Patent Publication Number: US-6215984-B1

Title: Luminous antenna and radiocommunication equipment comprising such an antenna

Description:
FIELD OF THE INVENTION 
     The present invention relates to an antenna intended for a radiocommunication transmitter/receiver, having the appearance of a pin, comprising a light source situated outside the antenna and comprising a light pipe with a light-diffusing part. 
     The invention also relates to a radiocommunication transmitter/receiver having an antenna. 
     The invention applies, for example, to cellular telephones. 
     BACKGROUND OF THE INVENTION 
     An antenna having a light source is described in U.S. Pat. No. 2,473,981 (Wood). The antenna described by this document comprises a light bulb which diffuses light in a transparent sleeve which surrounds the metallic electric conductor which forms the antenna itself. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to improve both the efficiency of the antenna, its reliability and its cost. 
     For this purpose, the antenna itself comprises a helical electric part formed by a metallic spring and at least partly surrounds the light pipe. 
     This permits to transmit light through the electric part of the antenna, without the latter blacking out the light. 
     In a particular embodiment, the light source produces light in the form of flashes. 
     Advantageously, the light pipe and the light-diffusing part are made into one, the light-diffusing part being formed by a treatment which renders the surface light-diffusing and which is applied to a part of the surface of the light pipe. 
     Preferably, the light-diffusing part is situated near to an end of the pin. The light signal is more visible in this way. 
     In a particular embodiment, the light-diffusing surface is surrounded by an envelope of translucent material. 
     The light pipe is advantageously formed by a bundle of flexible optical fibers. 
     In the case of a retractable antenna, this permits of making a loop with the fiber outside the antenna so that the loop is enabled to follow the movement of the antenna. 
     A radiocommunication transmitter/receiver advantageously includes an antenna according to the invention. 
     In a particular embodiment in which the transmitter/receiver is suitable for receiving a call, the transmitter/receiver comprises means for activating the light source when such a call is detected. 
     In another particular embodiment in which the transmitter/receiver has control keys, it comprises means for activating the light source when any key is pressed by a user. 
    
    
     These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 represents a radiocommunication transmitter/receiver having an antenna, 
     FIG. 2A shows a perspective view of an assembled antenna according to the invention, 
     FIG. 2B shows an exploded view of the same antenna shown in FIG. 2A, 
     FIG. 3 represents a cross-sectional view of the antenna of FIGS. 2A-2B, 
     FIG. 4 represents a part of FIG. 3 on a larger scale, and 
     FIG. 5 is a general circuit diagram of a portable telephone. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The radiocommunication transmitter/receiver represented in FIG. 1, which is here a portable telephone, comprises a main body  4  with a keyboard  3  and a screen  2  and, for receiving (or transmitting) radio waves from (to) a transmitter  5 , it includes an antenna which has the outward appearance of a pin, which further comprises a part  1  which may be rendered luminous. 
     This transmitter/receiver includes means which will be described hereinafter for activating the luminous part when an incoming call is detected, or when a key  3  is pressed by a user. The light may be produced in the form of flashes which attract the user&#39;s attention, for example, in the case of an incoming call. 
     An antenna for a transmitter/receiver such as that in FIG. 1 is represented in FIGS. 2A-2B. 
     The antenna represented in FIG. 2A comprises an envelope  6  made of a translucent material, and a mechanical support  7  which supports by any known means the envelope  6  and through which a light pipe  9  passes in which an electroluminescent diode  10  may send light. 
     In FIG. 2B, the same elements are represented alongside each other for the clarity of the representation. Furthermore, a metallic wire  8  in the form of a helical spring surrounds the light pipe and forms the electric part of the antenna. 
     The light pipe  9  is formed, for example, by a pin of transparent plastic material such as polymer. It comprises near to its end, that is to say, near to the end of the pin, inside the envelope  6  of a translucent material when the assembly is installed, a light-diffusing part  9 T formed by a treatment of a part of the surface so that light is diffused. The treatment consists, for example, of providing annular grooves due to which the light is diffused from inside the pipe to the outside. A frosted part may also perform this role. The light pipe  9  and the light-diffusing part  9 T form one part here. 
     The diffusing part could also comprise various separate elements spread over the length of the pipe to obtain special light effects. Obviously, at the end of the light pipe, an independent element could also be added to diffuse the light of the pipe. 
     In the case of a retractable antenna, the light pipe will also be formed by a flexible bundle of optical fibers. 
     In the cross-sectional view of FIG. 3, the translucent envelope  6 , the metallic spring  8  which forms the electric part of the antenna and surrounds the light pipe  9 , as well as the mechanical support  7  are represented as an assembly. A part of this antenna is represented on a larger scale in FIG. 4, making it possible to clearly show the annular grooves in the pipe  9  due to which the light inside the pipe is diffused to the outside between the whorls of the spring  8 . 
     A portable telephone as represented in FIG. 5 comprises a receiving circuit and a transmission circuit coupled both to an antenna duplexer  30 . The receiving circuit comprises a cascaded adjustable RF filter  31 , a mixer  32 , a switchable intermediate-frequency filter  33 , a detector  34 , a time-division multiple access (TDMA) controller  35 , a speech coder/decoder (CODEC)  36  and a loudspeaker  37 . The transmission circuit comprises a cascaded combination of a microphone  27 , the speech coder (CODEC)  36 , the time-division multiple access (TDMA) controller  35 , a modulator  38 , an oscillator  39 , a mixer  40  and a power amplifier  41 . A microprocessor  42  is provided for controlling the functionalities of the telephone. Various conventional characteristic features such as controlling a synthesizer  43  for obtaining a channel that has a particular frequency, controlling the TDMA controller  35 , sampling the keyboard  22  and controlling the display screen  21  will not be described in more detail here, because their operation is known per se. A memory  44  including a non-volatile part  45  and a volatile part  46  is associated to the microprocessor  42 . The non-volatile part  45  of the memory contains a program that deals with the functionalities of the telephone. Moreover, the device comprises power supply leads  48  and  49  connected to an exchangeable battery  51  for supplying power to the device. The antenna comprises, as described above, an electric part in the form of a spring  8  which is connected to the antenna duplexer  30 , and a light pipe  9  placed before a light source  10 . The source  10  is fed by a supply module  20  which is activated by the microprocessor in one of the cases mentioned above. For the case where a light is desired in the form of flashes, the microprocessor may comprise a program for activating the module  20  in brief successive periods, or, as a variant, the module  20  may comprise a circuit of the flip-flop type  21  for activating the light source  10  in bursts.