JPH05188254A - Mechanism for adjusting zoom lens - Google Patents

Abstract

PURPOSE:To adjust the positions of respective cam grooves by forming cylindrical side cams which are divided at every cam groove, fitting those cam cylinders in a cam shaft, and rotating the cam cylinders relatively in the circumferential direction so that a focus position in the zooming of a moving lens group reaches a normal focus position. CONSTITUTION:The divided cam cylinders 42 are fitted in the cam shaft 44 and cam cylinders 38 and 40 are fitted in a thin cylinder 46 in order. Cam pins are fitted in the cam grooves 32, 34, and 36 of cam cylinders 38, 40, and 42. Then the positions of the cam grooves 36, 32, and 34 are determined by rotating the cam cylinders 42 relatively to the cam shaft 44 and the cam cylinders 38 and 40 relatively to the thin cylinder 46 in the circumferential direction so that the focus position at the time of the zooming of a 1st lens group, a 2nd lens group, and a 3rd lens group. Then bolts 52 and 54 are screwed in the screw holes 48 and 50 of the cam cylinder 38 and 40 and fixed to the thin cylinder 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens adjusting mechanism, and more particularly to a side-cam type zoom lens in which a rod-shaped cam member for moving the moving lens group at the time of zooming operation is arranged on the side of the moving lens group. Regarding the adjustment mechanism.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, an adjusting mechanism of this type of zoom lens has a pair of lens support rods 1 and 2 arranged in parallel with an optical axis 3 and a pair of lens support rods 1 and 2. 2, the first lens group 4, the second lens group 5, and the third lens group 6, which are moving lens groups, are respectively provided with a lens frame body 7,
It is attached so as to be movable back and forth via 8 and 9. Then, the side cam 10 formed in a rod shape is attached to the lens frame body 7,
The cam pins 11, 12 and 13 formed on the lens frame bodies 7, 8 and 9 are arranged parallel to the optical axis 1 on the side of 8 and 9 in the cam grooves 14, 15 and 16 formed on the side cam 10. Insert it.

Rotatably provided cam shafts 18 and 20 are fixed to both ends of the side cam 10, and a zoom motor 24 is attached to the cam shaft 20 via a gear mechanism 22 composed of a plurality of gears. Be connected. Therefore, when the side cam 10 is rotated by the rotational driving force from the zoom motor 24, the first lens group 4, the second lens group 5 and the third lens group 6 are moved along the cam grooves 14, 15 and 16 with light. Axis 3
It moves back and forth with a certain relationship in the direction. This allows
Zooming is performed by the first lens group 4, the second lens group 5, and the third lens group 6.

Reference numeral 25 is a front lens, and reference numeral 2
Reference numeral 6 is an iris plate, and reference numeral 27 is an iris motor for driving the iris plate 26.

[0005]

However, in the conventional zoom lens adjusting mechanism, when the cam grooves 14, 15 and 16 of the side cam shaft 10 are formed so as to be relatively displaced in the rotational direction due to an error in processing accuracy, Since the groove cannot be corrected, there is a drawback that it is difficult to adjust the position of the cam groove.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adjusting mechanism for a zoom lens in which the position of the cam groove can be easily adjusted.

[0007]

According to the present invention, in order to achieve the above object, a rod-shaped cam member having a plurality of cam grooves is arranged laterally of a plurality of movable lens groups, and In a zoom lens in which each cam follower provided in each moving lens group is fitted in the cam groove, and each moving lens group is moved back and forth in the optical axis direction with a predetermined relationship by rotating the cam member, The rod-shaped cam member is characterized in that a tubular divided cam member divided for each of the cam grooves is fitted into a cam shaft, and the positions of the cam grooves are adjustable in the circumferential direction.

[0008]

According to the present invention, the rod-shaped cam member is divided for each cam groove, the divided divided cam members are formed into a tubular shape, and these divided cam members are fitted into the cam shaft. Then, the divided cam members are relatively rotated in the circumferential direction so that the positions of the respective cam grooves are adjusted so that the focusing position of the movable lens group during zooming becomes the normal focusing position. As a result, the position of the cam groove can be easily adjusted.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A zoom lens adjusting mechanism according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an embodiment of an adjusting mechanism of a zoom lens according to the present invention, and the same or similar members as those in the conventional example shown in FIG.

According to FIG. 1, a pair of lens support rods 1, 2 are provided.
Are arranged parallel to the optical axis 3. The pair of lens support rods 1 and 2 includes a first lens group 4, a second lens group 5, and a third lens group 5.
The lens group 6 is attached so as to be movable back and forth via lens frames 7, 8 and 9, respectively. A rod-shaped side cam 30 to be described later is provided on the side of the lens frame bodies 7, 8, and 9.
Are arranged parallel to the optical axis 3. Three cam grooves 32, 34, 36 are formed in the side cam 30, and the lens frame bodies 7, 8, 9 are formed in these cam grooves 32, 34, 36.
The cam pins 11, 12 and 13 formed in the above are fitted.

The side cam 30 is, as shown in FIG.
It has a cylindrical cam barrel 38, 40, 42 divided for each of the cam grooves 32, 34, 36, and a cam shaft 44 rotatably provided in parallel with the optical axis 3 shown in FIG. There is. A long thin cylinder 46 is provided at the left end of the cam cylinder 42.
It is formed coaxially with. The cam barrel 42 and the thin barrel 46 are
The cam shaft 44 is fitted in the hollow portions 42a and 46a, and is fixed to the cam shaft 44 by a pair of retaining rings 45 and 45 attached to both sides thereof. Further, the cam cylinders 38 and 40 have hollow portions 38a and 40, respectively.
The thin cylinder 46 is fitted in a and is attached coaxially with the cam cylinder 42.

On the other hand, the cam cylinders 38 and 40 are provided with small-diameter stepped portions 39 and 41 at the left end in the figure. The stepped portions 39, 41 are provided with screw holes 48, 50 penetrating the hollow portions 38a, 40a, and bolts 52, 54 are screwed into the screw holes 48, 50 to form bolts 52, 5
The cam cylinders 38 and 40 can be fixed to the thin cylinder 46 at the tip of 4. In addition, the cam barrels 38 and 40 have springs 56.
It is pressed against the cam barrel 42 by the urging force of.

A gear 58 is fixed to the right end of the cam barrel 42 in the figure. This gear 58 is shown in FIG.
The zoom motor 24 is connected via the gear mechanism 22 shown in FIG. Therefore, when the side cam 30 is rotated by the rotational driving force from the zoom motor 24, the first lens group 4,
The second lens group 5 and the third lens group 6 have the cam groove 3
It moves back and forth along 2, 34, 36 in the optical axis 3 direction with a predetermined relationship. Thereby, zooming is performed by the first lens group 4, the second lens group 5, and the third lens group 6.

Reference numeral 25 is a front lens, and reference numeral 2
Reference numeral 6 is an iris plate, and reference numeral 27 is an iris motor for driving the iris plate 26. Next, the focus position adjustment during zooming of the first lens group 4, the second lens group 5, and the third lens group 6 using the zoom lens adjusting mechanism configured as described above will be described.

First, the cam barrel 42 shown in FIG.
4 and then the cam cylinders 38 and 40 are sequentially fitted into the thin cylinder 46 and pressed against the cam cylinder 42 by the spring 56. next,
The cam pins 11, 12, 13 shown in FIG. 1 are fitted into the cam grooves 32, 34, 36 of the cam barrels 38, 40, 42. Next, the cam barrel 42 is attached to the cam shaft 44 and the cam barrel 38 so that the focusing positions of the first lens group 4, the second lens group 5, and the third lens group 6 at the time of zooming become regular focusing positions. , 40 are rotated in the circumferential direction with respect to the thin cylinder 46 to determine the positions of the cam grooves 32, 34, 36. When the positions of the cam grooves 32, 34, 36 are determined, the bolts 5 are inserted in the screw holes 48, 50 of the cam barrels 38, 40.
2, 54 are screwed into the cam cylinders 38, 40 so that the thin cylinders 46
Fixed to. Thereby, the position adjustment of the cam grooves 32, 34, 36 can be easily performed.

When finely adjusting the position of the cam groove 34 with respect to the cam groove 32, the guide of the adjusting jig 64 shown in FIG. 3 is inserted into the pair of holes 60 and 62 formed in the cam barrels 38 and 40. This can be done by inserting the pins 66 and 68 and turning the adjusting jig 64. That is, when the adjusting jig 64 is turned, the cam cylinders 38 and 40 relatively rotate in the circumferential direction by a small amount, so that the position of the cam groove 34 with respect to the cam groove 32 can be finely adjusted.

Further, when finely adjusting the position of the cam groove 36 with respect to the cam groove 34, similarly, the guide pin 66 of the adjusting jig 64 is inserted into the pair of holes 70 and 72 formed in the cam barrels 40 and 42. , 68 can be inserted and rotated. Therefore, in this embodiment, since the side cam 30 is divided into the cam grooves 32, 34, 36, the cam groove 32,
The positions of 34 and 36 can be easily adjusted.

[0018]

As described above, according to the zoom lens adjusting mechanism of the present invention, the rod-shaped cam member is divided into the respective cam grooves, and the divided divided cam members are formed into a cylindrical shape. Since the position of each cam groove can be adjusted in the circumferential direction by fitting the split cam member into the cam shaft, the position of the cam groove can be easily adjusted.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an adjusting mechanism of a zoom lens according to the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of a side cam applied to a zoom lens adjusting mechanism according to the present invention.

FIG. 3 is a perspective view showing an embodiment of a cam adjusting jig applied to a zoom lens adjusting mechanism according to the present invention.

FIG. 4 is a cross-sectional view showing an embodiment of a conventional zoom lens adjusting mechanism.

[Explanation of symbols]

 1, 2 ... Support rod 4 ... First lens group 5 ... Second lens group 6 ... Third lens group 24 ... Zoom motor 30 ... Side cams 32, 34, 36 ... Cam grooves 38, 40, 42 ... Cam barrel 44 ... Cam axis

Claims (1)

[Claims] 1. A rod-shaped cam member having a plurality of cam grooves is arranged laterally of a plurality of moving lens groups, and each cam follower provided in each moving lens group is provided in each of the cam grooves. In a zoom lens in which each moving lens group is moved back and forth in the optical axis direction with a predetermined relationship by fitting and rotating the cam member, the rod-shaped cam member is a cylinder divided for each cam groove. An adjusting mechanism for a zoom lens, characterized in that each of the cam grooves is adjustable in the circumferential direction by being formed by inserting a split cam member into a cam shaft.