JPS5910078A - Lens barrel for television camera - Google Patents

Abstract

PURPOSE:To realize a compact and lightweight structure as well as a low cost for a lens barrel of a TV camera, by obtaining a material of the lens barrel by compounding a reticular or porous conductive material which is effective in the EMI (electromagnetic wave mixture noise) shielding performance with the synthetic resin. CONSTITUTION:As shown by an upper cross section of a lens barrel, 2, a reticular or porous conductive member 6 is held between synthetic resin materials 5 and 7 and then formed into a barrel form. Then optical system lens groups L1, L2 and L3 are hooked to prescribed stage parts at the inside of the barrel 2 and fixed by a space ring 9 functioning as an intermediate lens holder and detaining rings 8 and 10 functioning as front and back lens holders, respectively. A screw part 11 is carved at the right edge outer circumference of the barrel 2 to be fitted with a fixing ring 12. These rings 8, 9, 10 and 12 have the same structure in which a reticular or porous conductive member is held between synthetic resin materials.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention prevents an unstable video signal, so-called noise phenomenon, which is caused by electromagnetic waves mixing into the electrical system of a photographing device in a television camera (hereinafter referred to as EIMI shield).
oMagnstlc Interferences 5h
The present invention relates to a lens barrel that is capable of yielding.

Conventionally, a lens barrel as shown in FIG. 1 has been known in television cameras. In FIG. 1, reference numeral 1 denotes a television camera body, into which predetermined electrical parts (not shown) including an image pickup tube 3 are installed.
A metal receiver tube 4 with an internal thread is provided in front of the lens barrel 4, and the lens barrel 2 is screwed into the receiver tube 4. Conventionally,
This lens barrel used was made of metal such as aluminum. This type of lens barrel is E
Although it is somewhat satisfactory in terms of MI shielding, it has the following drawbacks.

That is, 1) processing cost is high.

2) There is a limit to how thin the shape can be made, and weight reduction is not possible.

3) Rust occurs.

In order to improve these drawbacks of metal lens barrels, a lens barrel made of synthetic resin mixed with conductive material powder has been proposed, as disclosed in Japanese Utility Model Application Publication No. 57-82308. There is. However, this lens barrel is (a)
Synthetic resins that can be kneaded into conductive materials are limited (polypropylene and polyamide are known). (D)
The EMI shielding effect is low, and in order to achieve an EMI shielding effect that does not cause any practical problems, the wall thickness must be considerably thick (4 to 5 dragons).
Requires. Powders of conductive materials to be mixed include aluminum, carbon, etc., but the cost of turning them into powder and mixing them into the synthetic resin is high.In particular, when metal powder is mixed, injection moldability is reduced. Because it has drawbacks such as.

The present invention achieves a practically acceptable EMI shielding rate,
It is an object of the present invention to provide a lens barrel for a television camera that is lightweight, compact, and inexpensive.

The present invention will be explained below with reference to FIGS. 2 and 3.

FIG. 2 is a cross-sectional view of the top of the lens barrel of the present invention. The lens barrel 2 has a structure in which a net-like or porous conductive member 6 is sandwiched between synthetic resins 5 and 7, and is formed into a cylindrical shape. ing. There is an optical system lens W Ll t L inside the lens barrel.
A restraining ring 8, in which l and l are locked to the step part,
10, and a threaded portion 11 is cut into the outer periphery at the right end in FIG. 2, into which a fixing ring 12 is screwed. and spacing ring8. Deterrent ring 9.1
0 and the fixing ring 12 both have a structure in which a net-like or porous conductive member is sandwiched between synthetic resins. The lens barrel 2 constructed in this manner is screwed onto the television camera body 1 (Fig. 1) using the threaded portion 11, and placed in a predetermined position while adjusting the angle of view by 1°, and the fixing ring 12 is tightened. As a result, the TV camera body IK is fixed.

Figure 3 is a partial cross-sectional view of the lens barrel, synthetic resin 5.
．． A terminal 13 for grounding the net-like or porous conductive member 6 sandwiched between the terminals 1 and 7 is provided at one end of the lens barrel on the television camera body side. The television camera body 1 is grounded and conductive. In addition, when the lens barrel 2 is composed of a large number of parts, a part of the conductive member 6 inside each component is exposed, and the conductive member 6 is placed at the joint of the component parts. By coupling, the entire lens barrel 2 is maintained in a conductive state with the ground of the television camera body 1.

Examples of the conductive member include an aluminum wire, a copper wire, a porous aluminum plate, and a porous copper plate.

In general, synthetic resins have excellent appearance and are preferred as materials for lens barrels for television cameras in terms of mechanical strength and dimensional accuracy, but they are poor in EMI 7-proofing properties. The present invention combines a conductive material that is effective in EMI shielding properties with a synthetic resin in the form of a net-like or porous member to create a material for a television camera lens barrel while taking advantage of the performance of the synthetic resin as described above. This makes it possible to use synthetic resin as a material. According to the present invention, the wall thickness of the lens barrel required to achieve a practically sufficient Ii1MI shielding rate is approximately (9)% compared to that of a lens barrel molded from synthetic resin mixed with conductive material powder. Since it can be made thin, the lens barrel can be made smaller, lighter, and less expensive, and the range of synthetic resins used can be expanded.

The structures shown in Figures 2 and 3 have a structure in which a porous or net-like conductive member is sandwiched between a synthetic tree and a synthetic resin. Since the resins are bonded together, there is no problem of peeling of the bonded parts.

In addition, in order to reduce the weight of the lens barrel, as shown in Figure 4, the lens barrel has a structure in which either the outer tube 14 or the inner tube I5 is made of a conductive material and bonded to a synthetic resin tube. However, this structure has the problem that the adhesive portion is likely to peel off due to temperature changes. In the present invention, the synthetic resin is bonded through the pores of the net-like or porous conductive member, so it does not peel off, has excellent mechanical strength, and can achieve a practically sufficient EMI shielding rate. have an effect.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view of the lens barrel attached to the television camera body. FIG. 2 is a half-sectional side view of the lens barrel. , J3 is a partially cutaway view of the lens barrel. FIG. 4 is a half-sectional side view of the lens barrel. ■...TV camera body 2...Lens barrel 3...
- Image pickup tube 4... Receiving tube 5.7... Synthetic resin 6... Net-like or porous conductive member 8... Third
Lens presser 9...Second lens presser 10...Third
Lens holder 11...Threaded part] 2...Fixing ring 1: Terminal 14 for grounding 3...6...Outer tube 15...Inner tube LI
t L! lL3...Lens agent Yoshimi Kuwahara 407

Claims (4)

[Claims] (1) In a lens barrel for a television camera, which is formed into a cylindrical shape made of synthetic resin, a plurality of lens groups are arranged at predetermined positions on the inside, and can be attached to a receiver tube of a television camera body. A lens barrel for a television camera, characterized in that the barrel has a structure in which a net-like or porous conductive member is sandwiched between synthetic resins. (2) At least one lens holder provided for fixing the lens group in a predetermined position and a fixing ring provided on a threaded portion provided on the outer periphery of one end are made of a net-like or porous conductive member. The lens barrel for a television camera according to claim 1, characterized in that it has a structure sandwiched by resin. (3) The lens barrel for a television camera according to claim 1 or 2, wherein the conductive member is grounded. (4) The lens barrel for a television camera according to claim 3, wherein the ground of the conductive member is electrically connected to the ground of the television camera body.