JPH0946116A - Flexible antenna element - Google Patents

Abstract

(57) [Summary] [Structure] The base metal fitting 5 is connected to the antenna element 1 through the coil spring 7, and the antenna element 1 is connected to the base metal fitting 5.
In which the resinous molding coating 2 is layered on the outer peripheral surface up to, the intermediate metal layer 9 having the required flexibility is interposed between the coil spring 7 and the resinous molding coating 2 to form the base metal fitting 5. A ventilation hole 8 is provided along the axial direction. [Effects] A flexible antenna adopting a coil spring to obtain a preferable flexible action can solve molding defects and appearance defects due to sink marks after molding all at once, so that the spring can be retained in the mold. No protrusion of support pins on the upper part of the coil spring, and effective prevention of biasing and bending of the spring to prevent inflow of molding resin material into the coil spring under conditions where the external shape is good, ensuring desirable flexibility. In addition, the molding conditions of the thermoplastic elastomer resin layer and the like can be expanded to facilitate the manufacturing operation and efficiently produce a product of uniform quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible antenna element, and it is intended to provide a product which facilitates forming and manufacturing an antenna element used for an antenna for a vehicle-mounted device, and has an accurate action and durability. It is assumed that.

[0002]

2. Description of the Related Art An antenna for an on-vehicle device is preferably flexible, that is, the antenna is appropriately prevented from being broken even if it is caught by another object, so that the vehicle can easily travel and enter. Even when entering the garage or passing through narrow passages, the antenna may come into contact with walls, objects, or support columns, or under conditions where the antenna may pass through trees and catch on surrounding branches. Breakage of the antenna can be properly prevented, and the running resistance can be reduced even when the vehicle is running at high speed by appropriately bending and tilting the antenna installed on the vehicle body.

Accordingly, various proposals or announcements have been made on the above-mentioned provision of flexibility to the antenna. For example, Japanese Utility Model Publication No. 40-2812 discloses a flexible metal rod in a metal spiral. It has been disclosed that they are fitted and locked when they are pulled out, and Japanese Utility Model Laid-Open No. 55712/1989 proposes providing a coil between conductors.

It is essential to use a coil spring as a member for obtaining flexibility in the above-described flexible antenna element. In the state where the coil spring and the metal fittings are assembled, a resinous molding material is injected into the outer periphery of the coil spring to form a cover. In this case, the air in the coil spring is released as shown in FIG. In order to carry out injection molding while holding the part, a plurality of pins are used to communicate the air inside the coil spring with the outside, and to support the coil spring at the center in the mold.

[0005]

In the conventional flexible antenna element as described above, even if the outer periphery of the resin coating layer is formed by resin coating on the outer periphery of the coil spring, irregularities remain on the outer surface of the resin coating layer. As a result, the air in the coil spring is expanded by the heat generated during molding, which has an adverse effect on the molding layer, and furthermore, shrinkage occurs around the coil spring due to shrinkage of the molding material after molding. There are disadvantages that are not favorable.

[0006] Further, there is a high possibility that the molding material enters between the coil springs, and the flexibility of the coil spring is impaired by the molding material entering between the coil springs. For this reason, in order to remove air in the coil spring that has been thermally expanded during molding, air can be removed even when a pin is formed on the side surface of the coil spring 21 to form a lateral hole for air release, as shown in FIG. In addition, it is difficult to completely deaerate the heat-expanded air, and furthermore, there is a disadvantage that the pin hole 23 remains in the appearance of the bent coating layer 22 and the commercial value is reduced.

In addition, since the coil spring 21 is directly exposed to the fluid pressure of the injected resin, the resin enters the spring and the spring 21 is effectively held in a point-like manner by the pin tip. However, there is a disadvantage that the peripheral surface forming layer 22 is bent undesirably and the antenna is bent when the peripheral surface forming layer 22 is removed from the mold after molding, so that the performance of the obtained product becomes unstable.

To reduce sink marks due to shrinkage of the molding layer after molding, the molding conditions and materials are mainly changed, but other quality deteriorations due to the limited materials, for example, flexibility. The required quality or appearance as expected is not always preferable due to deterioration of the properties. It has been attempted to prevent the molding material from flowing into the coil spring by improving the degree of adhesion of the coil spring and controlling the molding conditions, but cannot completely prevent it.

[0009]

SUMMARY OF THE INVENTION The present invention has been studied to solve the problems in the prior art as described above, succeeded in solving those problems accurately, and preventing a reduction in the commercial value of the antenna element. In addition, it has succeeded in securing a preferable flexible action at the element base, and is as follows.

(1) A base metal fitting is connected to an antenna element via a coil spring, and a resinous material coating is layered on an outer peripheral surface from the antenna element to the base metal fitting. A flexible antenna element, wherein an intermediate layer having a required flexibility is interposed between the cover and the cover, and a vent hole is provided in the base fitting along the axial direction.

(2) A connection fitting inserted between the antenna element and one end of the coil spring and inserted into the inner hole of the coil spring and adapted to insert the antenna element is interposed therebetween. A heat-shrinkable tube having a protrusion inserted into the inner hole of the other end of the spring and a flange for receiving the other end of the coil spring, wherein the intermediate layer reaches the flange of the base metal from the connection metal. The flexible antenna element according to the above mode (1), wherein:

(3) The intermediate layer is formed by a heat-shrinkable tube having a thickness of 0.2 to 1.2 mm, and the resinous molding covering the heat-shrinkable tube portion has a thickness at least in the range of the coil spring. The flexible antenna element according to any one of the above (1) and (2), wherein the flexible antenna element is a thermoplastic elastomer resin layer having a thickness of 1.0 to 5 mm.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a flexible antenna according to an embodiment of the present invention; FIG. As described above, the base end side of the antenna element 1 having the antenna top 11 attached to the distal end is attached to the vehicle body surface or the like via the molded cover 2, the base body 3, and the seat part 4. 2 to 4
Are connected to the base body 3 via a base fitting 5 and a connecting fitting 6 as shown in FIG.

As shown in FIGS. 2 to 4, the base end 10 of the antenna element 1 as described above is connected to a coil spring 7 via a connecting fitting 6, and the coil spring 7 is connected to the base fitting 5. However, in the present invention, the coupling metal 6 is used on the antenna element 1 side to incorporate the coil spring 7 assembled in this manner, and the base end 10 of the antenna element is received in the insertion hole 16a of the coupling metal 6 and the coupling metal An insertion protrusion 16 is formed on the coil spring 6 and inserted into one end of the coil spring 7.

The other end of the coil spring 7 has the insertion portion 14 of the base metal fitting 5 inserted therein, and the base end of the insertion portion 14 has substantially the same diameter as the coil spring 7 inserted. The flange 15 is formed, and the intermediate layer 9 is formed on the peripheral surface of the connection fitting 6 from the flange 15 as described above.
As such an intermediate layer 9, it is preferable to use a relatively soft resin film which shows a softening and melting temperature higher than the melting temperature of the above-mentioned molded coating 2 covered on the outer surface thereof,
A coil spring 7 made of a metal having excellent thermal conductivity is joined to the inside, and furthermore, as described later, the coil spring 7
According to the present invention, the molding coating 2 is applied under the condition that the air inside can be released to the outside, the softening point of the intermediate layer is not limited by the melting point of the molding coating 2, that is, the melting point of the molding coating 2 It was confirmed that the molded coating 2 was appropriately formed under the condition that the softening point of the intermediate layer 9 was considerably low.

As the intermediate layer 9 made of such a resin film, a tape material made of vinyl chloride, ethylene propylene, polyolefin, or the like may be spirally wound, but is preferably a heat-shrinkable material, and is heated after winding. By doing so, it covers from the connection metal fitting 6 to the base metal fitting 5 as shown in FIG. 3 or FIG. A more preferable intermediate layer 9 is a tube made of a heat-shrinkable material such as ethylene propylene or polyolefin as described above. Injection molding and heat treatment of a melt of elastomer such as polyester
A tight connection seal is completed in a state where the flange 15 of the base metal fitting 5 is covered from the base end of the antenna element 1 inserted into the base member 5.

According to the present invention, as described above, the intermediate layer 9 formed as described above is accommodated in the molded cover 2.
It is as shown in the drawing that an engaging projection 13 is appropriately formed on the peripheral surfaces of the connecting metal fitting 6 and the base metal fitting 5 in order to fix the formed coating 2 formed as described above. A connecting portion 12 is formed in the base metal fitting 5 to connect with the base body 3 as shown in FIG. 1, and a vent hole 8 is formed in the axis of the base metal fitting 5. When the molded coating 2 as shown in FIG. 4 is formed, the air that has been heated and expanded in the coil spring 7 is released.

More preferably, the thickness of the intermediate layer 9 is about 0.4 to 0.8 mm for ethylene propylene rubber.
The polyolefin has a thickness of about 0.2 to 0.3 mm, and the molded coating 2 is preferably a heat-flexible resin such as the above-mentioned polyurethane elastomer, and has a thickness of 0.2 at the portion covered with the intermediate layer 9. About 5 to 3 mm is appropriate. In addition, 3 mm is applied to the base metal fitting 5 covering portion of the molded coating 2.
It may be formed as the above thick layer.

A base metal fitting is connected to the antenna element via a coil spring, and a resinous coating is layered on the outer peripheral surface from the antenna element to the base metal fitting. Since the intermediate layer having the required flexibility is interposed therebetween, the resinous molded coating layered on the outer peripheral surface of the intermediate layer enters the coil spring, so that the flexible function of the coil spring is not hindered. Chill out. As the resinous coating, a rubber-like one called an elastomer is suitable in order to secure preferable flexibility for the entire antenna.

Further, by providing the above-mentioned base metal fitting with a ventilation hole extending in the axial direction, the air in the coil spring is appropriately released from the base metal fitting part when the air in the coil spring is thermally expanded during the molding of the resinous resin molding. In addition, it is possible to appropriately prevent adverse effects of the molding coating layer due to the inflated air, and sufficiently prevent sink marks around the coil spring due to thermal contraction after molding.

A connection fitting inserted into the coil spring inner hole and adapted to insert the antenna element is interposed between the antenna element and one end of the coil spring, and a base fitting of the coil spring is provided on the base fitting. A protrusion inserted into the other end inner hole and a flange receiving the other end of the coil spring are provided, and the intermediate layer as described above is a heat-shrinkable tube that reaches from the connection fitting to the flange of the base fitting. In this way, a simple layered connection can be formed by simply attaching the heat-shrinkable tube and subsequently performing the heat-shrink operation.

The intermediate layer is formed by a heat-shrinkable tube having a thickness of at least 0.2 to 1.2 mm in the range of the coil spring, and a resinous molding covering the heat-shrinkable tube portion is provided at least in the coil spring portion. Range of thickness
A thermoplastic elastomer resin layer having a thickness of 1.0 to 5 mm allows the heat shrinking operation as described above to be effectively performed, and the coil spring is held in the center of the heat shrinkable tube portion, and the resin material is in a proper and uniform state. To easily and efficiently manufacture an antenna having strength and durability suitable for transmitting and receiving by mounting a molded coating on the outer surface of a vehicle body while running. The preferred thickness range for the heat-shrinkable tube is 0.4 to 0.8 mm, and the preferred thickness range of the thermoplastic elastomer resin layer is 1.5 to 2.5 mm.

[0023]

According to the present invention as described above, a coil spring is used as a conventional flexible antenna of this kind to obtain a preferable flexibility, and the appearance due to defective molding or sink marks after molding is obtained. In order to resolve defects and other problems at once, without having to protrude support pins etc. in the mold to hold the spring, and to effectively prevent the bias and bending of the spring and improve the appearance of the coil spring The flow of molding resin material into the mold is prevented to ensure favorable flexibility, and the molding conditions such as the thermoplastic elastomer resin layer are expanded to facilitate the production operation and efficiently produce products of uniform quality. It is an invention that has such an effect and is industrially significant.

[Brief description of drawings]

FIG. 1 is a side view showing a general external configuration of a flexible antenna according to the present invention.

FIG. 2 is a partial cross-sectional view showing a cross-sectional structure of the molded covering portion.

FIG. 3 is a partial side view showing a cross section of a connecting fitting and a base fitting shown in FIG. 2;

FIG. 4 is an enlarged cross-sectional view of the molding cover and the inner metal part.

FIG. 5 is a cross-sectional view of a conventional technique in which a molded coating is formed to hold a coil spring at a central portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna element 2 Molding cover 3 Base part 4 Sheet part 5 Base metal fitting 6 Connection metal fitting 7 Coil spring 8 Vent hole 9 Intermediate layer 10 Antenna element base end part 11 Antenna top 12 Connection part 13 Projection part 14 Insertion part 15 Flange part Reference Signs List 16 insertion protrusion 16a insertion hole 17 connection fitting 21 coil spring in prior art 22 formed layer on its peripheral surface 23 pin hole in formed layer 22

Claims (3)

[Claims] 1. A base member connected to an antenna element via a coil spring, and a resinous coating is layered on an outer peripheral surface from the antenna element to the base member. A flexible antenna element, characterized in that an intermediate layer having a required flexibility is interposed between the base member and the base metal fitting, and a ventilation hole is provided along the axial direction. 2. A coupling fitting inserted between said antenna element and one end of said coil spring and inserted into said coil spring inner hole to insert said antenna element therein, said base fitting comprising said coil spring. And a flange portion for receiving the other end of the coil spring and a projection inserted into the inner hole of the other end of the base member, wherein the intermediate layer is a heat-shrinkable tube extending from the connection fitting to the flange portion of the base fitting. Claim 1.
4. The flexible antenna element according to item 1. 3. The intermediate layer is formed of a heat-shrinkable tube having a thickness of 0.2 to 1.2 mm, and the resinous molding covering the heat-shrinkable tube portion has a thickness at least in a range of a coil spring. 3. The flexible antenna element according to claim 1, wherein the flexible antenna element is a thermoplastic elastomer resin layer having a thickness of 1.0 to 5 mm.