JPH04310905A - Lens barrel and iris unit used for lens barrel - Google Patents

Abstract

PURPOSE:To reduce the number of parts and an assembling man-hour and to make the whole of a lens barrel small in size, light in weight and inexpensive. CONSTITUTION:In the lens barrel 1A where respective pairs of guide shafts 8, 8, 9 and 9 are disposed in the front and the back lens barrels 3 and 4 constituting the lens barrel 2 in parallel with an optical axis C and a diaphragm blade case 21 which supports first and second lens holders 11 and 13 holding respective lenses 10 and 12 along the respective guide shafts 8 and 9 freely slidably and supports a diaphragm blade 22 so that it freely opens and closes the blade 22 is fixed to the front lens barrel 3 by a screw 25, one end parts 8a and 9a of the respective shafts 8 and 9 are fixed to the front and the back lens barrel 3 and 4 and the other end parts 8b and 9b are fixed to the case 21. Besides, respective hole parts 21b and 21c being as a bearing part which fix the other end parts 8b and 9b of the respective shafts 8 and 9 are formed on the case 21 of an iris unit 20 used for the lens barrel 1A.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner focus type lens barrel used, for example, in a video camera, and an iris unit used in the lens barrel.

0002

2. Description of the Related Art For example, a video camera uses an inner focus type lens barrel in which a master lens group or the like is slightly moved along the optical axis to quickly bring the lens into focus. This will be explained in detail with reference to FIG. 7. Reference numeral 1 indicates a lens barrel used in a video camera. The lens barrel 2 of this lens barrel 1 includes a cylindrical front lens barrel 3 and a cylindrical rear lens barrel 4 connected to the rear of the front lens barrel 3 via screws 5.
It consists of A focusing lens 6 as a front lens group is fitted onto the inner peripheral surface of the front lens barrel 3 on the front side of the flange 3a. In addition, the front flange 4 of the rear lens barrel 4 is
A compensator lens 7 is fitted onto the inner peripheral surface of a. Furthermore, a pair of recesses 3c, 3c are formed on the upper and lower sides of the middle flange 3b of the front barrel 3, and an annular support plate 19 is fixed to the rear edge of the front barrel 3 with screws 18. A pair of guide shafts 8, 8 are interposed between the pair of recesses 19a, 19a so as to be parallel to the optical axis C. recesses 4c, 4
A pair of guides are provided parallel to the optical axis C between C and a pair of recesses 16a, 16a formed in an annular support plate 16 fixed to the rear edge of the rear lens barrel 4 with screws 15. Axis 9,9
There is an intervention.

A pair of guide shafts 8 of the front lens barrel 3
, 8 have a substantially cylindrical first lens holder 11 holding a zoom variator lens 10 fitted therethrough and slidably supported therein, and a pair of guide shafts 9, 8 of the rear barrel 4. A substantially cylindrical second lens holder 13 holding a master lens 12 for focusing is fitted into the lens 9 and is slidably supported therein. Each of these lens holders 1
Bearing holes 11a and 13a through which the guide shafts 8 and 9 pass are formed at the upper ends of 1 and 13, respectively, and approximately U-shaped grooves 11b and 13b are formed at their lower ends.
By forming each lens holder 11,
13 rotation is regulated. Also, these first and second
The lens holders 11 and 13 are moved in the front and rear directions along the optical axis C by driving means such as linear motors (not shown).

Furthermore, between the front lens barrel 3 and the rear lens barrel 4, there is a
An iris unit 20 is interposed. The iris unit 20 includes an aperture blade case 21 having an aperture opening 21a, and a unit that is housed in the aperture blade case 21 and adjusts the amount of light entering the lens barrel 2 by opening and closing the aperture opening 21a. Aperture blades 22 (or two)
and a motor (drive means) 23 which is fixed to the lower end side of the aperture blade case 21 and rotates the aperture blade 22 via a rotating shaft 23a, and the motor (drive means) 23 is fixed to the lower end side of the aperture blade case 21 and rotates the aperture blade 22 via a rotating shaft 23a. It is fixed to the rear edge protrusion of No. 3 with screws 25.

[0005]

[Problems to be Solved by the Invention] However, the conventional lens barrel 1 requires support plates 19, 16, etc. for fixing the rear ends of each guide shaft 8, 9, which makes the number of parts and assembly difficult. The number of man-hours increased, and it was not possible to sufficiently reduce the size, weight, and cost. SUMMARY OF THE INVENTION Accordingly, the present invention provides a lens barrel and an iris unit used in the lens barrel, which can be sufficiently reduced in size, weight, and cost by reducing the number of parts and assembly man-hours.

[0006]

[Means for solving the problem] A guide shaft is disposed in the lens barrel parallel to the optical axis, and a lens holder that holds the lens is slidably supported along the guide shaft, while the lens holder is slidably supported on the lens barrel. In a lens barrel equipped with an aperture blade case supporting the aperture blades so as to be movable to open and close, one end of the guide shaft is fixed to the lens barrel, and the other end is fixed to the aperture blade case. be.

The iris unit used in the lens barrel includes an aperture blade case having an aperture opening, an aperture blade housed in the aperture blade case that opens and closes the aperture opening, and an aperture blade that opens and closes the aperture blade. The aperture blade case is provided with a bearing portion that supports the guide shaft.

[0008]

[Operation] Since the other end of the guide shaft is directly fixed to the bearing of the aperture blade case, the number of parts is reduced and the structure of the lens barrel is simplified. As a result, the entire lens barrel can be made smaller and lighter, and the number of assembly steps can be reduced, leading to lower costs.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Incidentally, the same parts as those in the conventional configuration are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 1, 1A is a lens barrel used for a video camera, and a lens barrel 2 is divided into a front lens barrel 3 and a rear lens barrel 4.
A first variator lens 10 for zooming is held in the front lens barrel 3 via a pair of guide shafts 8, 8.
The lens holder 11 is made slidable, and the second lens holder 13 that holds the master lens 12 for focusing via a pair of guide shafts 9, 9 is made slidable on the rear lens barrel 4. The structure is similar to the conventional structure in that the iris unit 20 is interposed between the front lens barrel 3 and the rear lens barrel 4. Here, as shown in FIG. 2, a pair of concave holes are formed on the front surface of the aperture blade case 21 of the iris unit 20 at positions facing each rear end (other end) 8b of the pair of guide shafts 8, 8. A pair of concave portions (bearing portions) 21b, 21b are formed on the rear surface of the aperture blade case 21 at positions facing each front end portion (other end portion) 9b of the pair of guide shafts 9, 9. Holes (bearing parts) 21c, 21c are formed. The inner flange 3b of the front lens barrel 3 is inserted into the pair of holes 21b, 21b on the front surface of the aperture blade case 21.
The rear end portions 8b of a pair of guide shafts 8, 8 are fixed by press fitting into a pair of recesses (bearing portions) 3c, 3c with respective front end portions (one end portion) 8a fixed by press fitting, and the blade case. A pair of recesses (bearing portions) 4c, 4c of the rear flange portion 4b of the rear lens barrel 4 are inserted into a pair of holes 21c, 21c on the rear surface of the rear lens barrel 21.
The front end portions 9b of a pair of guide shafts 9, 9, each having a rear end portion (one end portion) 9a fixed thereon by press fitting, are fixed by press fitting.

According to the embodiment described above, each of the rear end portions 8b of the pair of guide shafts 8, 8 whose respective front end portions 8a are fixed to the pair of recesses 3c, 3c of the middle flange portion 3b of the front lens barrel 3, A pair of holes 21 in the front of the aperture blade case 20 of the iris unit 20
b, 21b, and the rear flange 4 of the rear lens barrel 4.
The front end portions 9b of the pair of guide shafts 9, 9 whose rear end portions 9a are fixed in the pair of recesses 4c, 4c of b are directly fixed to the pair of holes 21c, 21c on the rear surface of the aperture blade case 20. As a result, the conventional support plate and screws for fixing the support plate to the lens barrel are no longer necessary, the number of parts can be significantly reduced, and the structure of the lens barrel 2 can be simplified. . Thereby, the number of assembly steps can be significantly reduced, and the entire lens barrel 1A can be further reduced in size, weight, and cost.

[0012] Further, as a bearing part, each end part 8b, 9b of each pair of guide shafts 8, 8, 9, 9 is fixed by press fitting to the aperture blade case 21 of the iris unit 20 used in this lens barrel 1A. It is only necessary to form the holes 21b and 21c, respectively, and the ends 8b and 9b of the guide shafts 8 and 9 can be easily attached to the aperture blade case 21 by press fitting, and the lens barrel 1A can be easily attached to the aperture blade case 21. Can be easily assembled in a short time.

FIG. 3 shows a lens barrel 1B of another embodiment. This lens barrel 1B is of a four-group lens system, and a compensator lens 7 is provided at the rear of the inner peripheral surface of the aperture opening 21a of the aperture blade case 20 of the iris unit 20.
is fitted. The structure is the same as that of the previous embodiment, except that a support plate 16 is fixed to the rear edge of the rear lens barrel 4 with screws 15 for fixing the rear end portions 9a of the pair of guide shafts 9, 9 by press fitting. and has substantially the same action and effect.

FIG. 4 shows another embodiment of the lens barrel 1C. This lens barrel 1C is also of a four-group lens system, and the structure of the rear lens barrel 4 is approximately the same as that of the conventional one, with only the rear end portions 8b of the pair of guide shafts 8, 8 of the front lens barrel 3 being , are fixed by press fitting into a pair of holes 21b, 21b formed on the front surface of the aperture blade case 21 of the iris unit 20. Thereby, the number of parts on the front lens barrel 3 side can be reduced, making it possible to reduce the size, weight, and cost.

FIG. 5 shows a lens barrel 1D of yet another embodiment. A pair of penetrating holes (bearing parts) 21d, 21d are formed in the upper and lower parts of the aperture blade case 20 of the iris unit 20 shown in FIG. 6 used in this lens barrel 1D, and a pair of guide shafts 8, 8 is extended from the front lens barrel 3 to the rear lens barrel 4 for common use, further reducing the number of parts.

In another embodiment shown in FIG. 3, a flange is integrally formed on the rear edge of the rear lens barrel 3, as in the embodiment shown in FIG. 1, so that the support plate and screws are omitted. You can.

[0017]

As described above, according to the lens barrel of the present invention, one end of the guide shaft that slidably supports the lens holder that holds the lens is fixed to the lens barrel, and
Since the other end side is fixed to the aperture blade case, there is no need for a conventional support plate or screws for fixing the support plate to the lens barrel, reducing the number of parts and assembly man-hours. The overall size, weight, and cost can be reduced. In addition, since the aperture blade case of the iris unit used in this lens barrel is provided with a bearing portion that fixes one end of the guide shaft, the guide shaft can be easily attached to the aperture blade case of the iris unit. A lens barrel can be easily assembled in a short time.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a lens barrel according to an embodiment of the invention.

FIG. 2 is a side view showing a part of the iris unit used in the lens barrel in cross section.

FIG. 3 is a sectional view showing a lens barrel according to another embodiment of the invention.

FIG. 4 is a sectional view showing a lens barrel according to another embodiment of the invention.

FIG. 5 is a sectional view showing a lens barrel according to still another embodiment of the invention.

FIG. 6 is a side view showing, in cross section, a part of the iris unit used in the lens barrel of still another embodiment.

FIG. 7 is a sectional view showing a conventional lens barrel.

[Explanation of symbols]

1A, 1B, 1C, 1D... Lens barrel, 2... Lens barrel, 8,
9... Guide shaft, 8a, 9a... One end, 8b, 9b... Other end, 10, 12... Lens, 11, 13... Lens holder, 20... Iris unit, 21... Aperture blade case, 2
1a...Aperture opening, 21b...Hole (bearing part), 21c
...Hole (bearing part), 22...Aperture blade, 23...Motor (
drive means).

Claims (2)

[Claims] Claim 1: A guide shaft is disposed in the lens barrel parallel to the optical axis, and a lens holder for holding the lens is slidably supported along the guide shaft, and an aperture blade is attached to the lens barrel. The lens barrel is equipped with an aperture blade case that is movably supported to open and close, and is characterized in that one end of the guide shaft is fixed to the lens barrel, and the other end is fixed to the aperture blade case. lens barrel. 2. An aperture blade case having an aperture opening, an aperture blade housed in the aperture blade case to open and close the aperture opening, and a driving means for opening and closing the aperture blade. 2. The iris unit for a lens barrel according to claim 1, wherein the blade case is provided with a bearing portion for supporting the guide shaft.