Patent Publication Number: US-2005135634-A1

Title: Wireless transmission device of surround sound stereo system

Description:
FIELD OF THE INVENTION  
      The present invention relates to a wireless transmission between a subwoofer speaker, a left surround speaker, a right surround speaker, and a stereo system.  
     BACKGROUND OF THE INVENTION  
      In general, a surround sound stereo system usually installs a front left speaker, a front right speaker, and a center speaker in the front, a surround left speaker and a surround right speaker at the back, and a subwoofer at an appropriate position of the environment to achieve the so-called 6-channel (or 5.1-channel) surround sound effect.  
      The traditional way of setting up a surround sound stereo system generally uses cables for the signal transmission between each speaker and the main stereo system, and the main stereo system is usually installed in the front of the audience. Therefore, the cables of the front left speaker, front right speaker, and center speaker will not be in the way of audience&#39;s movement path, but the cables between the surround left speaker, surround right speaker, and the main stereo system may have to cross the audience&#39;s movement path and thus becoming an obstacle to the audiences. More seriously, the cable may be pulled by accident and topple or damage the stereo system.  
      Therefore, a wireless stereo system as shown in  FIG. 1  was introduced to the market, and such wireless stereo system used a wireless transmission technology to transmit signals between left and right surround speakers  23 ,  24  and the stereo system  10  in order to leave out the cable installation between the left and right surround speakers  23 ,  24  and the stereo system  10 . The front left and front right speakers  21 ,  22 , center speaker  26 , and subwoofer  25  still use a cable  30  to transmit signals with the main stereo system  10 . However, the whole set of equipment requires to install a signal transmitter (not shown in the figure) in the main stereo system  10  and a signal receiver  40  in each of the left surround speaker and right sound speaker  23 ,  24 , which will greatly increase the cost of the whole stereo system. In addition, the volume of the left and right surround speakers  23 ,  24  will become bulky after the signal receiver  40  is installed.  
      In  FIG. 2 , a signal receiver  40  is installed in the right surround sound  24 , and a cable  30  is used to transmit signals for the left and right surround speakers  23 ,  24 . Such stereo system can leave out the installation of signal receivers, and thus lowering the cost of the whole stereo system. However, the stereo system of this kind has the shortcoming of having different sized left and right surround speakers  23 ,  24 .  
      Please refer to  FIG. 3  for a stereo system which installs an additional independent signal receiver  40  and uses a cable  30  for the signal transmission between the left and right surround speakers  23 ,  24  in order to solve the problem of the different sized left and right surround speakers  23 ,  24 . However, such arrangement not only adds components to the system, but also keeps using a cable  30  for the signal transmission between the subwoofer  25  and the stereo system  10 . Therefore, the cable  30  is still in the way of the audience&#39;s movement path.  
     SUMMARY OF THE INVENTION  
      The primary objective of the present invention is to provide a wireless transmission device for the surround sound stereo system by using a front mixer to mix the subwoofer signal of the main stereo system with the left and right surround signals into a 2-channel signal and transmit the signal by a radio frequency. After the subwoofer receives and decodes the signal, and the rear crossover separates the subwoofer signal and sends the subwoofer signal, left surround signal, and right surround signal respectively to the corresponding speakers for the playback, such arrangement provides a wireless signal transmission between the subwoofer and the main stereo system and also allows the signal transmission for the subwoofer and left surround speaker with the main stereo system without using a cable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an illustrative diagram of installing a conventional surround sound stereo system.  
       FIG. 2  is an illustrative diagram of installing a main stereo system and surround speakers using a prior-art wireless transmission method.  
       FIG. 3  is an illustrative diagram of installing a main stereo system and surround speakers using another prior-art wireless transmission method.  
       FIG. 4  is an illustrative diagram of the structures of the front low-pass filter, front high-pass filter, front mixer, radio frequency transmitting module, and front power supply circuit of the present invention.  
       FIG. 5  is an illustrative diagram of the structures of the rear mixer, radio frequency receiving module, rear low-pass filter, rear high-pass filter, and rear power supply circuit of the present invention.  
       FIG. 6  is an illustrative diagram of installing the speakers and main stereo system of the present invention.  
       FIG. 7  is an illustrative diagram of installing the speakers and main stereo system according to another preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      To make it easier for our examiner to understand the objective of the invention, its structure, innovative features, and performance, we use a preferred embodiment together with the attached drawings for the detailed description of the invention.  
      Please refer to  FIGS. 4 and 5  for the wireless transmission device of surround sound stereo system of this invention. The basic structure of the whole wireless transmission device comprises: 
          at least one front mixer  61 , for mixing the subwoofer signal outputted from the main stereo system into the left and right surround signals; wherein the left and right surround signals outputted from the main stereo system after being processed by the front high-pass filter  62  enter the front mixer  61 , and the subwoofer signal outputted from the main stereo system after being processed by the front low-pass filter  63  enters the front fixer  61 ;     a radio frequency transmitting module  71 , comprising a modem  73 , a radio frequency transmitter  75 , and an antenna  74  and receiving the 2-channel signal produced by mixing the subwoofer signal of the main stereo system and the left and right surround signals through a cable  30 , and transmitting the 2-channel signal by a radio frequency, and having a front power supply circuit  81  for driving the operation of the radio frequency transmitting module  71 ;     a radio frequency receiving module  72 , comprising a modem  73 , a radio frequency receiver  76 , and an antenna  74 , for receiving the signal transmitted from the radio frequency transmitting module  71 ;     a decoder  80 , coupled to the radio frequency receiving module  72 , for decoding the signal received by the radio frequency receiving module  71 , and having a rear power supply circuit  92  for driving the operation of the radio frequency receiving module  72 ;     at least one rear crossover  67 , comprising a rear distributor  64 , a rear high-pass filter  65 , and a rear low-pass filter and all of these components being disposed at the rear section of the decoder  80  for separating the subwoofer signal from the left and right surround signals and outputting the subwoofer signal, left surround signal, and right surround signal to the corresponding speakers for the playback; wherein the left and right surround signals separated from the rear distributor  64  are recovered by the high-pass filter  65  and outputted to the left and right surround sound speakers  23 ,  24  via the amplify circuit  93 , and the subwoofer signal separated by the rear distributor  64  is recovered by the rear low-pass filter  66  and outputted to the subwoofer  25  via the amplify circuit  93 .        

      The foregoing components constitute a wireless transmission device as shown in FIGS.  5  for outputting the subwoofer signal, left surround signal, and right surround signal of the main stereo system  10 , particularly integrating the rear distributor  64 , radio frequency receiving module  72 , rear high-pass filter  65 , rear low-pass filter  66 , amplify circuits  83 , rear power supply circuit  92 , and subwoofer  25  into a housing  53  and providing a port  54  and a cable  30  for connecting the left and right surround speakers  23 ,  24 . The actual installation of the whole set of stereo system  10  as shown in  FIG. 6  can provide the wireless transmission of signals between the subwoofer  25  and the main stereo system  10 , and allow signal transmission between the left and right surround speakers  23 ,  24  and the main stereo system  10  without using a cable  30 . Of course, the whole main stereo system  10  also can use a cable  30  to connect the front left and right speakers  21 ,  22  and the center speaker  26  as shown in  FIG. 7  for the application.  
      In addition, the front mixer  61  and radio transmitting module  71  of this invention can be installed inside the main stereo system  10  and the operation of the radio frequency transmitting module  71  is driven directly by the power supply circuit of the main stereo system  10 . Alternatively, the front high-pass filter  62 , front low-pass filter  63 , and front mixer  61  are integrated into the housing  51  as shown in  FIG. 4 , and a port  54  is set for connecting the circuit of the main stereo system  10 . The radio frequency transmitting module  71  is installed in another housing  51  and a connector  55  is installed for the signal connection and power supply. Such arrangement can separate the radio frequency transmitting module  71  with the main stereo system  10  and place the radio frequency transmitting module  71  at a better transmitting position.  
      Of course, the subwoofer signal can be selectively mixed into the left surround signal or the right surround signal or both to enhance the subwoofer performance.  
      In summation of the above description, the present invention discloses a better and operable wireless transmission mode for the surround sound stereo system and enhances the performance of the conventional structure, and further complies with the patent application requirements and is submitted to the Patent and Trademark Office for review and granting of the commensurate patent rights.  
      While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.