JPH10160997A - Initial focusing mechanism for zoom lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an initial focusing mechanism for a zoom lens barrel capable of adjusting the initial position of a photographing lens by making the transmission shaft and the transmission element of a power transmission means attachable/detachable after the lens barrel is assembled, and turning the transmission shaft so that one lens barrel may not be turned but the other lens may be turned in the case of adopting a driving mechanism which transmits the turning of one lens barrel turned by receiving motive power from a driving source to the other lens barrel through the power transmission means so as to turn the lens barrel. SOLUTION: A 1st gear for transmission 8 is linked with a 1st internal gear part 2d formed at the rear end of a 1st driving lens barrel 2 turnably housed in a fixed barrel through an intermediate gear 8a, and the gear 8 and the transmission shaft 9 are made attachable/detachable at an optional angle position. An aperture 5b is formed at the part of a key board 5, which is linked with the moving lens barrel and prevents it from turning, faced to the gear 8, and a bearing cover 11 covering the aperture 5b is attachably/detachably provided on the key board 5. A 2nd gear for transmission meshed with the 2nd internal gear part of the 2nd driving lens barrel is supported by the shaft 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention adjusts the position in the optical axis direction of a lens barrel holding a photographing lens in a zoom lens apparatus, a variable focus apparatus, or the like that can change the focal length of the photographing lens. And a mechanism for adjusting the initial focus of the taking lens.

[0002]

2. Description of the Related Art A zoom lens device and a variable focus device employ a mechanism for changing the focal length of a photographic lens by moving a lens barrel holding the photographic lens in the optical axis direction. In the zoom lens device, when the photographing lens moves forward and backward, each lens group needs to move while maintaining a predetermined optical relationship. For this purpose, it is necessary to make adjustments so that each lens group is at a predetermined position and the focal point at that time is focused at a predetermined position in a state where the taking lens is incorporated in the lens barrel. As a method of adjusting the initial focus of the photographing lens, the moving trajectory of an appropriate number of lens groups is set to E ²
There is a method of registering the data in a PROM or the like and moving the lens group based on the data. However, in this method, the driving mechanism becomes expensive and the cost increases. As another method, there is a method in which the focus position on the short focus side and the focus position on the long focus side are adjusted to the same position, and adjustment is performed by moving the entire lens group to a predetermined position.

In order to reduce the size and increase the magnification of a zoom lens device, a so-called three-lens device having four lens barrels is used.
There is a step-out type. That is, the first is attached to the fixed lens barrel.
A second lens barrel, a first lens barrel, a second lens barrel, a second lens barrel, a movable lens barrel, and a movable lens barrel holding a front lens group; A rear lens group is connected to the driving lens barrel, the first driving lens barrel is connected to the fixed lens barrel, the second driving lens barrel is connected to the first driving lens barrel, and the movable lens barrel is connected to the second driving mirror. Each is configured to advance and retreat with respect to the body in the optical axis direction. As a mechanism for moving the first drive barrel, the second drive barrel, and the movable barrel in the optical axis direction, respectively, a first helicoid formed on the inner peripheral surface of the fixed barrel is used.
Screw the male helicoid formed on the outer peripheral surface of the drive lens barrel,
A male helicoid formed on the outer peripheral surface of the second drive lens barrel is screwed into a female helicoid formed on the inner peripheral surface of the first drive lens barrel, and a movable mirror is formed on the female helicoid formed on the inner peripheral surface of the second drive lens barrel. A male helicoid formed on the outer peripheral surface of the barrel is screwed together with a linear motion member for guiding the moving barrel in the optical axis direction, and the first drive barrel is fixed to the fixed barrel, and the second drive barrel is fixed to the fixed barrel. Are rotated with respect to the first driving lens barrel. The first drive lens barrel and the second drive lens barrel serve as a mechanism for transmitting the power of the motor to the first drive lens barrel and rotating the first drive lens barrel, and transmitting the rotation of the first drive lens barrel to the second drive lens barrel. An inner gear portion is formed on the inner peripheral surface of the driving barrel, and a transmission gear meshing with each of the inner gear portions is provided on the transmission shaft, and the transmission shaft is moved linearly in the optical axis direction together with the first driving barrel. The applicant of the present application has already proposed a structure in which the transmission gear meshed with the inner gear portion of the second drive lens barrel can be moved with respect to the transmission axis in the optical axis direction together with the second drive lens barrel.

[0004]

However, if the above-described structure for moving the lens barrel forward and backward by the drive mechanism is adopted, the first drive is performed when adjusting the initial positions of the photographing lens and the lens barrel when adjusting the initial focus. Rotate the lens barrel
The position of the drive barrel relative to the first drive barrel must be adjusted. However, when the first drive lens barrel is rotated, the position of the second drive lens barrel with respect to the first drive lens barrel changes, and the position of the taking lens also changes. It becomes difficult to converge on the object, and the work of adjusting the initial focus becomes complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an initial focus adjusting mechanism for a zoom lens barrel which can easily perform an initial focus adjusting operation.

[0006]

As a technical means for achieving the above object, an initial focus adjusting mechanism for a zoom lens barrel according to the present invention is provided by relatively rotating a plurality of barrels. A drive mechanism for a zoom lens barrel that moves each lens barrel in the optical axis direction, wherein the drive mechanism transmits rotation of one lens barrel to another lens via power transmission means. The shaft constituting the power transmission means and the transmission element connected to the shaft are detachable at an arbitrary angle position, and after positioning the other lens barrel with respect to the one lens barrel, the transmission element and the shaft are connected. It is characterized by adjusting the initial position of the taking lens connected to the lens barrel by coupling.

When the shaft is rotated, the other lens barrel rotates to advance and retreat in the optical axis direction. Therefore, with the transmission element removed, the other lens barrel moves relative to the one lens barrel. To rotate the shaft to a predetermined position. Since the photographing lens held in connection with the lens barrel is moved in the optical axis direction by the movement of the other lens barrel, the initial position of the photographing lens is determined by adjusting the focal point to a predetermined position. Then, if the transmission element is connected to a shaft at the position and the transmission element is connected to one lens barrel, another lens barrel with respect to the one lens barrel,
That is, the starting position of the movement of the photographing lens is determined, and the initial focus is adjusted.

In the case where the above-described structure is adopted, the lens barrel is disassembled again in a state where the position of the other lens barrel is determined, and the transmission element and the shaft are connected again. It is necessary to perform assembly. Therefore, a driving mechanism for a zoom lens barrel that relatively moves a plurality of lens barrels to advance and retreat each lens barrel in the optical axis direction, wherein rotation of one lens barrel is performed via a power transmission unit. In a drive mechanism for transmitting the power to another lens barrel, a shaft constituting the power transmission means and a transmission element connected to the shaft can be detachably attached at an arbitrary angular position after the lens barrel is assembled. After positioning the lens barrel with respect to the one lens barrel, the transmission element and the shaft are connected to adjust the initial position of the taking lens connected to the lens barrel.

In a state where the position of the other lens barrel is determined by adjusting the initial focus, if the transmission element is coupled to the shaft without disassembling the lens barrel, the adjustment of the initial position of the photographing lens is completed. I do.

[0010] A drive mechanism for a zoom lens barrel, wherein the plurality of barrels are relatively rotated to advance and retreat the respective barrels in the optical axis direction, wherein an inner periphery of one rotating barrel is provided. An inner gear portion is formed on the surface, an inner gear portion is formed on the inner peripheral surface of another lens barrel that rotates with respect to the one lens barrel, and the transmission is engaged with and meshed with each of these inner gear portions. In a driving mechanism having a gear supported on a transmission shaft, a rear transmission gear of the transmission gear is detachably attached to the transmission shaft at an arbitrary angular position after the lens barrel is assembled, and After positioning the lens barrel with respect to the one lens barrel, the transmission gear and the transmission shaft are connected to adjust the initial position of the taking lens connected to the lens barrel.

If a gear is used as the transmission element, a gear portion that meshes with the gear is formed on the lens barrel, and the meshing position between the gear and the gear portion is changed, so that the other lens barrel with respect to one lens barrel is changed. The position can be changed. Therefore,
The transmission shaft is rotated with the transmission gear meshing with the inner gear portion of one lens barrel removed, and the other lens barrel is positioned with respect to one lens barrel to adjust the initial focus of the taking lens.
When the adjustment is completed, a transmission gear connected to one lens barrel may be connected to the transmission shaft. Moreover, since the transmission gear can be coupled to the transmission shaft with the lens barrel assembled, there is no need to disassemble the lens barrel when adjusting the focus.

Further, including a lens barrel drive structure suitable for providing the initial focus adjusting mechanism, a first drive lens barrel connected to the fixed lens barrel by helicoid, and a helicoid link to the first drive lens barrel. A second drive lens barrel for guiding the rear lens group forward and backward, and a movable lens barrel connected to the second drive lens barrel for helicoid communication, the rotation of which is prevented and the front lens group is held, and An inner gear portion is formed on each of the inner peripheral surface of the lens barrel and the inner peripheral surface of the second drive lens barrel, and a drive-side transmission gear is provided on the inner gear portion of the first drive lens barrel, and an inner gear of the second drive lens barrel is provided. The driven transmission gears are meshed with each other, the drive transmission gear and the driven transmission gear are supported on a transmission shaft, and the drive transmission gear is detachable at an arbitrary angle position with respect to the transmission shaft. The transmission gear is freely movable in the axial direction with respect to the transmission shaft. The position of the movable lens barrel to be moved and the position of the second drive lens barrel with respect to the first drive lens barrel are changed to adjust the position of the photographing lens, and after positioning, the drive-side transmission gear is coupled to the transmission shaft. I have.

That is, when the first drive lens barrel rotates with respect to the fixed lens barrel, the first drive lens barrel advances and retreats with respect to the fixed lens barrel, and the second drive lens barrel moves to the first drive lens barrel. The second drive lens barrel advances and retreats with respect to the first drive lens barrel by rotating with respect to the first drive lens barrel, and the movable lens barrel whose rotation is prevented is moved forward and backward by the rotation of the second drive lens barrel. Become. Therefore,
When the transmission shaft is rotated in a state where the drive-side transmission gear is disengaged from the transmission shaft, the second drive lens barrel advances and retreats while rotating with respect to the first drive lens barrel, and the movable lens barrel moves to the second drive mirror. Move forward and backward with respect to the torso. At this time, the front lens group moves forward and backward together with the movable lens barrel, and the rear lens group is guided by the rotation of the second drive lens barrel. Therefore, the initial position can be adjusted by adjusting the positions of the movable lens barrel and the rear group lens with respect to the second drive lens barrel and positioning the second drive lens barrel with respect to the first drive lens barrel. Thereafter, by coupling the drive-side transmission gear to the transmission shaft, the meshing position between the drive-side transmission gear and the inner gear portion of the first drive lens barrel and the positional relationship between the drive-side transmission gear and the transmission shaft are determined. Can be

[0014] Then, the connecting position of the transmission gear and the transmission shaft, which should be detachable at an arbitrary angle position, can be easily changed and easily connected. The cross-sectional shape of the coupling portion which is detachable at an arbitrary angle position is formed in a regular polygon, and the hole of the transmission gear is formed in a shape adapted to the cross-sectional shape.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an initial focus adjusting mechanism for a zoom lens barrel according to the present invention will be specifically described based on a preferred embodiment shown in the drawings.

FIG. 3 is a cross-sectional view of a zoom lens barrel suitable for providing the initial focus adjusting mechanism, taken along a plane including the optical axis S. A camera with a zoom lens apparatus using the zoom lens barrel is shown in FIG. In this case, the rail surface frame 20 is attached to the rear end of the zoom lens barrel while being fixed to a camera body (not shown). A fixed lens barrel 1 is fixed to the camera body.

The fixed lens barrel 1 accommodates a first driving lens barrel 2 and a female helicoid 1b formed on the inner peripheral surface of the fixed lens barrel 1.
And a male helicoid 2a formed on the outer peripheral surface of the first drive lens barrel 2.
Are screwed together. The first driving lens barrel 2 accommodates the second driving lens barrel 3, and is formed on the female helicoid 2 b formed on the inner peripheral surface of the first driving lens barrel 2 and on the outer peripheral surface of the second driving lens barrel 3. The male helicoid 3a is screwed. Further, a movable lens barrel 4 is housed in the second drive lens barrel 3, and a female helicoid 3 b formed on the inner peripheral surface of the second drive lens barrel 3 and a male helicoid formed on the outer peripheral surface of the movable lens barrel 4. 4a
Are screwed together.

At the rear end of the first drive lens barrel 2, a key plate 5 having a tongue piece 5a inserted into a long hole formed in the fixed lens barrel 1 along the direction of the optical axis S is provided. It is fixed. A first linear key 6 having a key portion 6a extending forward is fixed to the key plate 5. That is, the first drive lens barrel 2
The first linear key 6 does not rotate since the tongue piece 5a of the key plate 5 is connected to the fixed lens barrel 1 even if the first linear motion key 6 rotates and moves with respect to the fixed lens barrel 1. The first driving lens barrel 2 moves forward and backward in the direction of the optical axis S. The first
A second linear key 7 connected to the rear end of the second drive lens barrel 3 is connected to the key portion 6a of the linear key 6 so that the second linear key 7
Is prevented, so that the second direct-acting key 7 moves back and forth in the direction of the optical axis S with the second drive lens barrel 3 without turning. The second direct-acting key 7 is linked to the movable lens barrel 4 to prevent the movable lens barrel 4 from rotating.

A drive gear 2c is formed on the outer peripheral surface of the rear end of the first drive lens barrel 2, so that the power of a drive motor (not shown) is transmitted through an appropriate gear train.
A first inner gear 2d is formed on the inner peripheral surface of the rear end of the first drive lens barrel 2, and an intermediate gear 8a meshes with the first inner gear 2d as shown in FIG. Transmitted to this intermediate gear 8a.
The gear 8 meshes. The first direct acting key 6
The rear end of the transmission shaft 9 is rotatably supported, and the transmission first gear 8 is fitted to a portion protruding rearward from the first direct-acting key 6. The transmission shaft 9 is provided so as to extend forward, and a transmission second gear is provided at a front portion so as to be slidable in the axial direction with respect to the transmission shaft 9.
10 is fitted. The transmission second gear 10 is supported at the rear end of the second drive lens barrel 3 and meshes with a second internal gear portion 3c formed on the inner peripheral surface of the rear end of the second drive lens barrel 3. Let me do it.

FIG. 2 is a rear view showing a fitting portion between the first transmission gear 8 and the transmission shaft 9. As shown in the figure, the rear end of the transmission shaft 9 is formed in a regular polygon, and the hole of the first transmission gear 8 that fits with the transmission shaft 9 has the shape of the rear end of the transmission shaft 9. So that they match. That is, the rear end of the transmission shaft 9 and the hole of the transmission first gear 9 are formed in a star shape connecting the vertices of a regular octagon in FIG. The hole of the transmission first gear 8 is formed in a regular hexagon.
Therefore, when the transmission first gear 8 is fitted to the transmission shaft 9,
The transmission shaft 9 and the transmission first gear 8 rotate synchronously, and the transmission first gear 8 can be fitted to the transmission shaft 9 at an arbitrary angular position. The transmission first gear 8 and the transmission shaft 9 need not be regular polygons as in this embodiment as long as they are detachable and can be rotated integrally. The cross section of the rear end and the hole of the transmission first gear 8 may be formed in a substantially D-shape.

As shown in FIG. 1, an opening 5b is formed in a portion of the key plate 5 facing the transmission first gear 8, and a bearing lid 11 is detachably attached to the key plate 5 so as to close the opening 5b. It is provided in. The opening 5b is sized to allow the transmission first gear 8 to pass therethrough. When the bearing cover 11 is fixed to the key plate 5, the bearing cover 11 has an end face of the boss portion of the transmission first gear 8 attached thereto. Can appropriately contact and receive the thrust force of the transmission first gear 8 in the thrust direction.

A cam groove (not shown) is formed on the inner peripheral surface of the second drive lens barrel 3, and a connecting pin 13a planted on the peripheral surface of the lens frame 13 holding the rear group lens 12 is provided. A long hole (not shown) penetrates in a direction parallel to the optical axis S formed in the second direct-acting key 7, and the tip of the connecting pin 13a is inserted into the cam groove. Therefore, the rear group lens 12
Is guided by the cam groove by the rotation of the second drive lens barrel 3 and moves forward and backward. Further, the front lens group 14 is held by the movable lens barrel 4 and moves forward and backward together with the movable lens barrel 4. Therefore, the amount of movement between the rear group lens 12 and the front group lens 14 is different, and the rear group lens 12 and the front group lens 14 move while maintaining a predetermined optical relationship.

The operation of the embodiment of the initial focus adjusting mechanism of the zoom lens barrel according to the present invention having the above configuration will be described together with the zoom operation of the zoom lens barrel.

When a driving motor (not shown) is operated and the driving force is shifted through a suitable gear train and transmitted to the driving gear portion 2c of the first driving lens barrel 2, the first driving lens barrel 2 is fixed. It turns with respect to the lens barrel 1. Since the first drive lens barrel 2 is engaged with the fixed lens barrel 1 by helicoids 1b and 2a, the first drive lens barrel 2 is moved along the optical axis with respect to the fixed lens barrel 1 in accordance with the direction of rotation. It will move in the direction of S. The rotation of the first drive lens barrel 2 is moved from the first inner gear portion 2d to the intermediate gear.
8a, the transmission first gear 8, the transmission shaft 9, and the transmission second gear 10 are transmitted to the second internal gear portion 3c of the second drive lens barrel 3, and the second drive lens barrel 3 It rotates with respect to one drive lens barrel 2.

When the rotation of the first drive lens barrel 2 is transmitted to the second drive lens barrel 3, the first internal gear portion of the first drive lens barrel 2 is used.
Since the transmission first gear 8 is rotated from 2d via the intermediate gear 8a, the rotation direction of the transmission first gear 8 is opposite to the rotation direction of the first drive lens barrel 2. The rotation direction of the second drive lens barrel 3 is the second
Since it is the same as the transmission gear 10, it is the same as the first transmission gear 8 and opposite to the first drive lens barrel 2. That is, there is a relative rotation difference between the first driving lens barrel 2 and the second driving lens barrel 3, and the second driving lens barrel 3 rotates with respect to the first driving lens barrel 2. Will be. Further, the first driving lens barrel 2 and the second
Since the driving lens barrel 3 is engaged with the helicoids 2b and 3a, the rotation of the second driving lens barrel 3 with respect to the first driving lens barrel 2 causes the second driving lens barrel 3 to rotate. Optical axis S
In the direction of.

On the other hand, as the first driving lens barrel 2 advances and retreats, the first linear motion key 6 also advances and retreats in the same direction, and as the second driving lens barrel 3 advances and retracts, the second linear motion key 7 moves. Also move in the same direction. Moreover, since the first direct-acting key 6 is linked to the fixed lens barrel 1, the rotation is prevented, and the rotation of the second direct-acting key 7 is also prevented by engagement with the first direct-acting key 6. ing. Since the movable lens barrel 4 is engaged with the second translation key 7, the rotation of the movable lens barrel 4 is also prevented. Since the movable lens barrel 4 is engaged with the second drive lens barrel 3 by helicoids 3b and 4a, the rotation of the second drive lens barrel 3 causes the movable lens barrel 4 to move in the direction of the optical axis S. become.

Since the front lens group 14 is held by the movable lens barrel 4, it moves forward and backward in the direction of the optical axis S together with the movable lens barrel 4. Further, since the rear lens group 12 is connected to a cam groove (not shown) of the second drive lens barrel 3, the rear lens group 12 is guided by the cam groove by the rotation and advance / retreat of the second drive lens barrel 3, and moves forward and backward in the direction of the optical axis S. Will do. For this reason, the rear group lens 12 and the front group lens 14
Is maintained in a predetermined state, and the magnification is changed.

When adjusting the initial position of the taking lens, the bearing cover 11 is detached from the key plate 5 without the first driving lens barrel 2 being accommodated in the fixed lens barrel 1, and the transmission shaft 9 is transmitted. 1
The gear 8 is removed. When the transmission shaft 9 is rotated in this state, the second transmission gear 10 is rotated, and the second drive lens barrel 3 is rotated with respect to the first drive lens barrel 2 to move forward and backward.
The rotation of the second drive lens barrel 3 causes the movable lens barrel 4 to move forward and backward. Therefore, the position of the rear group lens 12 with respect to the cam groove formed in the second drive lens barrel 3 and the position of the movable lens barrel 4
The position of the male helicoid 4a and the screw position of the female helicoid 3b of the second drive lens barrel 3 are adjusted, and the position of the second drive lens barrel 3 with respect to the first drive lens barrel 2 is adjusted to set the initial position of the taking lens. Make adjustments. After the adjustment of these positions is completed, the transmission first gear 8 is fitted to the transmission shaft 9, and the intermediate gear meshed with the transmission first gear 8 and the first inner gear portion 2 d of the first drive lens barrel 2. 8a, the initial position of the taking lens is determined at a position where the transmission first gear 8 is in mesh with the first internal gear 2d via the intermediate gear 8a.

As shown in this embodiment, if the end of the transmission shaft 9 and the hole of the transmission first gear 8 are formed in a regular polygon, the transmission first gear 8 can be arbitrarily arranged with respect to the transmission shaft 9. And the transmission first gear 8 and the transmission shaft 9 can be integrally rotated.

Then, if the first driving lens barrel 2 in which the taking lens is incorporated is housed in the fixed lens barrel 1, the lens barrel is completed.

[0031]

As described above, according to the initial focus adjusting mechanism for the zoom lens barrel according to the present invention, one lens barrel is rotated by the power from the drive source, and the one lens barrel is rotated. The shaft of the power transmission means for transmitting the motion to another lens barrel and the transmission element are made detachable so that they can be assembled at an arbitrary angle after assembling the lens barrel. By rotating the shaft in the detached state, it is possible to rotate another lens barrel without rotating one lens barrel. Therefore, if the photographing lenses are connected to the other lens barrels, the initial positions of these photographing lenses can be adjusted.
Therefore, there is no need to incorporate a mechanism for adjusting the initial position of the photographing lens into the lens barrel in addition to the drive mechanism for the photographing lens, and the structure can be simplified, and the lens barrel and the lens barrel can be simplified. When the lens barrel is incorporated in a camera, the size of the camera can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an initial focus adjusting mechanism of a zoom lens barrel according to the present invention.

FIG. 2 is a rear view showing a fitting portion between a transmission first gear and a transmission shaft which constitute power transmission means.

FIG. 3 is a cross-sectional view of a zoom lens barrel provided with an initial focus adjusting mechanism according to the present invention, cut along a plane including an optical axis.

[Description of Signs] 1 Fixed lens barrel 1b Female helicoid 2 First drive lens barrel 2a Male helicoid 2b Female helicoid 2c Drive gear unit 2d First internal gear unit 3 Second drive lens barrel 3a Male helicoid 3b Female helicoid 3c Second internal Gear part 4 Moving lens barrel 4a Male helicoid 5 Key plate 6 First direct-acting key 7 Second direct-acting key 8 Transmission first gear (transmission element) 8a Intermediate gear 9 Transmission shaft (shaft) 10 Transmission second gear 11 Bearing cover 12 Rear group lens 13 Lens frame 13a Linking pin 14 Front group lens

Claims (5)

[Claims] A zoom lens barrel drive mechanism for moving a plurality of lens barrels relative to each other in the optical axis direction by rotating the plurality of lens barrels relative to each other, wherein power transmission of rotation of one lens barrel is provided. In a drive mechanism by transmitting to another lens barrel through a means, a shaft constituting the power transmission means and a transmission element connected to the shaft can be detachably attached at any angular position, and the other lens barrel is An initial focus adjusting mechanism for a zoom lens barrel, wherein the initial position of the photographing lens connected to the lens barrel is adjusted by coupling the transmission element and the shaft after positioning with respect to the one lens barrel. . 2. A driving mechanism for a zoom lens barrel, wherein a plurality of lens barrels are relatively rotated to move each lens barrel in the optical axis direction. In a drive mechanism by transmitting to another lens barrel via a means, a shaft constituting the power transmission means and a transmission element connected to the shaft can be detachably attached at an arbitrary angular position after the lens barrel is assembled. A zoom lens, wherein after positioning the other lens barrel with respect to the one lens barrel, the transmission element and the shaft are combined to adjust an initial position of the photographing lens connected to the lens barrel. Initial focus adjustment mechanism for the lens barrel. 3. A drive mechanism for a zoom lens barrel, wherein a plurality of barrels are relatively rotated to move each barrel in the optical axis direction, wherein the inner circumference of one rotating barrel is provided. An inner gear portion is formed on the surface, an inner gear portion is formed on the inner peripheral surface of another lens barrel that rotates with respect to the one lens barrel, and the transmission is engaged with and meshed with each of these inner gear portions. In a drive mechanism having a gear supported on a transmission shaft, a rear transmission gear of the transmission gear is detachably attached to the transmission shaft at an arbitrary angular position after the lens barrel is assembled, After positioning the lens barrel with respect to the one lens barrel, the transmission gear and the transmission shaft are coupled to adjust the initial position of the photographing lens connected to the lens barrel. Initial focus adjustment mechanism. 4. A first drive lens barrel connected to the fixed lens barrel by helicoid; a second drive lens barrel connected to the first drive lens barrel by helicoid to guide the rear lens group forward and backward; and the second drive mirror. A movable lens barrel that is connected to the barrel and has a helicoid, is prevented from rotating, and holds a front lens group; and an inner gear is provided on each of the inner peripheral surface of the first driving lens barrel and the inner peripheral surface of the second driving lens barrel. A drive transmission gear is meshed with an inner gear portion of the first drive lens barrel, and a driven transmission gear is meshed with an inner gear portion of the second drive lens barrel, and the drive transmission gear and the driven transmission gear are meshed with each other. The transmission shaft, the drive-side transmission gear is detachable at an arbitrary angle position with respect to the transmission shaft, the driven-side transmission gear is freely movable in the axial direction with respect to the transmission shaft, The position of the movable barrel with respect to the camera and the position of the second drive barrel with respect to the first drive barrel Adjust the imaging lens position Te, the initial focus adjustment mechanism of the zoom lens barrel, characterized in that for coupling the drive-side transmission gear to the transmission shaft after positioning. 5. A cross section of a coupling portion of the transmission shaft, which is detachably attached to the transmission gear at an arbitrary angle position, is formed in a regular polygonal shape, and a hole of the transmission gear is formed into a shape adapted to the cross sectional shape. 5. An initial focus adjusting mechanism for a zoom lens barrel according to claim 3, wherein said mechanism is formed.