 3d1, 3d3 and 3d
The groove width of the valley of 5 is formed wider than the groove width of the valley of 3d2, 3d4, and 3d6. The reason will be described later.

The composite lead screw 3f1f is placed on the side of the range A of the composite lead screw 3f1-3f6, that is, on the film side.
Three cam grooves 3d1 to 3d3 of the same shape are provided at positions that divide the circumference into approximately three equal parts so as to overlap with 1 to 3f6.

FIG. 4B showing a BB section of FIG. 4A.
As shown in (1), the depth (dimension b) of the cam grooves 3d1 to 3d3 is formed to be deeper than the depth of the valley (dimension a) of the composite lead screws 3f1 to 3f6. Like the first drive cylinder 2, the second drive cylinder 3 is manufactured by molding of plastic or the like, and the second drive cylinder 3 has a second drive cylinder 3f1 to 3f6 having a valley groove width and a cam groove 3d1 to 3d3 groove width. The taper is formed so as to expand toward the center of the cylinder 3. With this taper, undercutting when molding the second drive cylinder 3 is prevented.

Referring to FIG. 5, six male helicoid screws 4a1 to 4a6 provided on the outer periphery of the first group cylinder 4 and screwed to the above-described composite lead screws 3f1 to 3f6 will be described. FIG. 5A shows an inner peripheral surface of the second driving cylinder 3 developed, and FIG.
2 male helicoid screws 4a1, 4a2
Are superimposed and illustrated. Hereinafter, an example in which the composite lead screw 3f1 and the male helicoid screw 4a1 are screwed together will be described. The cam groove 3d on the left side of the two-dot chain line AA in FIG.
Illustrations of 1, 3d2 are omitted.

FIG. 5B, which is an enlarged view of the male helicoid screw 4a1, shows the male helicoid screw 4a.
1 has first lead surfaces a and b screwed to the first lead screw 3b1, second lead surfaces c and d screwed to the second lead screw 3c1, and surfaces e and f orthogonal to the optical axis. Each of the male helicoid screws 4a1 to 4a6 is formed with a taper in accordance with the taper formed on the composite lead screw 3f1 to 3f6, and has a so-called trapezoidal screw thread shape, but illustration thereof is omitted.

Returning to FIG. 5A, the male helicoid screw 4
a1 is screwed with the first lead screw 3b1 in the collapsed region from the collapsed position to the vicinity of the wide end, and screwed with the second lead screw 3c1 in the photographing region from the W (wide) end to the T (tele) end. I do.

The male helicoid screw 4a1 is screwed from the first lead screw 3b1 to the second lead screw 3c1, or vice versa. The male helicoid screw 4a1 is screwed from the second lead screw 3c1 to the first lead screw 3b1. The process of switching to the state will be described with reference to FIG. FIG. 5C shows the first lead screw 3b1 and the bent portion 3e.
FIG. 1 is a partially enlarged view showing a second lead screw 3c1 together with a male helicoid screw 4a1. In the process in which the variable focal length lens barrel extends from the retracted position to the wide end, the second drive barrel 3 moves to the left in the drawing. The male helicoid screw 4a1 is pushed by the slope p of the first lead screw 3b1 and moves upward (subject side) in the figure. In the process of retracting the variable focal length lens barrel from the wide end to the retracted position, the second drive barrel 3 moves rightward in the figure. The male helicoid 4a1 is the slope q of the second lead screw 3c1.
And move downward (film side) in the figure. In any case, the male helicoid 4a1 is
e1 to a state in which the first lead screw 3b1 is screwed with the second lead screw 3c1 or a second state
From the state in which the first lead screw 3c2 is screwed, the first lead screw 3
The state is switched to a state of screwing with b1.

As described above, the groove widths of the valleys of the first lead screws 3b1, 3b3 and 3b5 are 3b2 and 3b.
The groove width is configured to be wider than the groove width of the valleys b4 and 3b6.
Therefore, for example, the size of the male helicoid screw 4a2 is different from that of the male helicoid screw 4a1, but the shape is similar to that of the male helicoid screw 4a1, so that the illustration and description are omitted.

Referring to FIG. 4 again, the reason why the groove width of the valley is different between the odd-numbered and even-numbered composite lead screws 3f1 to 3f6 will be described. Originally, composite lead screws 3f1-3f6 and cam grooves 3b1-3
The composite lead screw 3f1 is not provided so as to overlap with the b3.
It is structurally simpler to provide the 3f6 and the cam grooves 3b1 to 3b3 separately in the front-rear direction along the optical axis. However, if the dimension of the second drive cylinder in the optical axis direction is extended in this manner, the variable focal length lens barrel becomes long, and the thickness of the camera when collapsed cannot be reduced. Therefore, as shown in FIG. 4, the composite lead screws 3f1-3f6 and the cam grooves 3b1-3
b3 is provided in an overlapping manner.

As described above, the composite lead screws 3f1-3f
When the 6 and the cam grooves 3b1 to 3b3 are provided so as to overlap with each other, the screw grooves of the composite lead screws 3f1 to 3f6 are divided by the cam grooves 3b1 to 3b3 as shown in FIG. For this reason, the male helicoid screws 4a1 to 4a6 may be disengaged from the composite lead screws 3f1 to 3f6 at the same time for the same reason as described for the first drive cylinder 2 (FIG. 3). In order to prevent such a problem from occurring, the three cam grooves 3b1 to 3b3 are provided, whereas the composite lead screws 3f1 to 3f6 are provided as integral multiples, and in this embodiment, twice as many as six. .

When the cam profiles of the cam grooves 3d1 to 3d3 meander as in the present embodiment, one composite lead screw is divided at a plurality of places depending on the cam profile, and the male helicoid screw is cut. There is a possibility that the engagement between the composite lead screws 3f1 to 3f6 and the composite lead screws 3f1 to 3f6 may be simultaneously released. In such a case, among the six composite lead screws 3f1 to 3f6,
It is effective to change the groove width at the valley portion depending on whether the suffix is odd or even. That is, by changing the groove width of the valleys, the composite lead screws 3f1 to 3f6 become cam grooves 3b1.
3b3, the position in the optical axis direction can be shifted, so that the male helicoid screws 4a1-4a
6 and the composite lead screws 3f1 to 3f6 can be designed so as not to be simultaneously disengaged.

When the variable focal length lens barrel according to the present embodiment is extended and retracted from the retracted region to the photographing region or from the photographing region to the retracted region, the male helicoid screws 4a1 to 4a6 are connected to the composite lead screws 3f1 to 3f6. The passage through the bent portions 3e1 to 3e6 has already been described.
That is, between the first lead screw 3b1-3b6 and the second lead screw 3c1-3c6, the male helicoid screw 4a1
When the engagement of 4a6 is switched, the bent portions 3e1-3e
6 plays an important role. That is, the bent portions 3e1-3e
Since the operation of the male helicoid screws 4a1 to 4a6 is largely switched after the male helicoid screws 4a1 to 4a6 pass through the portion 6, the bent portions 3e1 to 3e6 are prevented from being divided by the cam grooves 3b1 to 3b3. is important.

The bent portions 3e1-3e6 are formed in the cam grooves 3b1-3.
In order to prevent the composite lead screws 3f1 to 3f6 from being divided by b3, parameters such as the number of threads and the width of the thread groove may be considered when determining the shapes of the composite lead screws 3f1 to 3f6.

In the present embodiment, in consideration of the above-mentioned parameters, as shown in FIG. 4, all the bent portions 3e1 to 3e6 of the six composite lead screws 3f1 to 3f6 are divided by the cam grooves 3d1 to 3d3. I am trying not to be. Theoretically, among the six bent portions 3e1 to 3e6,
Male helicoid screw 4a1-4 if at least one remains
a6 should work. However, in reality, there are unstable factors such as a manufacturing error of the second drive cylinder 3 and looseness of fitting between the second drive cylinder 3 and the male helicoid screws 4a1 to 4a6 of the first group cylinder 4. Due to these instability factors, any of the male helicoid screws 4a1 to 4a6 approaching the portion where the bent portion is divided may come off from the thread groove. Therefore, these bent portions 3e1-3e
It is preferable that all the members 6 are not divided by the cam grooves 3d1 to 3d3 in order to obtain the certainty of the operation and to make the operation smooth.

The formation positions of the composite lead screws 3f1 to 3f6 and the cam grooves 3d1 to 3d3 on the inner peripheral surface of the second drive cylinder 3 will be described. A cam groove 3 for driving the third group lens frame 8 with respect to the formation positions of the composite lead screws 3f1 to 3f6 for extending and retracting the first group cylinder 4
The formation positions of d1 to d3 are on the film surface side as shown in FIG. The reason why the composite lead screws 3f1-3f6 and the cam grooves 3d1-3d3 are formed in the above-described positional relationship is to increase the strength of the variable focal length lens barrel. That is, when an external force in the optical axis direction acts on the first group cylinder 4 or the third group lens frame 8, the male helicoid screws 4a1 to 4a
6, composite lead screw 3f1-3f6, follower pin 8a
A shear stress is generated in the cam grooves 3d1 to 3d3.
At this time, assuming that the same external force acts in the optical axis direction, the male helicoid screws 4a1-4
a6 and the composite lead screws 3f1 to 3f6 generate a shear stress that is greater than the follower pin 8 and the cam grooves 3d1 to 3d.
3 is smaller than the shear stress generated. That is, the male helicoid screws 4a1 to 4a6 and the composite lead screws 3f1 to 3f6 can withstand greater external forces.

For this reason, in the variable focal length lens barrel according to the present embodiment, the first group barrel 4 exposed to the outside of the barrel is
While being engaged with the drive cylinder 3 by a helicoid screw, the third group lens frame 8 which is disposed on the film surface side inside the lens barrel and is less subjected to a large external force is driven by the cam.

By setting the formation positions of the composite lead screws 3f1 to 3f6 and the cam grooves 3d1 to 3d3 on the inner surface of the second drive cylinder 3 as described above, it is possible to increase the strength of the lens barrel constituent members exposed to the outside. Become. By providing the composite lead screws 3f1 to 3f6 and the cam grooves 3d1 to 3d3 so as to overlap each other in the optical axis direction, the total length of the second drive barrel 3 can be shortened. The size at the time of collapsing can be shortened and the camera can be downsized.

-Straight Guide Tube and Constriction of Shutter FPC-In FIG. 6, the second group lens frame 6, to which the shutter unit 7 is attached, the biasing spring 9, and the third group lens frame 8 are incorporated in the straight guide tube 5. Show the situation. Shutter unit 7
The middle portion 7c of the shutter FPC 7a for electrically connecting the camera body and a circuit board (not shown) of the camera body is
Is fixed via a FPC stopper 22 to a notch 5i provided in the flange portion 5g.

As described above, the rectilinear guide cylinder 5 has the rectilinear guide holes 5d and 5f, and the second group lens frame has the guide pins 6a engaged with the rectilinear guide holes 5f.
The follower pin 8a of the third lens group 8 has a straight guide hole 5d.
And are supported so as to be movable in the direction of the optical axis in the straight guide cylinder 5 respectively. Then, the urging spring 9 interposed between the second group lens frame 6 and the third group lens frame 8 moves the second group lens frame 6 downward (subject side) in the figure and moves the third group lens frame 8 upward (in the figure). (The film surface side). A plurality of projections 5b are provided on the outer periphery of the straight guide cylinder 5 so as to extend in a direction parallel to the optical axis. As shown in FIG.
It engages with a rectilinear groove 4b formed inside the group cylinder 4. That is, the straight guide cylinder 5 is the first group cylinder 4 (the first group lens 101),
The function as a moving frame for holding the second group lens frame 6 (the second group lens 102) and the third group lens frame 8 (the third group lens 103) and the function as a straight guide for the first group cylinder 4 and the third group lens frame 103 are provided. Have both.

The shutter FPC 7a is formed with a constricted portion 7b whose width is partially reduced. Shutter FPC7
Although a plurality of conductive patterns are formed along the longitudinal direction of a, the width of each of the plurality of conductive patterns in the constricted portion 7b is also reduced. This is because the bending rigidity in the thickness direction of the constricted portion 7b is reduced as described below.

FIG. 7 is a longitudinal sectional view showing a state where the variable focal length lens barrel according to the present embodiment is located at the wide end. In FIG. 7, the second lens frame 6 includes an urging spring 9.
Is biased to the left (subject side) in the figure. That is, the second group lens frame 6 and the shutter unit 7 are in a state of being pressed to the subject side most within the moving range of the straight guide cylinder 5. When the photographing area, that is, the variable focal length lens barrel is located at the wide end to the tele end, the positional relationship between the straight guide cylinder 5, the second lens group frame 6, and the shutter unit 7 is maintained as shown in FIG. Is done. In this state, since the shutter unit 7 and the flange portion 5g of the straight guide guide cylinder 5 are farthest apart, the shutter FPC 7a is in a state where the slack is relatively small.

FIG. 8 is a longitudinal sectional view showing a state where the variable focal length lens barrel according to the present embodiment is in the retracted position. In the retracted state, the first-group cylinder 4 is retracted to a position where the first-group cylinder 4 substantially overlaps the linear guide cylinder 5 in the optical axis direction, and the second-group holding frame 6 is pushed toward the film surface by the retreated first-group cylinder 4. fall back. As the second group holding frame 6 retreats, the shutter unit 7 and the flange portion 5g of the straight guide cylinder 5 approach, and the slack amount of the shutter FPC 7a increases.

Incidentally, when the camera is not used, the variable focal length lens barrel is often in a retracted state. That is, the shutter FPC 7a is often in the state of FIG. Therefore, the shutter FPC 7a is easily bent. When the shutter FPC 7a is bent, when the variable focal length lens barrel is extended to the shooting range, the bent shape of the shutter FPC 7a is reduced to the second group lens frame 6.
Act as an elastic force that tries to retreat. If the elastic force of the shutter FPC 7a exceeds the force by which the urging spring 9 pushes the second group lens frame 6 toward the subject, the second group lens frame 6 falls down with respect to the optical axis, or the second group lens 102
The group spacing between the lens and the third group lens 103 changes, and the optical performance decreases. On the other hand, in the variable focal length lens barrel according to the present embodiment, the above-described constricted portion 7b (FIG. 6) is located at the bent portion of the shutter FPC 7a.
Therefore, the bending stiffness of the shutter FPC 7a is reduced, so that the above-described problem can be prevented. Of course, it is possible to suppress the above-described problem by increasing the urging force of the urging spring 9, but if the urging force of the urging spring 9 is increased, the motor for driving the variable focal length lens barrel to change the magnification is driven. The load increases. Therefore, it is desirable to reduce the rigidity of the shutter FPC 7a as described above.

The length of the constricted portion 7b is a small amount as compared with the entire length of the shutter FPC 7a. The amount of increase in the conduction resistance caused by reducing the width of the conductive pattern at the constricted portion 7b is equal to the total length of the shutter FPC 7a. The width can be reduced as compared with the case where the width of the conductive pattern is narrowed over the entire width. Therefore, the supply current to the shutter actuator that requires a relatively large drive current is not limited,
A sufficient driving force of the shutter actuator can be obtained.

-Fixed tube-FIG. 9A is a front view showing the fixed tube 1 viewed from the subject side, and FIG. 9B is a view showing a cross section BB of FIG. 9A. It is. As shown in FIG. 9A, the fixed cylinder 1
A notch-shaped groove 1d is provided in a part of the female helicoid screw 1a provided on the inner surface of the cylindrical portion. The inner surface 1e of the groove 1d is provided at a position farther from the optical axis than the root diameter of the female helicoid screw 1a. The groove 1d is shown in FIG.
And a so-called encoder board for electrically detecting the extension position of the variable focal length lens barrel in the optical axis direction, as described later, and the above-described shutter FPC 7a provided. It is a space to do. The groove 1d also serves as a moving space for the encoder brush that slides on the surface of the encoder substrate in the optical axis direction, as described later.

In the cylindrical portion of the fixed cylinder 1, an opening 1b is provided at a position substantially opposed to the groove 1d. Shafts provided at both ends of the drive gear 15 for rotatingly driving the first drive cylinder 2 are rotatably supported by holes 1g and 1h of the fixed cylinder 1. As described above, the driving gear 15 and the male helicoid screw 2 of the first driving cylinder 2 are connected via the opening 1b.
The gear 2b engraved on a is engaged.

Referring again to FIG. 8, the surroundings of the groove 1d of the fixed cylinder 1 will be described. An encoder board 24 is provided on the inner surface 1e of the groove 1d. The pattern formed on the encoder board 24 may simply generate a 1-bit signal that repeats ON / OFF, or a pattern in which the ON / OFF phase is shifted by 180 degrees with respect to the above-described pattern. Further, a so-called two-phase clock signal-like pattern may be added. When the drive gear 15 (FIG. 2) is driven by a motor (not shown) and the first drive cylinder 2 moves back and forth in the optical axis direction, the guide frame 14
The encoder brush 17 fixed to the encoder brush mounting portion 14a moves in the optical axis direction and slides. A signal generated in response to the movement of the encoder brush 17 in the optical axis direction is input to a control circuit (not shown). This signal is
It is used to detect the extension position of the variable focal length lens barrel, or to obtain focal length information, open F-number information, and the like.

FPC 2 connected to encoder board 24
4a is fixed to the fixed cylinder 1 by the fixing member 1e together with the shutter FPC 7a. Shutter FP in groove 1d
C7a is disposed so as to be located in a space between the encoder brush 17 and the first drive cylinder 2.

The behavior of the shutter FPC 7a associated with the variable power operation of the variable focal length lens barrel according to the present embodiment will be described with reference to FIGS. In FIG. 7 showing the case where the variable focal length lens barrel is at the wide end, the rectilinear guide barrel 5 is located at a position relatively close to the film surface. A portion of the shutter FPC 7a between the FPC stopper 22 and the fixing member 1e has a groove 1
d. Figure 1 shows the variable focal length lens barrel
As shown at 0, the second
The drive cylinder 3 (the straight guide cylinder 5) and the first drive cylinder 2 extend toward the subject. Thus, the shutter FPC 7a housed in the groove 1d moves into the lens barrel. At this time, the shutter FPC 7a moves between the first drive cylinder 2 and the encoder brush 17 in the groove 1d. That is, the shutter FPC 7a undulates in the groove 1d and
The shutter FPC 7a is pushed away by the encoder brush attachment portion 14a of the guide frame 14 even if the contact is made, so that the contact between the encoder brush 17 and the encoder substrate 24 is not hindered.

The groove 1d is formed in a box shape outside the root diameter of the female helicoid screw 1a of the fixed cylinder 1, so that the cylindrical portion of the fixed cylinder 1 is not divided. For this reason, the rigidity of the cylindrical portion can be suppressed from lowering as compared with the case where the cylindrical portion of the fixed cylinder 1 is cut out to provide an opening. In addition, the shutter unit 7 is used during the photographing operation.
Is opened and the light emitted from the third lens unit 103 leaks out of the fixed barrel 1 and reaches the film surface, and is also suppressed by the groove 1b being closed instead of the opening.

Further, the distance from the optical axis of the inner surface 1e of the groove 1d to the optical axis is determined by the accuracy of manufacturing the parts of the fixed cylinder 1, so that the variation in the dimensional error from the optical axis to the sliding surface of the encoder board 24 is reduced. You. Therefore, the contact pressure of the encoder brush 17 with the encoder board 24 can be stabilized, and the reliability can be increased. In addition, the degree of integration of the variable focal length lens barrel as a unit can be increased, making it easier to check the operation at the unit stage and reducing the man-hour for the final assembly process of the camera incorporating this variable focal length lens barrel. can do. On the other hand, when an opening is provided in the fixed cylinder 1 and the encoder board 24 is fixed to the body side, and the encoder brush 17 is brought into contact with the encoder board 24 through this opening, the body of the fixed cylinder 1 The contact pressure of the encoder brush 17 also tends to fluctuate due to variations in the mounting position on the brush. Also, the signal output from the encoder board 24 cannot be checked before the variable focal length lens barrel is assembled into the body.

Incidentally, the groove 1d is fixed to the fixed cylinder 1 as described above.
Is provided outside the root diameter of the female helicoid screw 1a, so that the cylindrical portion of the fixed cylinder 1 has a large protrusion on the outer peripheral portion. However, the lens barrel installation space on the body side has a rectangular or square shape when the body is viewed from the front. Therefore, a substantially triangular space is formed at the four corners between the lens barrel installation space on the body side and the lens barrel. By locating the groove 1d in this space, an efficient layout becomes possible.
The above effects can be obtained without increasing the size of the camera.

-FPC Guide-Returning to FIG. 8, the FPC guide 16a provided on the body 16 will be described. In the process of retracting the variable focal length lens barrel from the telephoto side to the retracted position, the shutter FPC 7a has rigidity and attempts to resist bending, so that the radius of curvature of the shutter FPC 7a is likely to be large. When the second drive cylinder 3 moves backward in such a state, the shutter FPC 7a is sandwiched between the third lens group 103 and the body 16, and so-called jamming may occur. The FPC guide 16a guides and pushes out the shutter FPC 7a, which is about to expand greatly, in a direction away from the optical axis. The shutter FPC 7a pushed out by the FPC guide 16a fits smoothly into the groove 1d without being sandwiched between the third lens group 103 and the body 16. The FPC guide 16a can suppress an increase in manufacturing cost by being formed integrally with the body 16.

-Third Group Lens Frame-As shown in FIGS. 1 and 6, the third group lens frame 8 is provided with a projection 8b in a direction substantially parallel to the optical axis. The protrusion 8b serves to regulate the opening of the shutter unit 7 according to the focal length of the variable focal length lens as described below.

FIGS. 11A and 11B show a part of a longitudinal section along the optical axis of the variable focal length lens barrel according to the present embodiment, wherein FIG. 11A shows a retracted state, and FIG. And (c) show the situation at the telephoto end. As the variable focal length lens barrel extends from the wide end to the telephoto end, the group spacing between the second group lens 102 and the third group lens 103 becomes as shown in FIG.
(B) Shrink as shown in (c). A step cam 8c is provided at the tip of the projection 8b, and its profile is such that the lift amount is reduced stepwise in the radial direction centering around the optical axis from the root to the tip. The thickness of the step cam 8c (projection 8b) in the direction perpendicular to the plane of FIG. 11, that is, the thickness in the circumferential direction of a circle centered around the optical axis is substantially constant from the root to the tip.

The shutter unit 7 is provided with an opening regulating lever 18 which will be described in detail later.
And the aperture regulating lever 18 at the wide end as shown in FIG.
Away and do not touch as shown. Then, the two start to contact each other in the intermediate focal length range, and the lift amount of the aperture regulating lever 18 changes stepwise according to the focal length. At the telephoto end, the lift amount reaches the maximum as shown in FIG. Become. Further, as shown in FIG. 11A, in order to reduce the total length of the variable focal length lens barrel at the time of collapsing and to make the lens barrel compact, the two lens units 102
The distance between the third lens group 103 and the step cam 8c comes into contact with the opening regulating lever 18. At this time, the relative distance in the optical axis direction between the second group lens 102 and the third group lens 103 is
The second group lens 102 and the third group lens 103 when the variable focal length lens barrel is zoomed from the wide end to the tele end.
Are within a change range of the relative distance in the optical axis direction in the optical axis direction. That is, the second group lenses 102 and 3 described above at the time of collapsing are collapsed.
Since there is no deviation from the change range of the relative distance between the group lens 103 and the optical axis in the optical axis direction, it is possible to prevent interference between the shutter unit 7 and the step cam 8c especially only when retracted. It is not necessary to provide a notch,
The degree of freedom in designing the shutter unit 7 and the variable focal length lens barrel is increased.

FIG. 12 is a partially enlarged view of the shutter unit 7 viewed from the film surface side.
(A) shows the state at the wide end, and (b) shows the state at the telephoto end. The shutter unit 7 has an opening regulating lever 18 having an axis p.
It is attached so that it can rotate around the center. One arm of the torsion spring 19 is hung on the projection 18a of the opening regulating lever 18, and the other arm is hung on the projection 7b fixed to the shutter unit 7, and the opening regulating lever 18 is urged in the counterclockwise direction. Is done. The opening regulating lever 18 is positioned in the rotation direction by a rotation stop 7h fixed to the shutter unit 7. A notch 7d is provided in a part of the outer periphery of the shutter unit 7, and the arm 18c of the opening regulating lever 18 is located in the notch 7d. The arm on the opposite side of the arm 18c of the opening regulating lever 18 is provided with a projection 18b extending on the back side of the drawing, that is, on the subject side.

Inside the shutter unit 7, a sector blade 7e that rotates about the axis q is incorporated. In addition,
The shutter unit 7 includes sector blades 7i that operate opposite to the sector blades 7e on substantially the same plane orthogonal to the optical axis.
(A part of which is shown in FIG. 12A) is also incorporated,
Here, the description and the overall illustration are omitted.

A driving pin 7f is engaged with an elongated hole 7g formed in the sector blade 7e, and the sector blade 7e is opened and closed by the driving pin 7f. The protrusion 18b of the opening regulating lever 18 has a length that reaches a space in which the sector blade 7e opens and closes. Therefore, FIG.
In the state of the wide end shown in (a), even if the drive pin 7g attempts to drive to the side that opens the sector blade 7e, the sector blade 7e abuts on the projection 18b, and the opening of the sector blade 7e is restricted, and the sector blade 7e is not fully opened. That is, the aperture diameter determined by the sector blade 7e is equal to the fixed aperture 7c of the shutter unit 7.
Is smaller than the opening diameter determined by As described above, the maximum opening diameter of the shutter unit 7 is controlled by the opening regulating lever 1.
8 regulated.

When the variable focal length lens barrel is located at the telephoto end, the shutter unit 7 and the third lens group frame 8 are
1 (c), the projection 8b (step cam 8c) enters the notch 7d of the shutter unit 7 as shown in FIG. 12 (b). Then, the arm 18c of the opening regulating lever 18 is pushed by the step cam 8c, the opening regulating lever 18 rotates clockwise, and the projection 18b retracts to the outer peripheral side of the shutter unit 7. In this state, when the drive pin 7g is operated to open the sector blade 7e, the sector blade 7e
Since the sector blade 7e does not come into contact with b, the sector blade 7e is fully opened without restricting the opening. The aperture diameter at this time is defined by the fixed stop 7c.

As described above, the step cam 8c is provided on the third lens group frame 8 so as to extend in a direction substantially parallel to the optical axis, and the lift amount changes in the radial direction centering around the optical axis. In addition, the circumferential thickness of a circle centered around the optical axis of the step cam 8c is substantially constant. Also, since the third group lens frame 8 and the shutter unit 7 move straight in the variable focal length lens barrel,
Both do not make a relative rotational movement about the optical axis. With this configuration, the shutter unit 7 and the step cam 8c can be relatively moved in a direction in which the step cam 8c penetrates into the shutter unit 7, so to speak. The volume can be reduced. That is, the escape of the shutter unit 7 provided corresponding to the movement stroke of the step cam 8c, that is, the area of the notch 7d can be reduced. The above-described thickness dimension of the step cam 8c may be determined so as to have a tapered shape as appropriate in consideration of the strength of the step cam 8c and the mold removability during injection molding.

The effects described above will be further described.
Assuming that the shutter unit 7 is seen through from the optical axis direction, most of the inside of the shutter unit 7 is occupied by the moving space of the sector blades 7c and 7e. For this reason, minimizing escape for avoiding interference with the step cam 8c as described above is advantageous for miniaturization of the shutter unit 7. At this time, the notch 7d is provided to extend in the radial direction, which is also advantageous for reducing the size of the shutter unit 7. In other words, providing the cutout extending in the radial direction as described above on the donut-shaped shutter substrate is necessary to provide the cutout extending in the circumferential direction, as is clear from the description of the related art. This can be performed relatively easily.

In the above, an example in which the step cam 8c is provided on the third lens group frame 8 which is arranged adjacent to the shutter unit 7 and moves relative to the shutter unit 7 in the direction of the optical axis with the zooming operation will be described. However, the present invention is not limited to this example. In short, if there is a member that relatively moves in the optical axis direction with respect to the shutter unit 7 according to the zooming operation, the member can be provided with a step cam. For example, in the variable focal length lens barrel according to the present embodiment, it is possible to provide a step cam in the first group cylinder 4. However, it is desirable that the step cam be provided on a member or the like provided on the film surface side, that is, on the image forming surface side of the shutter unit 7. The reason for this is that a light shielding member such as the bellows 11 and a component such as a lens barrier opening / closing mechanism are often provided on the subject side of the shutter unit 7. If the step cam is provided on a member located on the subject rather than the shutter unit 7, it may be difficult to design the light shielding member and the lens barrier opening / closing mechanism.

In the above, an example has been described in which the aperture diameter is limited according to the focal length set by the variable focal length lens barrel having a built-in lens shutter. However, the present invention is applied to a lens mounted on a single-lens reflex camera, for example. It is also possible. At this time, a variable aperture unit is provided instead of the shutter unit 7. Then, the maximum aperture of the variable aperture unit may be limited by the step cam described above.

-Details of zooming operation and focusing operation-FIG. 13 shows first-group lenses 101 and 2 associated with extension and retraction of the variable focal length lens barrel according to the present embodiment.
FIG. 5 is a diagram for explaining the movement of the group lens 102 and the third group lens 103, and the rotation angle of the first driving cylinder 2 is plotted on the horizontal axis, and the stroke in the optical axis direction is plotted on the vertical axis, and is graphed as described below. Things.

In FIG. 13, the graph shows the first driving cylinder 2 obtained by the relative rotation between the fixed cylinder 1 and the first driving cylinder 2.
3 shows the movement stroke of the camera. The graph shows a relative stroke of the second drive cylinder 3 with respect to the first drive cylinder 2 obtained by the relative rotation of the first drive cylinder 2 and the straight guide cylinder 5. The graph shows the relative stroke of the first group cylinder 4 with respect to the second driving cylinder 3 obtained by the relative rotation of the second driving cylinder 3 and the first group cylinder 4. The graph shows the second rotation of the third lens unit frame 8 obtained by the relative rotation between the second drive cylinder 3 and the straight guide cylinder 5.
3 shows a relative stroke with respect to the driving cylinder 3.

The amounts of movement of the first group lens 101, the second group lens 102, and the third group lens 103 with respect to the film surface are determined by the combinations of the strokes indicated by the graphs 1 to 3 described above. As shown in FIG. 13, the amount of movement of each lens group with respect to the film surface can be obtained by synthesizing the amount of movement of the first group lens 101 with a graph. Similarly, the amount of movement of the second group lens 102 is calculated by combining the graph and the graph to obtain the third group lens 103.
Is obtained by combining a graph, a graph, and a graph.

The first-group lenses 101 to 3 described above
To summarize the movement of the lens group 03, the first group lens 101 and the third group lens 103 are held by the rectilinear guide tube 5 so as to be movable relative to the second group lens 102 in the optical axis direction. It is driven with a stroke indicated by the sum. At this time, the first group lens 101 is driven relative to the rectilinear guide frame 5 by the stroke shown by the graph, and the third group lens 103 is driven by the stroke shown by the graph.

When the variable focal length lens barrel having the above configuration is extended from the retracted position to the wide end, that is, to the position FL1 in FIG. 13, a sharp image of the subject located at infinity at the focal length FL1 is formed on the film surface. Is connected to
As the variable focal length lens barrel is further extended from that position, the state changes to a state in which a sharp image of a subject located at a short distance at the focal length FL1 is formed on the film surface (focus adjustment range D1). When the variable focal length lens barrel is further extended, a sharp image of a subject located at almost infinity at the focal length FL2 is formed on the film surface through the variable power range from the focal length FL1 to FL2. Thereafter, when the variable focal length lens barrel is similarly extended, the variable power operation, that is, the operation of changing the shooting angle of view and the focus adjustment operation are alternately repeated, and the lens is located at a short distance at the tele end focal length FL6. It reaches the point where a sharp image of the subject is formed on the film surface. Note that in FIG. 13, D1 <D2... D5 <D6, that is, the focus adjustment range on the tele side is larger than that on the wide side.
This is because the amount of movement of the image plane with respect to the change of the photographing distance increases as the focal length of the photographing lens increases. The extension amount in each of the focus adjustment ranges D1, D2,..., D6 is controlled by the rotation amount of the motor for driving the variable focal length lens barrel.

By controlling the extension amount or the extension amount of the variable focal length lens barrel according to the embodiment of the present invention as described above, the variable power operation and the focus adjustment operation can be performed by one actuator. . For this reason, the variable focal length lens barrel can be reduced in size and the manufacturing cost can be reduced.

Further, according to the above configuration, the cam groove 2c for driving the rectilinear guide cylinder 5 is provided on the first drive cylinder 2, and the cam groove 3d for driving the third lens group 103 is provided on the second drive cylinder. The cylinder 3 can be separately provided. For this reason, it is possible to suppress an increase in the size of the cam cylinder, particularly, an increase in the dimension in the optical axis direction by providing two types of cam grooves in one cam cylinder, and to shorten the entire length of the variable focal length lens barrel when retracted. be able to. At this time, composite lead screws 3f1-3f for driving the first group cylinder 4 are provided on the inner surface of the second driving cylinder 3.
Cam grooves 3d1 to 3d3 for driving the lens frames 6 and 3
d3 can be provided so as to overlap in the optical axis direction. Therefore, it is possible to independently drive a plurality of lens groups with one driving cylinder without increasing the length of the second driving cylinder 3 in the optical axis direction.

Further, the composite lead screw 3 is attached to the second drive cylinder 3.
By providing f1 to f6, the end surfaces of the first driving cylinder 2, the second driving cylinder 3, and the first cylinder 4 on the subject side are flush with the front surface of the body 16 during collapsing as described below. In addition, a variable focal length lens barrel can be easily designed.

In order to align the position of the first drive barrel 2, the second drive barrel 3, and the first barrel 4 on the subject side with respect to the front surface of the body 16 at the time of collapsing, each of the parts existing between these parts is required. The steps need to be zero. That is, a step δ1 between the front end of the first drive cylinder 2 and the front surface of the body 16 shown below the variable focal length lens barrel at the wide end position shown in FIG.
Step δ2 between tip of driving cylinder 3 to tip of first driving cylinder 2;
It is necessary to set the step δ3 at the tip of the second drive cylinder 3 to zero. Among these steps, the rotation angle of the first drive cylinder 2 necessary for setting the step δ1 to zero is determined. Step δ2
Can be made zero by determining the profile of the cam groove 2c according to the rotation angle of the first drive cylinder 2 described above. However, the movement of the first group cylinder 4 in the optical axis direction with respect to the second drive cylinder 3 is determined not by a cam but by a pair of screws, and the lead thereof has a moving stroke required for the imaging range of the first group lens 101 and a second stroke. It is determined based on the rotation angle of the two-drive cylinder 3. In the lead determined as described above, the step δ
Since 3 cannot be set to zero, in the variable focal length lens barrel according to the present embodiment, as shown in FIG. 5, the helicoid screw formed on the inner surface of the second drive cylinder 3 is a composite lead screw. That is, the first lead screws 3b1 to 3b6 are formed based on the rotation angle of the second drive cylinder 3 from the wide end to the collapsed position and the movement stroke of the first cylinder 4 required to reduce the step δ3 to zero. Is determined.
In this way, by using the composite lead screw, it is possible to give a degree of freedom in setting the movement stroke of each element constituting the variable focal length lens barrel.

In the correspondence between the above-described embodiment of the present invention and the claims, the second group lens frame 6 replaces the second lens group with the first group cylinder 4.
Represents the first lens group, the third lens group 8 represents the third lens group,
The straight guide cylinder 5 projects the moving frame, the cam groove 2c projects the first cam groove, the composite lead screw 3f (3f1-3f6) projects the helicoid screw, and the cam groove 3d (3d1-3d3) projects the second cam groove. The portion 5b and the straight guide hole 5d constitute a straight guide portion, respectively.

[0104]

As described above, according to the first aspect of the present invention, the first lens group, which holds the second lens group and is disposed in front of the second lens group, A moving frame for holding the third lens group disposed behind the second lens group so as to be movable in the optical axis direction is a first frame.
The first drive unit having the cam groove formed on the inner surface thereof moves in the optical axis direction, and the second lens barrel and the third lens unit having the helicoid screw and the second cam groove formed on the inner surface thereof. By moving the group relatively to the second lens group in the optical axis direction, the length of the first driving cylinder and the second driving cylinder in the optical axis direction can be reduced. For this reason, the total length of the variable focal length lens in the optical axis direction when retracted can be shortened, and the thickness of the camera can be reduced. At this time, the first lens group 4 and the third lens group 8 are driven by a helicoid screw and a cam groove formed on the inner surface of one cylinder, respectively. The number of parts can be reduced and the outer diameter of the lens barrel can be reduced as compared with the case where the helicoid screw and the cam groove for driving each are formed in separate cylinders. (2) According to the second aspect of the invention, while the first lens group and the third lens group are allowed to move relative to the moving frame along the optical axis direction, the relative movement along the direction around the optical axis is allowed. By providing a moving frame for a rectilinear guide portion for restricting the movement, that is, by providing a rectilinear guide portion for restricting the movement of a plurality of members in the rotation direction in one lens barrel component, reducing the number of lens barrel components Can be. Therefore, the variable focal length lens barrel can be reduced in size, and the manufacturing cost can be reduced. In addition, since relative movement of the first lens group and the third lens group around the optical axis is regulated based on one component, relative play around the optical axis between the first lens group and the third lens group is restricted. Is reduced, the lens barrel accuracy can be increased, and a decrease in the optical performance of the variable focal length lens can be suppressed. (3) According to the third aspect of the present invention, as the first drive cylinder and the second drive cylinder rotate around the optical axis and advance the moving frame, the scaling operation and the vertex adjustment operation are continuously performed. Zigzag meandering cam groove for alternately performing
And the second cam groove are provided separately for the first driving cylinder and the second driving cylinder. Therefore, as compared with the case where the first and second cam grooves are provided apart from each other in the optical axis direction so as not to intersect with each other, the length of the lens barrel in the retracted state in the optical axis direction can be reduced, and Can be made thinner.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating main components of a variable focal length lens barrel according to an embodiment of the present invention.

FIG. 2 is a diagram showing a longitudinal section along an optical axis of a variable focal length lens barrel according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a state where a cam groove and a guide groove are formed on an inner surface of a first driving cylinder.

FIGS. 4A and 4B are diagrams illustrating a state in which a composite lead screw and a cam groove are formed on an inner surface of a second driving cylinder. FIG.
It is a figure which shows a mode that the inner surface of the drive cylinder was expanded | deployed, (b) is a figure which shows the cross section BB of FIG.4 (a).

5A and 5B are diagrams showing a state where a composite lead screw and a male helicoid screw formed on the inner surface of a second drive cylinder are engaged, and FIG. 5A is a diagram showing the entire inner surface of the second drive cylinder.
(B) is a figure which expands and shows a part of male helicoid screw, and (c) is a figure which expands and shows the vicinity of the bending part of a compound lead screw partially.

FIG. 6 is a view showing a state in which a shutter unit, a second lens frame, an urging spring, a third lens frame, and the like are incorporated into a straight guide cylinder.

FIG. 7 is a longitudinal sectional view showing a state where the variable focal length lens barrel according to the present embodiment is at a wide end.

FIG. 8 is a longitudinal sectional view showing a state where the variable focal length lens barrel according to the embodiment of the present invention is in a retracted position.

9A and 9B are diagrams illustrating the shape of the fixed cylinder, where FIG. 9A is a diagram illustrating a state viewed from the front, and FIG. 9B is a diagram illustrating a cross section BB of FIG. 9A.

FIG. 10 is a longitudinal sectional view showing a state where the variable focal length lens barrel according to the embodiment of the present invention is at the tele end position.

FIGS. 11A and 11B are diagrams illustrating a state where the positional relationship between the step cam and the aperture regulating lever changes in accordance with the zooming operation of the variable focal length lens barrel according to the embodiment of the present invention. FIGS. 7A and 7B are diagrams illustrating a case where the camera is at a position, FIG. 7B is a diagram illustrating a state at a wide end, and FIG.

12A and 12B are diagrams illustrating a state in which the opening of a sector is regulated by an aperture regulating lever, wherein FIG. 12A is a diagram illustrating a case at a wide end, and FIG. 12B is a diagram illustrating a case at a telephoto end. .

FIG. 13 shows a first-group lens and a second-group lens associated with extension and retraction of the variable focal length lens barrel according to the embodiment of the present invention.
FIG. 7 is a diagram illustrating a state in which the movement of the group lens and the third group lens, and the scaling operation and the focus adjustment operation are performed alternately.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed cylinder 1a Female helicoid screw 1b Opening 1d groove 2 First driving cylinder 2a Male helicoid screw 2c Cam groove 2d Guide groove 3 Second driving cylinder 3b1-3b6 First lead screw 3c1-3c6 Second lead screw 3d1-3d3 Cam groove 3f1 3f6 Composite lead screw 4 First group cylinder 4a Male helicoid screw 5 Straight guide cylinder 5b Convex part 5c Follower pin 5d, 5f Straight guide hole 5e Key groove 6 Second group lens frame 6a Guide pin 7 Shutter unit 7a Shutter FPC 7b Neck 7c Middle part 7d Notch 7e, 7f Sector 8 Third group lens frame 8a Follower pin 8b Projection 8c Step cam 9 Urging spring 10 Moving key 14 Guide frame 17 Encoder brush 18 Opening control lever 22 FPC stop 24 Encoder board 101 First group lens 102 Second group lens 103 3 lens

Claims (3)

[Claims] A first lens group disposed on a front side of the second lens group and a third lens group disposed on a rear side of the second lens group. A moving frame that is held movably in the axial direction, a first cam groove is provided on the inner surface of the cylinder, and the moving amount is determined based on a rotation angle around the optical axis and a profile of the first cam groove. A first driving cylinder for driving the frame in the optical axis direction, a helicoid screw having a valley of a first depth on the inner peripheral surface of the cylinder, and a bottomed bottom having a second depth deeper than the first depth. A second cam groove is provided so as to overlap the first group lens with respect to the moving frame in the optical axis direction by a moving amount determined based on a rotation angle around the optical axis and a lead of the helicoid screw. Driving and a rotation angle around the optical axis and a profile of the second cam groove. Variable focal length lens barrel and having a second drive cylinder for relative drive to the optical axis direction the third lens group moving amount determined by to the mobile frame based on the Le. 2. The variable focal length lens barrel according to claim 1, wherein the movable frame is provided with the first lens group and the third lens group relative to the movable frame along the optical axis direction. A variable-focal-length lens barrel, further comprising a straight-moving guide portion for restricting relative movement along a direction around the optical axis while allowing the lens. 3. The variable focal length lens barrel according to claim 1, wherein the first drive barrel and the second drive barrel rotate around the optical axis and extend the moving frame. The first, second, and third lens groups are substantially equal to the first shooting angle of view from a position where a sharp image of a subject located at infinity at a first shooting angle of view is formed on a film surface. After passing through a position at which a sharp image of a subject located at a relatively short distance at an equal angle of view is formed on the film surface, it is located at almost infinity at a second angle of view narrower than the first angle of view. From the position where the sharp image of the subject to be formed is formed on the film surface to the position where the sharp image of the subject located at a relatively short distance from the position where the sharp image of the subject is formed on the film surface is substantially equal to the second shooting angle of view. The variable focal length lens barrel, which is driven continuously up to