Patent Publication Number: US-2011050537-A1

Title: Antenna Formed Inside Film

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an antenna formed inside a film, particularly to an antenna formed inside a film and containing a conductive paste. 
     2. Description of the Related Art 
     The embedded antenna has evolved from a single and narrow band system to a multi and broad band system very rapidly. Some antenna designers have proposed that the cellular phone system (having a frequency band of 850 MHz-2 GHz) should include a penta-band function. The elements of a multiband system should be miniaturized as much as possible. Such a requirement makes the realization of a multiband system more complicated. The consumers have a preference for wireless communication devices with a smooth and neat appearance. Therefore, the appearance, design and integration capability of a multiband antenna become a big challenge. The embedded antenna design also has to consider the following factors: power consumption, efficiency, return loss, and isolation. 
     To conceal an antenna inside a communication device, in recent years a new process has been developed to print the antenna on a plastic film. Firstly, radiation conductors and circuits are stuck to the surface of a plastic casing. Next, a thin film is printed over the radiation conductors and the circuits. Next, an embossing procedure is used to compress the thin film. Next, the semi-product is cut off and then placed inside a mold cavity. Finally, an injection-molding process is used to complete the antenna formed inside a film. The thin film coated on the abovementioned antenna is to enhance the wear resistance and chemical resistance of the radiation conductors. 
     However, when the contact terminals conducting electric signals are inserted into the holes of a plastic housing in the practical fabrication process, they are likely to bump the radiation conductors and the thin film because the assembler operator uses to much force. Thus, the radiation conductors may be damaged and the thin film may bulge, resulting in an antenna malfunction. 
     SUMMARY OF THE INVENTION 
     One objective of the present invention is provide an antenna formed inside a film, which uses a soft conductive paste as the electric connection medium between the radiation conductor and the contact terminal lest the contact terminal directly impact the radiation conductor, whereby the present invention can prevent the radiation conductor and the thin film from being damaged by the impact of the contact terminal. 
     Another objective of the present invention is provide an antenna formed inside a film, which uses a soft metal powder-containing conductive paste as the signal transmission medium between the contact terminal and the radiation conductor, wherein the infinite deformability of the conductive paste can overcome the conventional problem that the elastic fatigue of the contact terminals makes the pins hard to extend or compress, whereby the present invention can lower the frequency of dismounting and replacing components. 
     To achieve the abovementioned objectives, the present invention proposes an antenna formed inside a film, which comprises a thin film, a radiation conductor, a supporter, a conductive paste and at least one contact terminal. The radiation conductor and the circuit are stuck onto the thin film. The supporter is tightly bonded to the radiation conductor by pressing, and at least one trench is formed on the supporter. The contact terminal has a recession, and the recession has a preformed hole. The recession of the contact terminal is inserted into the trench with a spacing existing between the recession and the radiation conductor. The conductive paste is injected into the spacing between the recession and the radiation conductor via the hole. The conductive paste is controlled to have such a thickness that the conductive paste does not overflow from the hole. 
     The present invention is characterized in the soft metal powder-containing conductive paste, which is arranged between the radiation conductor and the contact terminal. Via the soft powder-containing conductive paste, the present invention can prevent the contact terminal from bulging or damaging the radiation conductor and the thin film when the contact terminal is forcefully inserted toward the radiation conductor and the thin film. The soft powder-containing conductive paste not only buffers mechanical impact but also functions as the signal-transmission medium. As the soft powder-containing conductive paste has infinite deformability, it can overcome the elastic fatigue of the contact terminals, which makes the pins hard to extend or compress. Therefore, the present invention can increase the service life of products and lower the frequency of dismounting and replacing components. 
     Below, the embodiments are described in detail to make the technical contents of the present invention easily understood. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view schematically showing an antenna formed inside a film according to a first embodiment of the present invention; 
         FIG. 2  is a perspective exploded view of the antenna formed inside a film according to the first embodiment of the present invention; 
         FIG. 3  is a top-view assembly drawing of the antenna formed inside a film according to the first embodiment of the present invention; and 
         FIG. 4  is a bottom-view assembly drawing of the antenna formed inside a film according to the first embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Refer to  FIG. 1  a sectional view schematically showing an antenna formed inside a film according to a first embodiment of the present invention. The antenna formed inside a film of the present invention comprises a thin film  11 , a radiation conductor  12 , a supporter  13 , a conductive paste  14  and at least one contact terminal  15 . The metallic contact terminal  15  has a recession  151 . 
     The radiation conductor  12  and the circuit are printed on the thin film  11 . The thin film  11  may be a polyester film. The supporter  13  is tightly bonded to the radiation conductor  12  by pressing, and the supporter  13  has at least one trench  131 . The contact terminal  15  is made of a metal sheet, and the recession  151  thereof has a preformed hole  151   a . The recession  151  of the contact terminal  15  is inserted into the trench  131  with a spacing existing between the recession  151  and the patterns of the radiation conductor  12  and the circuits. Via the hole  151   a , the conductive paste  14  is injected into the spacing between the recession  151  and the radiation conductor  12 . In the present invention, the conductive paste  14  may be a gel, and the amount of the injected conductive paste  14  should be controlled to not overflow from the hole  151   a . The thickness of the injected conductive paste  14  is about one-third the depth of the trench  131 . The interface between the supporter  13  and the radiation conductor  12  must be completely sealed up lest the conductive paste  14  flow out. 
     Refer to  FIG. 2  and  FIG. 3  respectively a perspective exploded view and a top-view assembly drawing of the antenna formed inside a film according to the first embodiment of the present invention. The present invention can apply to various wireless communication devices. In the first embodiment of the present invention, the antenna formed inside a film is applied to a mobile phone casing  1 . The sectional view in  FIG. 1  is taken along Line A-A in  FIG. 3 . In the first embodiment, the supporter  13  has two trenches  131 , and the recessions  151  of two contact terminals  15  are respectively inserted into the two trenches  131 . Then, the conductive paste  14  is injected into the spacings via the holes  151   a  to function as the medium of transmitting signals. Thereby, the present invention can implement the mobile phone to transceive signals. 
     In the first embodiment, the thin film  11  of the mobile phone casing  1  has a thickness of about 0.05 mm; the radiation conductor  12  has a thickness of about 0.05 mm; the supporter  13  has a thickness of about 2 mm; the contact terminal  15  is made of a metal sheet and has a total length of about 10 mm, a width of about 1 mm, and a thickness of about 0.05 mm. 
     Refer to  FIG. 1  and  FIG. 4  a bottom-view assembly drawing of the antenna formed inside a film according to the first embodiment of the present invention. After the recessions  151  of the contact terminals  15  have been inserted into the trenches  131  of the supporter  13 , the conductive paste  14  is injected into the spacings between the supporter  13  and the radiation conductor  12  via the holes  151   a  to function as a buffer lest the antenna structure be damaged when the contact terminals  15  are forcefully inserted toward the radiation conductor and the thin film. 
     The above description proves that the present invention possesses utility, novelty and non-obviousness and meets the condition for a patent. However, the embodiments described above are only to exemplify the present invention but not to limit the scope of the present invention. Any equivalent modification or variation according to the spirit of the present invention is to be also included within the scope of the present invention.