Patent Publication Number: US-6340955-B1

Title: Combining method for internal and external insulating sleeves of an antenna on a communication instrument

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to a method for combining the internal and external insulating sleeves of an antenna for a communication instrument, and especially to a method for fast melting combining the internal and external insulating sleeves made of different material on a miniature antenna of a mobile phone in a mass production mode, this makes the combined structure more stable and reliable. 
     2. Description of the Prior Art 
     Conventional mobile phones generally are divided into a fixed and a stretchable type, no matter whichever type they are of, their antennae are destined to have the requirement to be miniaturized following the tendency of miniaturizing of the mobile phones. Particularly a fixed miniature antenna must have its electric coil, contact pieces for a receiving seat etc. densely mounted in the space between the internal and external insulating sleeves, and then the insulating sleeves can be processed for combining. Besides, although a stretchable antenna has structurally a longer stretchable antenna rod, it still has to be processed for combining of the base portion with the coil. 
     FIG. 1 shows a fixed miniature antenna of a mobile phone, it can be combined on the top of the mobile phone in a snap-in mode. Basically, such a fixed miniature antenna of a mobile phone is provided generally in the interior of the external insulating sleeve  10  thereof (namely, the exposed pipe of the antenna) with an internal insulating sleeve  11  for positioning therein a metallic receiving seat  12 . The metallic receiving seat  12  is mounted thereon a coil  15  to cooperate with the inner upper surface  14  of the external insulating sleeve  10 ; while a lower portion  16  thereof can be mounted thereon an exposed elastic contact piece  17 . In the presently used processing mode, the external insulating sleeve  10  having the inner upper surface  14  and a down facing opening  18  is combined with the internal insulating sleeve  11  by applying adhesive  19  therebetween after it is slipped over the internal insulating sleeve  11 . 
     The presently used processing mode of applying adhesive between the internal and external insulating sleeves of a mobile phone has the following disadvantages: 
     1. The mode of applying adhesive often makes people wait for gluing, this results slow production speed, and the amount of adhesive applied and the area of gluing are uncertain, thereby, quality of combining is unstable. 
     2. Applying adhesive for combining at the combining areas of the internal and external insulating sleeves results inferior structural strength; they are no ideal in strength tests. 
     3. The chemical property of such adhesive generally may include corrosiveness; this may damage the whole antenna structure after a long period of use. 
     By virtue that the structural strength of the combining area between the internal and external insulating sleeves effected by the mode of applying adhesive is not as good as desired although it is faster in processing, the methods of processing available presently thereby also include injection enveloping and forming. However, the coil as stated in the above antenna structure must be uprightly held between the external insulating sleeve and the receiving seat. The method of injection enveloping and forming makes the spring coil enveloped and positioned in the interior extremely unstable, this results high rate of inferiority. 
     Another method of fix combining for the internal and external insulating sleeves of such an antenna is to provide a flange and a crevice respectively on the internal and external insulating sleeves to make their integral combination by press engagement. However, the structural strength of the whole antenna completed by such a combining method is still not ideal. And the speed of processing thereof is relatively slow by virtue that the flange must be pressed in the crevice. 
     Further, the internal and external insulating sleeves of the antennae of this kind generally are made of different material, for example, thermoplastic plastics is used for the external insulating sleeve, and polystyrene is used for the internal insulating sleeve. Thermoplastic plastics has a melting point of about 260° C.-270° C., while the melting point of polystyrene is about 190° C.-200° C., thereby, the internal and external insulating sleeves have never been combined by melting in the art. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a method for combining the internal and external insulating sleeves of an antenna for a portable communication instrument. This method can make fast combining of the internal and external insulating sleeves which are slipped one over the other, the structural strength of the whole antenna completed by such a combining method is largely increased. The method of combining renders the processing faster, thereby is especially suitable for mass production, and working hour and cost of production can thus be reduced. 
     To obtain this object, the present invention is arranged to have the internal and the external insulating sleeves molten at their peripheries at the connecting area therebetween, then the internal and the external insulating sleeves are electrically turned on to transiently melt them together at a chosen temperature. The chosen temperature is about the value between the melting points of the two which are made of different material, while the time for the transient melting is within 1 second. 
     The present invention will be apparent in its novelty and other characteristics after reading the detailed description of the preferred embodiment thereof in reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view showing a conventional fixed miniature antenna of a mobile phone; 
     FIG. 2 is a perspective view showing a miniature antenna of the same kind made from the method of the present invention; 
     FIG. 3 is an analytic perspective view showing the internal and the external insulating sleeves and other members of FIG. 2, wherein, the external insulating sleeve is partially shown in sectional view; 
     FIG. 4 is a perspective view showing the external insulating sleeve shown in FIG. 3 is combined; 
     FIG. 5 is a sectional view taken from FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 2,  3 , the fixed miniature antenna of such kind in the present invention also includes an internal insulating sleeve  20  having therein positioning and electric connecting members and capable of combining with an external insulating sleeve  30  to form the whole antenna. After combining, a threaded connecting section  21  on the internal insulating sleeve  20  and an elastic contact piece  40  are partially exposed to the outside ready for connecting the whole antenna to an inner threaded hole of the mobile phone via the threaded connecting section  21 , and the elastic contact piece  40  connects with an internal electric coil  50 . 
     In the specification below, it assumes that the internal and the external insulating sleeve  20 ,  30  are made of different material respectively. Polystyrene is used for the internal insulating sleeve  20 , the melting point of polystyrene is about 190° C.-200° C.; while thermoplastic plastics is used for the external insulating sleeve  30 , its melting point is about 260° C.-270° C. 
     As shown in FIG. 5, an internal through hole  22  of the internal insulating sleeve  20  can be mounted with a metallic receiving seat  23  which can position on an upper surface  24  thereof a coil  50  in cooperation with an inner upper surface  31  of the external insulating sleeve  30 ; while a lower portion  25  thereof can make positioning of the extending-in section of an elastic contact piece  40 , then the internal insulating sleeve  20  can be slipped in an down facing opening  32  of the external insulating sleeve  30 , the two sleeves are in their primary positions ready for melting connection. 
     In the preferred embodiment shown in FIGS. 3 and 4, the internal insulating sleeve  20  has on the shank thereof an outer stepped shoulder  26  which has a very small radial thickness. And the external insulating sleeve  30  has on the inner surface thereof an inner stepped shoulder  33 . When the internal insulating sleeve  20  and the external insulating sleeve  30  are combined with each other by slipping as stated above, the inner stepped shoulder  33  is abutted against the outer stepped shoulder  26  to form a joint for melting. The inner stepped shoulder  33  and the outer stepped shoulder  26  are of small thickness, and are convenient to be connected with each other by heat melting. However, their thickness can be adjusted in pursuance of the connection strength desired. Generally, the total length of the antenna (from the top of the external insulating sleeve  30  to the bottom of the internal insulating sleeve  20  as shown in FIG. 2) is 27 mm, while the length of the external insulating sleeve  30  is 16 mm, its most external diameter is 8.7 mm, and the diameter of the exposed section of the internal insulating sleeve  20  is 5.3 mm; the radial thickness of the inner stepped shoulder  33  and the outer stepped shoulder  26  is 0.15 mm when the internal insulating sleeve  20  and the external insulating sleeve  30  are made of same material, and is the value between 0.15 mm to 0.5 mm when the two sleeves are made of different material. 
     As stated above, when the external insulating sleeve  30  is made of industrial plastic, and the internal insulating sleeve  20  is made of polystyrene, they can be sent into a melting machine such as a super sonic melting machine after the above stated procedure of slipping one over the other, to have the two integrally combined by melting. When the two are made of the mentioned different material, it is found in experiments that the temperature set for melting is the value about the exact middle of the two melting points thereof. That is, if the melting point of industrial plastic is 260° C.-270° C., and if the melting point of polystyrene is 190° C.-200° C., then the set temperature for melting is about 235° C. And electrical turning on for melting must be transient, i.e., the melting operation is completed in about one second. The internal insulating sleeve  20  and the external insulating sleeve  30  are integrally combined with each other by melting at the set temperature for melting and at the joint of the inner stepped shoulder  33  and the outer stepped shoulder  26  under the condition of transient turning on. 
     The internal insulating sleeve  20  and the external insulating sleeve  30  of the present invention are slipped one over the other primarily when the internal insulating sleeve  20  is placed therein the coil  50  and related positioning and electric connecting members, and then can be molten. In this mode, at least the following advantages are provided: 
     1. Assembling of the mobile phone is faster and more convenient, this is suitable especially for mass production. 
     2. The internal insulating sleeve and the external insulating sleeve of the mobile phone are fixedly and integrally combined with each other by melting, the strength of the whole structure is largely increased. 
     3. The whole antenna is more durable without using any chemical adhesive which is corrosive. 
     4. The process of operation is stable and reliable, quality of products can be elevated, and inferiority of products can be lowered. 
     The preferred embodiment cited above is only for illustrating and not for giving any limitation to the scope of the present invention. It will be apparent to those skilled in this art that various modifications or changes can be made to the elements of the present invention without departing from the spirit and scope of this invention. For example, the internal insulating sleeve and the external insulating sleeve can be made of same material, all such modifications and changes also fall within the cope of the appended claims and are intended to form part of this invention.