Abstract:
An audio system with wireless speakers eliminates the long audio signal transmission lines between the amplifier and speakers. Sending the radio frequency signal from the amplifier to speakers utilizes wireless communication technique. Therefore, the problems in moving, assembling, and setting up the audio system can be solved.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an audio system, and more particularly, the present invention relates to an audio system with wireless speakers.  
         BACKGROUND OF THE INVENTION  
         [0002]    With the development and improvement of the technology, the quality of life becomes more and more important for most people. An audio system is one of the indices of better life, and almost becomes a necessity in a family. Due to the demands of high audio quality and user-friendly operation, storage media of music data evolves gradually from early discs, tapes to laser discs nowadays. Furthermore, quality of speakers also plays an important role for the development and improvement of an audio system.  
           [0003]    Referring to FIG. 1, a basic structure of a conventionally audio system is illustrated. The system includes a host machine  100 . The host machine  100  includes a radio  105 , a player  110 , a radio antenna  115 , and a speaker  120 . The frequency modulation (FM) or amplitude (AM) signal radiating in the air is received by the radio  105  via the radio antenna  115 . The electromagnetic signal then demodulated into audio data. The demodulated audio data are sent to the speaker  120  to sound. Alternatively, the speaker  120  may sound the audio data stored in a tape or disc and picked up by the player  110 .  
           [0004]    As the progress of the technology, demand of a high quality audio system becomes severe. The conventional basic audio systems cannot be satisfied by people anymore. In order to improve the quality of the audio system, design of speakers becomes even more complicated. The quantity and the arrangement of speakers are also taken into consideration as important issues. To improve the quality of output sound and to enrich the music, an amplifier is additionally provided to process audio data.  
           [0005]    Referring to FIG. 2, an improved audio system includes a host machine  200 , a group of speakers  220 , and audio signal transmission lines  225 . The host machine  200  includes a radio  205 , a player  210 , a radio antenna  215 , and an amplifier  230  in the same housing. The FM or AM signal radiating in the air is received by the radio  205  via the radio antenna  215 . Such a signal should be transferred into audio data by using a special demodulation technology. The demodulated audio data is sent to the amplifier  230  to be further processed in order to enhance its quality. Then, the quality-enhanced audio data is transmitted to the speakers  220 . Alternatively, the audio data stored in a tape or in a disc can be read and sent to the amplifier  230  where the quality of the audio data can be enhanced by the player  210 .  
           [0006]    Referring to FIG. 3, another improved audio system includes a host machine  300 , a group of speakers  320 , and audio signal transmission lines  325 . The host machine  300  includes a radio  305 , a player  310  and a radio antenna  315 . The audio system further includes an amplifier  330  separate from the host machine  300 . For both of the audio systems shown in FIGS. 2 and 3, audio signal transmission lines  325  are required for communicating the speakers with the amplifier  230  or  330 . Because of the specific position of speakers, audio data must be transmitted from the amplifier to each speaker via respective long signal transmission lines that might result in inconvenience and problems in moving, assembling or setting up. In addition, these long audio signal transmission lines are unpleasant to the eye.  
         SUMMARY OF THE INVENTION  
         [0007]    It is therefore an objective of this invention to provide an audio system with wireless speakers. The audio system with wireless speakers mainly eliminates the long audio signal transmission lines between the amplifier and speakers. Sending the audio data from the amplifier to speakers utilizes wireless communication technique. In this way, the present invention can solve the inconvenience in moving, assembling, and setting up of the audio system.  
           [0008]    In accordance with the object of this invention, this invention provides an audio system with wireless speakers, which is described as follows.  
           [0009]    The audio system comprises an audio data transmitter for modulating an audio data to a radio frequency signal; an audio data transmission antenna coupled to the audio data transmitter for radiating the radio frequency signal in the air; an audio data receiving antenna for receiving the radio frequency signal; an audio data receiver coupled to the audio data receiving antenna for demodulating the radio frequency to the audio data; and a speaker coupled to the audio data receiver for sounding the audio data.  
           [0010]    The audio data transmitter is preferably mounted on the amplifier of the audio system, and the audio data receiver is mounted on each of the wireless speakers.  
           [0011]    In another aspect of the present invention, the audio system includes a host machine for generating an audio data; an amplifier for receiving and transferring the audio data into a radio frequency signal; and at least one wireless speaker including an audio data receiving antenna, an audio data receiver, and a speaker. The audio data receiving antenna receives the radio frequency signal in the air, the audio data receiver transforms the radio frequency signal into an analog audio data signal, and the speaker sounds the analog audio data signal. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The invention will be more fully understood from the detailed description given herein below and the accompanying drawing, which are given by way of illustration only, and thus do not limit the present invention, and wherein:  
         [0013]    [0013]FIG. 1 shows a conventional basic audio system;  
         [0014]    [0014]FIG. 2 shows a conventional audio system with wired speakers;  
         [0015]    [0015]FIG. 3 shows another conventional audio system with wired speakers;  
         [0016]    [0016]FIG. 4 shows an embodiment of an audio system with wireless speakers according to the present invention;  
         [0017]    [0017]FIG. 5 shows the constellation of Quadrature Phase Shift Keying;  
         [0018]    [0018]FIG. 6 shows a structure of the radio frequency circuit of the audio data transmitter of FIG. 4; and  
         [0019]    [0019]FIG. 7 shows a structure of the radio frequency circuit of the audio data receiver of FIG. 4.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    Because of necessarily using several long audio signal transmission lines, it might result in inconvenience and some problems in moving or setting up the audio system. Therefore, an audio system with wireless speakers is introduced in this invention.  
         [0021]    [0021]FIG. 4 shows an embodiment of the present invention. An audio system with wireless speakers includes a host machine  400 , an amplifier  430 , and a group of wireless speakers  420 . The host machine  400  consists of a radio  405 , a player  410 , and a radio antenna  415 . Each of the wireless speakers  420  includes a speaker  425 , an audio data receiver  445 , and an audio data receiving antenna  450 . The amplifier  430  includes an audio data transmitter  435  and an audio data transmission antenna  440 .  
         [0022]    The radio  405  receives FM or AM radio frequency signal via its radio antenna  415 . The FM or AM radio frequency signal would be transformed to an audio data by using a special modulation technology and transferred to the amplifier  430 . Optionally, the audio data stored in a tape or in a disc can be read and sent to the amplifier  430  by the player  410 . The quality of the audio data is processed and improved in the amplifier  430 . Subsequently, the audio data would be up-converted to a radio frequency signal in the audio data transmitter  435 .  
         [0023]    In this embodiment, the audio data processed by the amplifier  430  is a series of digital signals so that Quadrature phase shift-keying (QPSK) modulation is chosen to modulate the audio data in the audio data transmitter  435 . Using this kind of modulation technology, each bite is represented by the phase of the continuous analog signal. As shown in FIG. 5, forty-five degree phase represents the bite “00”, one hundred thirty five degree phase represents the bite “01”, two hundred twenty five degree phase represents the bite “11”, and three hundred and fifteen degree phase represents the bite “10”.  
         [0024]    The structure of the audio data transmitter  435  is shown in FIG. 6. Direct-Conversion is chosen to up-convert the audio data from base band to radio frequency band via only once mixing. Referring to FIG. 6, the local oscillator  625  generates a sinusoidal signal whose frequency is the same as the frequency of the radio frequency signal. Two signals generated by the QPSK modulation in base band, so called an I signal and a Q signal, whose phases connote the series data are mixed with the sinusoidal signal by the two mixers  605  and  607  individually. The phase of the sinusoidal signal has to be 90-degree-shifted by a 90-Degree Phase Shifter  630  before mixing in the mixer  605 . Then, the outputs of two mixers are merged by using an adder  610 . This radio frequency signal in the output of the adder  610  is amplified by using a power amplifier  615 . Finally, it is radiated in the air by a audio data transmission antenna  440 .  
         [0025]    Referring FIG. 4 again, on the other side, each audio data receiving antenna  450  in the wireless speakers  420  receives the radio frequency signal from the audio data transmission antenna  440  instantly. The structure of the audio data receiver  445  is shown in FIG. 7, and the same technology is chosen again to demodulate the signal from radio frequency band to base band by only once mixing. Referring to FIG. 7, because the radio frequency signal received by audio data receiving antenna  450  is very weak, it has to be amplified by a low noise amplifier  715 . Then, this amplified radio frequency signal is divided into two amplified radio frequency signals and sent into the two mixers  705  and  707  individually. The sinusoidal signal generated by a local oscillator  725  is respectively mixed with these two amplified radio frequency signals by the two mixers  705  and  707 . Before mixing in the mixer  707 , the phase of the sinusoidal signal has to be adjusted by 90 degrees with a 90-degree phase shifter  730 . The amplified radio frequency signals and sinusoidal signals must be in phase, and then I signal and Q signal in base band can be obtained.  
         [0026]    Referring to FIG. 4, original audio data can be obtained via the audio data receiver  445 . Then, such a digital audio data must be transferred to an analog audio data and sent to speakers  425 .  
         [0027]    Taking advantage of this invention, long audio signal transmission lines between the amplifier and speakers are unnecessary. It also solves the problems in moving, assembling, or setting up the audio system with wired speakers.  
         [0028]    Other embodiments of the invention will appear to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples to be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.