JPS638030Y2 - - Google Patents

Description

[Detailed description of the invention] The invention consists of coaxially disposing an outer pole group and an inner pole group, each of which is expandable and retractable in multiple stages, insulating the two groups from each other, and providing electrical continuity from the proximal end to the distal end. The present invention relates to a coaxial conductive tube, and more particularly to a coaxial conduit in which the electrical continuity is provided only at the extension limit of the conductive tube.

In general, a coaxial conductive tube has an outer pole group and an inner pole group, each of which is expandable and retractable in multiple stages, electrically insulated from each other and arranged coaxially. It is used as a microphone support pole, or to determine the left-right positional relationship between two devices and to make an electrical connection that can be varied in the axial direction.

Incidentally, this kind of conventional conductive tube has a structure in which, like a rod antenna or the like, the conductive state at both ends is maintained regardless of whether the tube is expanded or contracted, and this causes the following problems.

That is, for example, when a microphone is fixed to the tip of a conductive tube, the base end of the conductive tube is fixed to a VTR camera or 8 mm camera body as a support pole for the microphone. This type of microphone is usually turned on at the same time as the camera starts photographing. By the way, especially with VTR cameras, there is a risk that the operating sound of the electric zoom may be recorded loudly, so it is necessary to extend the conductive tube and move the microphone away from the source of the electric zoom sound to prevent this residual sound from being recorded. There is. However, in reality, users often forget to extend the conductive tube and start recording. In such a case, the operating sound of the electric zoom may be recorded as noise.
Further, when the conductive tube is extended during the photographing process, there is a drawback that the scratching sound during the extension and sliding or the impact sound at the extension limit are recorded as noise.

The present invention was devised to solve these conventional problems, and its purpose is to make the conductive tube conductive only at its extension limit by slightly changing the internal structure of the conductive tube. It is possible to provide coaxial conductive tubes.

The present invention substantially reduces the diameter of the tip inner circumferential surface of at least one of the large diameter poles of both the inner and outer pole groups, and only the reduced diameter portion is attached to the outer circumference of the base end of the small diameter pole of the pole group. A spring is fixedly installed in contact with the poles to make the poles electrically conductive, thereby making the large-diameter pole and the small-diameter pole electrically conductive only at the extension limit of the pole group. Note that the terms "large diameter pole" and "small diameter pole" refer to the relative positional relationship between two poles that are slidably connected to each other, and therefore, the term "large diameter pole" and "small diameter pole" refers to the relative positional relationship between two poles that are slidably connected to each other.
In the case of a group of poles connected in stages or more, this does not necessarily mean the maximum diameter pole and the minimum diameter pole.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 shows a first embodiment of the present invention. The conductive tube 1 according to this embodiment has an outer pole group 2 which is configured to be expandable and retractable in two stages from a large diameter pole 4 and a small diameter pole 5, and an outside pole group 2 which is configured to be expandable and retractable in two stages from a large diameter pole 6 and a small diameter pole 7. It consists of an inner pole group 3.

The large-diameter pole 4 of the outer pole group 2 has a large-diameter portion 4a on the base end side, and a constriction step portion 4 at the tip of the large-diameter portion 4a.
A circular base metal fitting 8 is inserted and fixed into the base end of the large diameter part 4a by caulking or the like, and this base metal fitting A (-) side lug terminal 10 is fixed to the terminal 8 via a fixing member 9. Further, the base end side of a small diameter pole 7 of the inner pole group 3 arranged inside the large diameter pole 4 is arranged to penetrate through the axial center of the base metal fitting 8, and this small diameter pole 7 is interposed between it and the base metal fitting 8. The outer pole group 2 is
It is fixed to the base metal fitting 8 in an electrically insulated state. The base end portion of this small diameter pole 7 protrudes from the end surface of the base metal fitting 8 and constitutes a (+) side lug terminal. Furthermore, an insulating bushing 12 made of a material such as synthetic resin that has low sliding resistance with the small diameter poles 5 of the outer pole group 2, which will be described later, is inserted and fixed at the tip of the narrow diameter portion 4c by caulking or the like. The insulating bush 12 is connected to a spring 14 which will be described later.
It also serves as a stopper.

The small diameter pole 5 of the outer pole group 2 is formed into a cylindrical shape with a slightly smaller diameter than the narrow diameter part 4c of the large diameter pole 4, and the base end of the small diameter pole 5 fitted into the large diameter pole 4 has an inner diameter. Insulating intermediate ring 1 on the circumferential side
3, and a current-carrying spring 14 is attached to the outer peripheral surface. The lower end of the intermediate ring 13 is integrally provided with an outer flange portion 13a that slides within the large diameter portion 4c of the large diameter pole 4 as the small diameter pole 5 expands and contracts. The small-diameter pole 5 comes into contact with the throttle step 4b at the extension limit of the conductive tube 1 to prevent the small-diameter pole 5 from coming off. Further, the spring 14 moves inside the large diameter pole 4 as the small diameter pole 5 expands and contracts, and does not come into contact with the large diameter pole 4 side when the small diameter pole 5 is contracted, as shown by the broken line in the figure. , the small-diameter pole 5 and the large-diameter pole 4 are electrically connected by contacting the inner surface of the small-diameter portion 4c only at the extension limit.

At the upper end of the small diameter pole 5, a cylindrical microphone mounting fitting 15 having a male thread is inserted and fixed by caulking or the like. installed. A lug terminal member 17 on the (+) side is inserted through the axial center of the metal fitting 15, and an insulator 18 made of synthetic resin or the like is interposed between the lug terminal member 17 and the metal fitting 15. 15 and the lug terminal member 17 are integrally connected and fixed in an insulated state. The tip of the large-diameter pole 6 is fitted and fixed to the base end of the lug terminal member 17 by drawing or the like.

The base end of this large diameter pole 6 is folded inward to form a folded part 6a.
a is in contact with a ring-shaped stopper 19 fixedly fixed to the tip of the small diameter pole 7, and the large diameter pole 6
The small diameter pole 7 is prevented from coming off.

In the extended state shown in FIG. 1, the spring 14
is in contact with the inner peripheral surface of the narrow diameter portion 4c of the large diameter pole 4, so the large diameter pole 4 and the small diameter pole are electrically connected, and the large diameter pole 6 constituting the inner pole group 3 and Since the small diameter poles 7 are also electrically connected to each other, the microphone side and the camera side (both not shown) are electrically connected via the conductive tube 1.

On the other hand, when the conductive tube 1 is reduced in size, the spring 14 fixed to the small diameter pole 5 as shown by the broken line in FIG.
moves within the large diameter pole 4 toward its base end side, and is located within the large diameter portion 4a of the large diameter pole 4 without contacting it. As a result, the large-diameter pole 4 and the small-diameter pole 5 constituting the outer pole group 2 are electrically insulated, the closed circuit formed via the conductive tube 1 is opened, and recording by the microphone is stopped. In this case, in the case of a camera having a structure in which photographing and recording are performed simultaneously, it is preferable to configure the circuit so that even if the photographing switch is turned on, the recording operation is not performed.

Therefore, recording is not possible when the conductive tube 1 is in its contracted state, but can be recorded only when it is fully extended, so there is no possibility that the operating sound of the electric zoom or the like will be recorded as noise.

FIG. 2 shows another embodiment of the present invention, in which a large diameter pole 24 is used in place of the large diameter pole 4 in the previous embodiment.

That is, the large-diameter pole 24 has a cylindrical shape with the same diameter at each part without a narrow-diameter part, and inside the tip thereof there is a cylindrical part whose movement in the axial direction is prevented by the caulked part 24a and the insulating bush 12. A conductive material 25 is provided. The spring 14 fixed to the base end of the small diameter pole 5 is in contact with only the conductive material 25 on the large diameter pole 4 side. Note that the other points are completely the same as the structure of the previous embodiment.

Since the large-diameter pole 24 is a straight tube with the same diameter at each location, there is no irregularity on the outer surface, and therefore the external appearance is good and processing is easy.

In the above embodiment, the switch mechanism that turns on and off as the conductive tube 1 expands and contracts is provided in the outer pole group 2, but it may be provided in the inner pole group 3.

The present invention has been explained above based on examples, but
According to the present invention, conduction occurs only at the extension limit of the conductive tube, so there is no drawback as in the conventional method when the conductive tube is used as a microphone support pole. Further, since it is only necessary to substantially reduce the diameter of the inner circumferential surface of the tip end of the large-diameter pole, the structure is simple and cost increase can be suppressed as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of the present invention;
FIG. 2 is a sectional view showing another embodiment of the present invention. 1... Conductive tube, 2... Outer pole group, 3... Inner pole group, 4, 6, 24... Large diameter pole, 5,
7... Small diameter pole, 14... Spring, 25... Conductive material.

Claims (1)

[Scope of utility model registration request] In a coaxial conductive tube in which an outer pole group and an inner pole group, each of which is expandable and retractable in multiple stages, are coaxially arranged and electrically insulated between the two groups, at least one large-diameter pole of the two pole groups is provided. The diameter of the inner circumferential surface of the tip of the pole is substantially reduced, and a spring is fixed to the outer circumference of the base end of the small diameter pole of the group of poles, contacting only the reduced diameter portion and bringing electrical continuity between the two poles. Coaxial conductive tube.