Patent Publication Number: US-2007111700-A1

Title: Car type MP3 sound converter

Description:
BACKGROUND OF THE INVENTION  
      (a) Field of the Invention The present invention relates to a sound converter, and more particularly to a car type MP3 sound converter that is able to directly transmit MP3 music stored in a peripheral device or a general storage medium through a transmission interface of a USB (Universal Serial Bus) connector interface having an automatic recharging function or a memory card connector. Moreover, the music is transmitted through a frequency modulation transmitter module by means of a wireless method or through a sound output jack.  
      (b) Description of the Prior Art  
      All sound formats are digitized and stored using digital coding methods, which can be generally divided into two types including sound wave data and synthesized sound effects (MIDI). Wherein, sound wave data undergoes sampling conversion to a digital format through an analog-to-digital converter, and is then stored in a storage medium of a computer, whereas synthesized sound effects are assembled from a computer built-in sound source. Because the higher the sampling frequency of sound wave data converted to digital format, the larger the storage space required, thus, similarly, the higher the resolution of the sampling, the larger the storage space required.  
      For example, a common sound wave format is wave data, which is generally stored as a *.wav file. However, the storage space occupied by a file in wave format containing one minute of sound wave data is over 10 MB, which is a considerable waste of storage space. In order to resolve this problem, the MP3 sound wave format was developed that uses MPEG Audio Layer 3 technology, which employs a 10 to 1 or even a 12 to 1 compression ratio to compress the sound wave data, thereby forming a substantially smaller file size. The compression method utilized exploits an inadequacy of human hearing in certain areas, and employs destructive compression to remove high and low audio frequencies that cannot be heard by the human ear, thereby converting the sound wave data into a digital compressed file of substantially smaller size.  
      Because the storage space required to store a file in MP3 sound wave format is small, the file can be saved to a storage medium including a compact disc, a memory card, a mobile disc, and so on. For this reason, functionality to transmit MP3 has been added to some mobile discs, thereby transforming the mobile disc into a MP3 mobile disc, and enabling a user to play decoded audio signals using an earphone or speakers plugged into an earphone jack (that is, a general sound output jack).  
      Accordingly, MP3 sound converters designed exclusively for car use have appeared on the market, which enable the car stereo equipment to acquire the decoded audio signals through the MP3 sound converter, and broadcast the sound using speakers connected to the car stereo, thereby providing the car stereo with functionality to play MP3 music. Similar early MP3 sound converters used a cassette tape type adaptor cable to transmit audio signals to the car stereo. However, because of the inconvenience in using the adaptor cable, and the problem of some car stereos not having a cassette-cartridge, thus, the sound converter underwent further improvement to be able to utilize a frequency modulation (FM) transmitter module, which transmitted the audio signals using a wireless method, and a frequency modulation receiver of the car stereo received and broadcasted the music, thereby enhancing applicability and facilitation in use of the car type MP3 sound converter.  
      However, presently, the majority of car type MP3 sound converters commonly seen on the market are only provided with a convert and transmit mode function, and, thus, are only able to acquire decoded audio signals from devices capable of MP3 broadcasting. Hence, the car stereo is unable to broadcast MP3 music stored in MP3 music storage media commonly used by the general user, such as memory cards, USB mobile discs, and so on.  
     SUMMARY OF THE INVENTION  
      In light of the aforementioned, the present invention provides a car type MP3 sound converter comprising a case having a cigarette lighter connector, within which is disposed a MP3 decoder, a frequency modulation transmitter module and a printed-circuit board constructed from related control circuits, wherein the printed-circuit board is further configured with a sound input jack, a sound output jack, a USB connector interface, a memory card connector and buttons having related operating functions. Moreover, an electrical connection is made with the cigarette lighter connector of the case.  
      Accordingly, the car type MP3 sound converter of the present invention apart from being provided with a transmission mode and conversion function that enables transmitting audio signals using a wireless method, moreover, a transmission interface of the USB connector interface or the memory card connector is used to acquire MP3 sound wave data stored in general storage media, which the built-in MP3 decoder then decodes and transmits. More particularly, because the present invention is provided with USB automatic recharging and mobile telephone connection functionality, thus, a user can listen to MP3 music while simultaneously recharging a mobile telephone and functioning as a handsfree receiver.  
      To enable a further understanding of said objectives and the technological methods of the invention herein, brief description of the drawings is provided below followed by detailed description of the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows an exploded structural view of a sound converter according to the present invention.  
       FIG. 2  shows a block diagram depicting structure of the sound converter according to the present invention.  
       FIG. 3  shows an elevational view depicting an exterior appearance of the sound converter according to the present invention.  
       FIG. 4  shows an elevational view depicting an exterior appearance of the sound converter from another viewing angle according to the present invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIG. 1 , which shows the basic structural assembly of a car type MP3 sound converter of the present invention, structured to comprise a case  10 , a MP3 decoder  20 , a frequency modulation transmitter module  30 , and a printed-circuit board  40  constructed from related control circuits.  
      The case  10  is the primary structural body used by the MP3 sound converter for disposing related mechanistic structural members therein. In an embodiment of the present invention, the case  10  is assembled from a base  11  and an upper cover  12 , and the base  11  is formed by butt joining two symmetrical lower case covers  111 , which forms a cigarette lighter connector  13  after assembling the lower case covers  111 , within which is disposed a fuse  131  (see  FIG. 2 ) that facilitates forming an electric outlet connection with a cigarette lighter and acquiring the necessary power supply to operate the sound converter.  
      Referring to  FIGS. 1, 2 ,  3  and  4 , the MP3 decoder  20  and the frequency modulation transmitter module  30  are directly disposed on the printed-circuit board  40 . Moreover, the printed-circuit board  40  is further configured with a sound input jack  41 , a sound output jack  42 , a USB connector interface  43 , a memory card connector  44  and a related operating push button set  45 . When an electrical connection is made with the cigarette lighter connector  13  on the case  10 , the printed-circuit board  40  then inputs an electrical supply through the cigarette lighter connector  13 , whereafter the printed-circuit board  40  integrates circuit functions of the MP3 decoder  20 , the frequency modulation module  30  and the operating push button set  45  with the transmission interfaces of sound input jack  41 , the sound output jack  42 , the USB connector interface  43  and the memory card connector  44 .  
      In an embodiment of the MP3 sound converter of the present invention, the operating push button set  45  comprises a play button  451 , next tune switchover button  452 , last tune switchover button  453  and a frequency channel selection button  454 , and the memory card connector  44  serves as a memory card slot connector for a SD/MMC memory card.  
      Accordingly, the sound input jack  41  is able to acquire audio signals transmitted by a peripheral device including a portable CD player, a MP3 mobile disc, and so on. Moreover, the audio signals are transmitted through the frequency modulation transmitter module  30  using a wireless method. The transmission interface of the USB connector interface  43  or the memory card connector  44  is then used to acquire the MP3 sound wave data stored in a general storage medium (such as a mobile disc, a memory card, and so on), whereafter the built-in MP3 decoder  20  implements decoding and transmitting of the acquired MP3 sound wave data. The audio signals after undergoing decoding are transmitted through the frequency modulation transmitter module  30  using a wireless method or are output through the sound output jack  42 , and earphones or speakers are used to broadcast the sound waves, thereby effectively resolving the problem of car stereos being unable to broadcast MP3 music stored in storage media, such as memory cards, USB mobile discs, and so on.  
      According to the aforementioned, the present invention provides a superior car type MP3 sound converter, thus, a new patent application is proposed herein.  
      It is of course to be understood that the embodiments described herein are merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.