JPH06337339A - Lens barrel - Google Patents

Abstract

PURPOSE:To reduce cost by means of the reduction of the number of components, to improve space sfficiency and also to miniaturize an entire lens barrel by holding one side of a stop blade in an optical axis directin by a lens holding member. CONSTITUTION:The diaphragm blades 17 and 18 are held between a blade pressing plate 20 and a third lens holding member 3, and the driving arm 21a of a circular arc-shaped diaphragm driving part 21 rocks in a direction shown by an arrow, so that the diaphragm blades 17 and 18 are driven. Guide shafts 3b integrally provided on the third lens holding member 3 are respectively inserted into the round holes 17b and 18b of the diaphragm blades 17 and 18, and the driving arm 21a of the diaphragm driving part 21 passes through the aperture part 3a and is inserted into long holes 17a and 18a. The blade pressing plate 20 is snap-fitted and held by a pawl part 3d, etc., provided on a third lens holding member 3; so that the diaphragm blades 17 and 18 are turned matching with the movement of the driving arm 21a in a direction orthogonally crossing with an optical axis, and a luminous flux can be converged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel used in a video camera or the like, and more particularly to a lens barrel structure having a diaphragm device.

[0002]

2. Description of the Related Art Conventionally, as a lens barrel of this type, a plurality of diaphragm blades, a diaphragm base plate and a blade pressing member arranged so as to sandwich the diaphragm blades, and a diaphragm driving unit are integrated. Generally, a so-called diaphragm unit is used and arranged and fixed in the lens barrel in a form completely independent of the lens barrel.

[0003]

However, in the above-mentioned conventional example, since the unitized diaphragm device is used, the number of parts of the diaphragm device is inevitably increased, the cost is increased, and a large space is required. Had the drawback of becoming larger.

Further, there is a drawback that a deviation between the optical axis and the center of the diaphragm occurs due to the mounting precision of the diaphragm unit, and one of the four corners of the screen becomes dark, or vignetting occurs at worst.

[0005]

According to the present invention, since the lens holding member is used to hold one side of the diaphragm blade in the optical axis direction, the diaphragm base plate and the like, which have been conventionally required, are not required, and the number of parts is reduced. In addition, the lens barrel can be downsized.

Further, since the lens holding member is formed with a rotation support shaft and a guide projection of the diaphragm blade on the surface that holds the diaphragm blade, the opening center of the diaphragm blade and the lens optical axis are highly accurate. Can be adjusted to

Further, by fixing the holding member on the other side of the diaphragm blade and the diaphragm driving section to the lens holding member,
The lens holding member can be made into a diaphragm unit.

Further, since the diaphragm driving section is attached to the lens holding member by snap fitting and the other lens barrel member is provided with a receiving section for preventing the diaphragm driving section from coming off, an impact or the like is prevented. Even if added, the diaphragm drive unit does not come off and reliability can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main sectional view of a lens barrel embodying the present invention, and FIG. 2 is an exploded perspective view thereof.

1 and 2, reference numeral 1 denotes the first lens group I.
And a second lens holding member 2 for holding the second lens group II. A third lens holding member 3 holds the third lens group III. Reference numeral 4 denotes a fourth lens holding member that holds the fourth lens group IV.
The first and third lens groups I and III are fixed lens groups, the second lens group II is a moving lens group that performs a zooming action, and the fourth lens group IV is a moving lens group that performs a focusing action. One end of the second lens holding member 2 is the first lens holding member 1
The other end is held slidably in the optical axis direction by the first guide bars 5 and 6 supported by the third lens holding member 3. The rack member 7 supported by the second lens holding member 2 meshes with the screw screw shaft 8a of the arc-shaped variable power motor 8 fixed to the third lens holding member 3.
The second lens holding member 2 moves in the optical axis direction by the rotation of the screw shaft 8a of the zoom motor. Here, the tip of the screw screw shaft 8a is supported by a bearing 9 provided on the first lens holding member 1.

Reference numeral 10 denotes an opening 1 of the first lens holding member 1.
The cover 1a is provided with an opening 1a so that the screw screw shaft 8a can be visually recognized because it is incorporated in the rack member 7 so as to be meshed therewith. The fourth lens holding member 4 is supported at one end by the third lens holding member 3 and at the other end by the second guide bars 12 and 13 supported by the rear fixed lens barrel 11 having the image pickup device mounting portion 11b. Is movably held.

In FIG. 2, the rack member 14 supported by the fourth lens holding member 4 is a screw screw shaft 1 of an arc-shaped focusing motor 15 fixed to the rear fixed lens barrel 11.
5a, and the fourth lens holding member 4 moves in the optical axis direction by the rotation of the focusing motor. Similar to the screw screw shaft 8a of the variable power motor 8 described above, the tip end of the screw screw shaft 15a is supported by a bearing (not shown) provided in the rear lens barrel 11, and the rear fixed lens barrel 11 for assembling and visual recognition.
The opening (not shown) provided in the cover 16 is covered with the cover 16.

In FIGS. 1 and 2, 17 and 18 are diaphragm blades, and an ND filter 19 (not shown in FIG. 1) is attached to the diaphragm blades 18. The diaphragm blades 17 and 18 are sandwiched between the blade pressing plate 20 and the third lens holding member 3, and the diaphragm blades 17 and 18 are driven by the swinging movement of the driving arm 21a of the arcuate diaphragm driving portion 21 in the direction of the arrow. To be done.
FIG. 3 is a perspective view of an essential part of this diaphragm section.
The guide shafts 3b integrally formed with the third lens holding member 3 are inserted into the round holes 17b and 18b of the aperture holes 17b and 18b, respectively, and the drive arms 21a of the diaphragm drive unit 21 are inserted into the long holes 17a and 18a.
Is inserted through the opening 3a, and the blade pressing plate 20 is snap-fit-held by the claw portion 3d or the like provided on the third lens holding member 3, whereby the drive arm 21a
According to the movement of the diaphragm blade 17 in the direction orthogonal to the optical axis,
It is possible for 18 to rotate and to narrow down the luminous flux.

At this time, the diaphragm blade 1 is provided by the guide rail 3C integrally provided on the third lens holding member 3 and the guide rail 20C integrally provided on the blade pressing plate 20.
It is designed so that 7, 18 can operate smoothly without coming into contact with each other.

Further, in the diaphragm drive section 21, a plurality of claw sections 21e provided on the outer shape section thereof are fitted into a hooking section (not shown) of the third lens holding member 3 provided at the opposing position (snap). It is fixed to the third lens holding member 3 by fitting. Further, as shown in FIG.
1, a convex portion 11a is provided from the rear fixed lens barrel 11 on the opposite side of the fixing surface to the third lens holding member 3, and for example, a claw of the diaphragm driving unit 21 is caused by an impact in the optical axis direction. The rear end of the diaphragm drive unit 21 contacts the convex portion 11a before the portion is completely disengaged from the third lens holding member 3, and the dimensions are set so as to prevent the portion from coming off.

The third lens holding member includes a diaphragm blade 17,
It is possible to take the form of a so-called conventional diaphragm unit by first incorporating the blade 18, the blade pressing plate 20, and the diaphragm driver 21. As shown in FIG. 1, the third lens group is moved from the direction opposite to the diaphragm blade. If the structure is insertable and fixable, it will be easier to handle.

Further, as described above, since the diaphragm blades 17 and 18 are directly incorporated in the holding frame 3, the conventional diaphragm base plate is not necessary, and the space in the thrust direction can be spared accordingly.

Further, the guide shaft 3 of the diaphragm blades 17, 18
Since b is provided integrally with the third lens holding member 3, the deviation between the optical axis and the aperture centers of the aperture blades 17 and 18 can be reduced as compared with the conventional case. Therefore, a great improvement in optical performance can be achieved.

In this embodiment, an arc-shaped motor / driving unit is used in order to make the entire lens barrel compact, but of course a circular actuator can also achieve the same effect. Further, the operation of the diaphragm blade may be not only the swivel type of the embodiment but also the linear movable type.

Further, as a mechanism for preventing the diaphragm drive unit from coming off, FIG.
Then, the convex part is provided with a predetermined clearance,
The convex portion may have elasticity and the diaphragm driving unit may be charged.

[0021]

As described above, according to the lens barrel structure of the present invention, since the diaphragm blade, the blade retainer, and the diaphragm driving unit are incorporated in the lens holding frame, not only the cost reduction due to the reduction of the number of parts but also the space efficiency is achieved. It is also effective for downsizing the entire lens barrel. Further, depending on the assembling procedure, it can be handled independently as a diaphragm unit, and the ease of handling in logistics, which is an advantage of conventional diaphragm units, is not impaired.

Further, since the accuracy of the center of the optical axis and the center of the diaphragm blade is easy to obtain and the misalignment is unlikely to occur, there is no vignetting on the screen.
The brightness at the four corners is almost uniform, and high quality image can be obtained. Furthermore, by eliminating the displacement of the diaphragm drive part and fixing it with the claw part and providing a separate prevention member with a removal prevention mechanism,
It is possible to reduce man-hours and obtain sufficient impact resistance.

[Brief description of drawings]

FIG. 1 is a main sectional view of a lens barrel as an embodiment of the present invention.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a perspective view of a main part of FIG.

[Explanation of symbols]

 3 Third lens holding member 11 Rear fixed lens barrel 11a Convex portion 3b Guide shaft 3c Guide rail 17 Aperture blade 18 Aperture blade 20 Blade holding plate 21 Aperture drive unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Azusa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A lens barrel having a diaphragm device capable of varying the diaphragm amount of a light beam by moving the diaphragm blade in a direction orthogonal to the optical axis, wherein a lens holding member is provided as one holding member for holding the diaphragm blade in the optical axis direction. A lens barrel characterized by using a member. 2. The lens holding member, wherein a surface for holding the diaphragm blade is formed with a rotation support shaft portion of the diaphragm blade and a guide protrusion protruding in the optical axis direction. Lens barrel. 3. The lens holding member is fixed to the lens holding member as a driving unit for driving the diaphragm blade, and the holding member on the other side of the diaphragm blade is also fixed to form the lens holding member as a diaphragm unit. The lens barrel according to claim 1 or 2. 4. The other lens mirror, wherein the drive unit is attached to the surface of the lens holding member opposite to the holding surface of the diaphragm blade by snap fit, and is positioned in a direction of being separated from the lens holding member of the drive unit. 4. The lens barrel according to claim 3, wherein the tubular member is provided with a receiving portion for preventing the drive portion from coming off.