JPH05188255A - Fitting structure of zoom lens - Google Patents

Abstract

PURPOSE:To provide the fitting structure of the zoom lens which makes a zoom lens device compact without increasing the deviation quantity of the optical axis of each lens group by coupling the lens frame bodies of a variator lens group and a compensator lens group with two support rods so that guide holes and guide grooves are alternated, arranging the two support rods at 90 deg. to the center axes of the lens groups, and further arranging a side cam cylinder by the frame bodies. CONSTITUTION:The lens frames 14 and 16 of the variator lens group 10 and compensator lens group 12 are coupled with the two support rods 20 and 22 so that the guide holes and guide grooves are alternated. Then the two support rods 20 and 22 are arranged at 90 deg. to the center axes P of the variator lens group 10 and compensator lens group 12 and the side cam cylinder 40 is arranged by the lens frame bodies 14 and 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens mounting structure, and more particularly, to a variator lens group, which is movable among a plurality of lens groups constituting a zoom lens in the optical axis direction with a predetermined relationship during zooming operation. The present invention relates to a mounting structure for a compensator lens group.

[0002]

2. Description of the Related Art Generally, a zoom lens is composed of four groups of a focus lens group, a variator lens group, a compensator lens group and a master lens group. In such a zoom lens, for example, the focus ring is rotated to move the focus lens group in the optical axis direction for focus adjustment, and the zoom cam barrel is rotated to bring the variator lens group and the compensator lens group into a predetermined relationship with each other. By moving the lens in the direction, the focal length does not move and the magnification can be changed.

By the way, as shown in FIG. 5, the variator lens group 1 and the compensator lens group 2 are attached to the lens frame bodies 3 and 4, respectively. Then, the guide holes 6 and 6 formed in the lens frame bodies 3 and 4 so that the optical axes of the variator lens group 1 and the compensator lens group 2 are aligned with each other.
A pair of support rods 8 and 9 are attached to and the steady rest guide grooves 7 and 7 to support the lens frames 3 and 4.

Cam pins 10 and 11 are planted on the lens frames 3 and 4, respectively. This cam pin 10, 11
By inserting the lens frame bodies 3 and 4 into the zoom cam barrel 12, the cam groove 13 formed in the zoom cam barrel 12,
14 is fitted. Therefore, by rotating the zoom cam barrel 12, the lens frame bodies 3 and 4 can be moved back and forth in the optical axis direction in a predetermined relationship.

By the way, the guide hole 6 and the guide groove 7 are provided.
Are formed at the positions shown in FIG. 6 in order to minimize the deviation of the optical axis. That is, the guide hole 6 and the guide groove 7
Are formed on the lens frame bodies 3 and 4 at symmetrical positions with respect to the optical axis P of the lens groups 1 and 2. Accordingly, the displacement amount Δp of the optical axis is expressed by the following equation when the support rod 8 is taken as the center.

Δp = Δx · l1 / l2 (Δx is the amount of backlash of the support rods 8 and 9 in the guide groove 7), and here,
Since l1 / l2≈1 / 2, Δp = Δx · 1/2. In this way, the guide hole 6 and the guide groove 7 are
The mounting position is determined to be 180 ° opposite to each other so that the deviation amount Δp of the optical axis can be reduced as much as possible.

[0007]

However, in the conventional zoom lens mounting structure, the support rods 8 and 9 supporting the respective frame bodies 3 and 4 of the variator lens group 1 and the compensator lens group 2 are placed at 180 ° opposite positions. With this arrangement, there is no problem when the zoom cam barrel 12 is arranged concentrically with the optical axis as shown in FIG. The side cam system arranged in 1 has a drawback that the zoom lens device becomes large in size.

The present invention has been made in view of the above circumstances, and provides a mounting structure of a zoom lens which can make a zoom lens device compact by a side cam system without increasing a deviation amount of an optical axis in a zoom lens group. The purpose is to do.

[0009]

In order to achieve the above object, the present invention provides a first lens frame body to which a first lens group is attached and a second lens frame body to which a second lens group is attached. A lens frame body, a first support rod in which the first lens frame body is guided in the front-rear direction through a guide hole, and a second lens frame body is steady-prevented through a steady-state guide groove, First
The lens frame body of FIG. 3 is precessed through the precession guide groove, and a second support rod for guiding the second lens frame body in the front-rear direction through the guide hole, and the first and second lenses. The first and second cam pins from the first and second lens frame bodies are arranged on the sides of the frame body and are fitted into the cam grooves.
A zoom cam barrel in which the first and second lens frame bodies are moved back and forth in a predetermined relationship in the optical axis direction by being rotated,
In the mounting structure of the zoom lens having, the first and second support rods are arranged so as to be at an angular position of 90 ° with respect to the optical axes of the first and second lens groups,
The zoom cam barrel is arranged between the first and second support rods.

[0010]

According to the present invention, the first and second lens frame members are arranged so that the guide holes and the guide grooves are alternately arranged.
And the first and second support rods,
The first and second lens groups are arranged at an angular position of 90 ° with respect to the optical axis. As a result, the deviation direction of the optical axis centered on the support rod guided by the guide hole is displaced by 90 ° (see FIG. 4).
reference). The amount of deviation Δp of each lens group is

[0011]

[Equation 1], which is larger than the conventional deviation amount. However, since the displacement direction is displaced by 90 °, the maximum combined displacement amount ΔP in the first and second lens groups is

[0012]

[Formula 2] Therefore, the amount of deviation is equivalent to that of the conventional zoom lens mounting structure. Then, the zoom cam barrel is set to the first
And on the side of the second lens frame and between the first support rod and the second support rod. As a result, the zoom lens device can be made compact as compared with the conventional zoom lens device in which the zoom lens is arranged on the side of the lens frame body.

Therefore, according to the present invention, the zoom lens device can be made compact without increasing the deviation amount of the optical axis.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a mounting structure for a zoom lens according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an embodiment in which a variator lens group 10 and a compensator lens group 12 are attached by applying a zoom lens attachment structure according to the present invention.

The variator lens group 10 and the compensator lens group 12 are the lens frame 1 shown in FIGS.
It is attached to 4,16. In addition, a pair of support bars 20,
22 is arranged parallel to the optical axis 18. This support rod 20,
Reference numeral 22 connects and supports the lens frame bodies 14 and 16 in a line so that the optical axes P of the variator lens group 10 and the compensator lens group 12 coincide with each other. That is, the support rod 20 is inserted into the guide hole 24 formed in the lens frame body 14 shown in FIG. 2 to support the lens frame body 14, and the steady rest guide formed in the lens frame body 16 shown in FIG. The lens frame 16 is supported by being sandwiched between the grooves 26. The support bar 22 is sandwiched by the guide grooves 28 formed in the lens frame body 14 shown in FIG. 2 to support the lens frame body 14 and guide holes formed in the lens frame body 16 shown in FIG. The lens frame body 16 is supported by being inserted through 30.

By the way, the guide hole 2 shown in FIGS.
The reference numerals 4 and 30 and the guide grooves 26 and 28 are formed at positions at an angle of 90 ° with respect to the optical axes P of the variator lens group 10 and the compensator lens group 12, respectively.
It is formed in a symmetrical position with respect to. On the other hand, cam pin 3
2 and 34 are the guide holes 2 of the lens frame bodies 14 and 16, respectively.
The protrusions 36 and 38 are formed with the protrusions 4 and 30.
These cam pins 32, 34 have their tip portions 32a, 3
4a is attached to the inside. Also, the cam pin 3
Reference numerals 2 and 34 are fitted into cam grooves 42 and 44 formed on the peripheral surface of the zoom cam barrel 40 shown in FIG. This zoom cam cylinder 40
Is disposed between the support rods 20 and 22, and is rotated, that is, at the time of zooming operation.
4, 16 can move back and forth in the optical axis direction with a predetermined relationship.

Next, the deviation amount of each optical axis P of the variator lens group 10 and the compensator lens group 12 in the mounting structure of the zoom lens constructed as described above will be described. First, the variator lens group 10 will be described with reference to FIG. Support bar 22 in guide groove 28
The deviation S of the optical axis caused by the backlash is
The center of the arrow is the arrow direction shown in FIG. If the amount of backlash is Δx, the amount of deviation Δp of the optical axis P of the variator lens group 10 is

[0018]

[Equation 3] Here, L1 is a length dimension from the support rod 20 to the central axis P of the variator lens group 10, and L2 is a length dimension from the support rod 20 to the support rod 22. Next, in the compensator lens group 12, FIG.
Will be described with reference to.

The deviation direction T of the optical axis caused by the play of the support rod 20 in the guide groove 26 is the direction of the arrow shown in the figure with the support rod 22 as the center. When the amount of backlash is Δx, the amount of deviation Δp of the optical axis P of the compensator lens group 12 is

[0020]

[Equation 4] Next, the two deviation amounts Δp and Δp are combined. As described above, the deviation directions of the variator lens group 10 and the compensator lens group 12 are displaced by 90 ° as shown in FIG. 4, so that the maximum combined displacement amount Δ
P is

[0021]

[Equation 5] Therefore, according to this embodiment, the deviation amount Δp of the variator lens group 10 and the compensator lens group 12 alone is larger than the deviation amount of the conventional zoom lens mounting structure, but the combination thereof is large. The amount of deviation becomes equal.

Further, in the present embodiment, since the zoom cam barrel 40 is arranged between the support rods 20 and 22, the zoom cam barrel 12 is attached to the lens frame bodies 3 and 4 with the conventional zoom lens mounting structure.
The zoom lens device can be made compact as compared with the zoom lens device disposed on the side of the. Further, in this embodiment, since the support rods 20 and 22 are arranged at an angle position of 90 ° with respect to the optical axis, the degree of freedom in designing the side cam for arranging the zoom cam barrel 40 on the side can be increased. That is, since the mutual distance between the cam pins 32 and 34 formed on the lens frame bodies 14 and 16 can be increased, the cam groove 4 of the zoom cam barrel 40 can be formed.
The problem that 2 and 44 interfere with each other can be solved. Moreover, since the support rods 20 and 22 can be configured by two, the manufacturing cost can be reduced.

[0023]

As described above, according to the mounting structure of the zoom lens according to the present invention, the first and second lens frame bodies are arranged so that the guide holes and the guide grooves alternate. And the first and second support rods are arranged at an angular position of 90 ° with respect to the optical axes of the first and second lens groups, and the zoom cam barrel is provided with the first and second support rods. Since they are arranged between the support rods, the zoom lens device can be made compact without increasing the amount of optical axis deviation in the first and second lens groups.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a mounting structure for a zoom lens according to the present invention.

FIG. 2 is a front view showing an embodiment of a variator lens group applied to a zoom lens mounting structure according to the present invention.

FIG. 3 is a front view showing an embodiment of a compensator lens group applied to the mounting structure for a zoom lens according to the present invention.

FIG. 4 is an explanatory diagram showing an amount of deviation of an optical axis caused by mounting play.

FIG. 5 is a perspective view showing an embodiment of a conventional zoom lens mounting structure.

FIG. 6 is a front view showing an embodiment of a variator lens group and a compensator lens group applied to a conventional zoom lens mounting structure.

[Explanation of symbols]

 10 ... Variator lens group 12 ... Compensator lens group 14, 16 ... Lens frame body 18 ... Optical axis 20, 22 ... Support rod 24, 30 ... Guide hole 26, 28 ... Guide groove 32, 34 ... Cam pin 40 ... Zoom cam barrel

Claims (1)

[Claims] 1. A first lens frame body to which a first lens group is attached, a second lens frame body to which a second lens group is attached, and a first lens frame body through a guide hole. And the second lens frame body is guided through the precession guide groove to prevent the precession of the second lens frame body through the precession guide groove, and the first lens frame body is deviated through the precession guide groove. A second support rod that is stopped and guides the second lens frame body in the front-rear direction through the guide hole, and is arranged laterally of the first and second lens frame bodies. Zoom cam barrel in which the first and second cam pins from the lens frame body are fitted into the cam grooves and rotated to move the first and second lens frame bodies back and forth in a predetermined relationship in the optical axis direction. And a zoom lens mounting structure having: The holding bar is arranged at an angle position of 90 ° with respect to the optical axes of the first and second lens groups, and the zoom cam barrel is arranged between the first and second support bars. The mounting structure for the zoom lens.