the present invention is described with the preferred embodiments and accompanying drawings . it should be appreciated that all the embodiments are merely used for illustration . although the present invention has been described in terms of a preferred embodiment , the invention is not limited to this embodiment . the scope of the invention is defined by the claims . modifications within the spirit of the invention will be apparent to those skilled in the art . referring to fig1 , a block diagram shows the preferred embodiment of the bluetooth audio signal relay of the present invention . it should be noted that all the possible elements of the present invention are illustrated , but not every element in the drawing is essential . most main elements could be mounted on a printed circuit board ( pcb ) 101 , but there are some elements not mounted on pcb 101 in fig1 . however , in another embodiment of the present invention , all of the elements may be mounted on the pcb . it should be noted that the present invention should encompass every possible way to assemble the elements . according to the preferred embodiment of the present invention , a bluetooth chip 103 , memory 104 , a codec chip 105 , a microphone 109 , a speaker 110 and audio jacks 111 , 112 are mounted on pcb 101 . an antenna 102 is applied to transmit and receive the bluetooth signals . in the preferred embodiment of the present invention , the bluetooth audio relay may pair with a plurality of devices . as the bluetooth audio signals come from the paired audio source wirelessly , the antenna 102 would transfer these signals to the bluetooth chip 103 , such as the commercial product zv4301 of zeevo ® or bc3 - mm of csr ®, which is preferably able to process the stereo signals . other bluetooth chip which can process only the mono audio signals may also be adopted in another embodiment of the present invention . the bluetooth chip 103 would transform the received bluetooth signals into digital audio signals , and transfer them to the codec chip 105 . the codec chip 105 is coupled to the bluetooth chip 103 and applied to transform the digital audio signals into analog audio signals . the analog audio signals then are outputted via an earphone or a speaker . various available codec chips 105 could be adopted in the present invention , such as the commercial product wm8731 of wolfson ® or dac cs4340 of cirrus logic ®. the present invention may comprise a speaker 110 coupled to the codec chips 105 , and the speaker 110 could be a normal earphone or speakerphone . however , the bluetooth audio signal relay is preferably not equipped with any built - in earphone or speaker to improve the mobility and reduce the manufacture cost of the bluetooth audio signal relay . besides , plural audio jacks 111 , 112 are applied as the main audio output port to replace the built - in earphone or speaker . although there are merely two audio jacks illustrated in fig1 , the number of the audio jacks is not limited to two and could be modified according to various situations or demands . in general , the number of audio jacks is based on the support of the codec chip 105 and the consideration of manufacture cost . besides , the audio jacks of the present invention preferably include at least one audio out jack for directly connecting the earphone or other speaker devices . according to another embodiment of the present invention , the audio jacks may further include at least one line out jack for connecting with the audio equipment with an amplifier , and therefore the bluetooth audio signal relay could work as a music streaming device . in addition , the bluetooth audio signal relay is preferably controlled wirelessly by a computer or mp3 player with a ( built - in or external ) transmitter . it should be noted that the bluetooth audio signal relay can include every possible collection of various audio jacks . moreover , the present invention may further includes a line in jack for transforming external analog audio signals into bluetooth signals and wirelessly transmitting these transformed signals to other bluetooth devices . the aforementioned examples of audio jacks are described for illustration , instead of limitation . a microphone 109 could be included in the bluetooth audio signal relay of the present invention and coupled to the codec chip 105 . in this situation , the bluetooth audio signal relay may be applied as a hand - free device of a cellular phone . however , the bluetooth audio signal relay may have no built - in microphone or merely provide a microphone jack to connect an external microphone . the microphone 109 and the speaker 110 are both optional elements , which can be added or omitted on demand . besides , a user may vocally and wirelessly dial someone by using the microphone 109 of the bluetooth audio signal relay . the memory 104 is mainly applied for storing plural programs or the phone book . typically , the memory 104 is coupled to the bluetooth chip 103 also . the operation of the bluetooth chip 103 may base on these programs , and the call information may be displayed according to the data of phone book . the programs include the audio controlling program , the hand - free program and the switch program . besides , the bluetooth audio signal device could include a built - in display 115 to display the call information , wherein the display 115 may be a liquid crystal display ( lcd ) or a light emitting diode displayer ( led displayer ). the call information may be provided by the cellular phone or depend on the phone book in the memory . moreover , if the memory 104 keeps data of phone book , the user is able to wirelessly dial certain phone number in the phone book by using the input device 107 , such as keys or buttons . the types of the display 115 are not limited to the above examples , but may further include other light or power - saving display means . the aforementioned types of the display are enumerated merely for illustration , instead of limitation . the present invention could include various kinds of memory , such as flash memory , read only memory ( rom ) or random access memory ( ram ). however , the flash memory is the preferred choice , such as the current commercial product sst39vf800a of sst ® or at49bv802a of atmel ®. the audio controlling program is applied to enable the bluetooth audio signal relay to process the stereo signals , and the hand - free program is applied to enable the bluetooth audio signal relay to operate as a hand - free device of a cellular phone . since the bluetooth audio signal relay may pair with plural bluetooth devices , for example , the media player ( pc ) and the cellular phone , the switch program is applied to enable the bluetooth chip 103 to switch from one mode to another , manually or automatically . for instance , a calling signal is provided to the bluetooth audio signal relay as the cellular phone receives the call . the bluetooth chip 103 in the bluetooth audio signal relay would automatically switch the headset mode to the hand - free mode by the switch program in the memory 104 . besides , the hand - free mode would be switch back to the headset mode after the call is finished . in another embodiment of the present invention , the bluetooth audio signal relay may comprise an input device 107 coupled to the bluetooth chip 103 for providing external instructions to the bluetooth chip 103 . the input device 107 may be the keys or buttons on the casing of the relay , or the built - in microphone 109 with vocal input ability . besides , the switch program of the relay could also switch the modes manually with various input devices 107 . the power supply 106 is preferably a battery , especially a rechargeable battery , such as the lithium ion ( li - ion ) battery , the nickel metal hydride ( ni - mh ) battery , the nickel cadmium ( ni — cd ) or the lithium polymer battery . besides , the relay may also comprise an external power port 113 on the casing . the external power port 113 is an optional element and not essential to the present invention , and could therefore be omitted on user &# 39 ; s demand or commercial considerations . for example , the external power port 113 may be an electric plug for providing power to operate the relay or charge the chargeable battery . the bluetooth audio signal relay may further include an indicator light 108 coupled to the bluetooth chip 103 for indicating the operation or linking status . similarly , the indicator light 108 is an optional element and could be added or omitted on demand . fig2 through fig4 illustrate the casing 20 of the bluetooth audio signal relay . as we can see , the relay may comprise a back splint 21 to fix the relay on the collar , the pocket or the cuff of the clothes , and therefore increase the mobility and convenience . moreover , the indicator 25 ( corresponding to no . 108 in fig1 ) is used to indicate the linking or operation status , and plural keys or buttons 22 are included in the input devices 107 of the relay . the casing 20 may have an opening 23 corresponding to the external power port 113 , and the circle openings 24 correspond to the audio jacks 111 , 112 . the button 26 is used to power on and power off the relay . it should be noted that there are two phone jacks 24 , five keys 22 , 26 and two indicator lights 25 in the outward appearances , but they are presented and described for illustration , instead of limitation . the present invention is not limited to the aforementioned embodiments and the drawings , but should encompass any possible combination of these elements . the present invention operates as the audio relay for any audio device with bluetooth transceiver , such as the computer , the portable flash drive , the mp3 player , the television , the hi - fi equipment or the pda . the audio source of the bluetooth audio signal relay should include every audio device with built - in or external bluetooth transceiver ( the bluetooth dangle ). in addition , the input device , such as keys or buttons , of the present invention may also be applied as the remote control of the audio devices . for example , the user may use the bluetooth audio signal relay to control the mp3 player to play , stop , pause , forward or rewind the songs , and the controlling program in the memory 104 is required to achieve such function . since the bluetooth protocol is a non - directional wireless communication standard , the present invention possesses the advantage of high mobility , and is not restricted to certain fixed direction . in addition , the present is dissimilar to the normal bluetooth earphone which is only able to receive and play the audio content , but could relay the audio signals to any external speaker or normal earphone . hence , the present invention possesses advantage of high expandability . besides , the earphone or speaker may be omitted , so the bluetooth audio signal relay is lighter and smaller than the conventional bluetooth earphone . in addition , since the power consuming is relatively low in the bluetooth device , the weight of battery therein is reduced , and the duration of usage is therefore prolonged . in conclusion , the manufacture cost of the present invention would be remarkably reduced because no built - in earphone is required . accordingly , the marketing competitiveness of the bluetooth audio signal relay is highly raised . the user could appreciate the music in every environment by any convenient device without the limitation of built - in earphone or speaker . as is understood by a person skilled in the art , the foregoing preferred embodiments of the present invention are illustrated of the present invention rather than limiting of the present invention . it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims , the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structure . while the preferred embodiment of the invention has been illustrated and described , it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention .