Abstract:
The present invention relates to an electronic device that transmits audio-and-video (AV) signals with a universal serial bus (USB) connector, comprising a USB on-the-go (OTG) connector, a USB OTG controller, and a signal switch. The signal switch includes an AV signal end receiving an AV signal, a USB data signal end connected to a USB data signal port of the USB OTG controller, a USB/AV signal end connected to a data signal terminal of the USB OTG connector, and a switch signal end receiving a switch signal. Alternatively, the signal switch switches and connects the USB/AV signal end to the AV signal end, or switches and connects the USB/AV signal end to the USB data signal end, according to the switch signal.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an electronic device with a universal serial bus (USB) interface, and more particularly, to an electronic device equipped with a USB interface, transmitting USB signals and audio-and-video (AV) signals with the USB connector, and identifies an operation mode automatically to determine the transmission mode of the USB connector.  
       BACKGROUND OF THE INVENTION  
       [0002]     As regards any known electronic device with a USB interface, whether it is a conventional USB interface with four terminals or a USB interface with five terminals under the USB on-the-go (OTG) standard; the USB interface is only to transmit USB signals. Therefore, it is necessary to use an extra connector when the audio signals transmitted by any conventional electronic devices, for example, a MP3 player with a USB interface is not only equipped with a USB connector but also equipped with a headphone jack. This shows that the known electronic devices still rely upon a conventional audio connector, such as a headphone jack, for transmitting the analog voice signals produced.  
         [0003]     In order to overcome the disadvantage of the prior art, the inventor of the present invention provides an electronic device having a USB interface transmits USB and AV signals with the data signal terminal of the USB connector.  
       SUMMARY OF THE INVENTION  
       [0004]     Accordingly, an object of the present invention is to provide an electronic device transmits USB signals and AV signals with its USB connector and identifies an operation mode automatically in order to determine the transmission mode of the USB connector.  
         [0005]     To achieve the above object, the present invention provides an electronic device that transmits AV signals with a USB connector; the electronic device comprises a USB OTG connector, a USB OTG controller, and a signal switch. The signal switch comprises an AV signal end receiving AV signals, a USB data signal end connected to the USB data signal port of the USB OTG controller, a USB AV signal end connected to the data signal terminal of the USB OTG connector, and a switch signal end receiving switch signals. The signal switch switches the USB AV signal end to either the AV signal end or the USB data signal end in accordance with the switch signals.  
         [0006]     For a further understanding of the nature and advance of the invention, reference should be made to the following description in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The object and other objects and advantages of the present invention will become more apparent upon reading of the following detailed description and the accompanying drawings in which:  
         [0008]      FIG. 1  is a circuit diagram showing the electronic device of the first embodiment that transmits AV signals with a USB connector;  
         [0009]      FIGS. 2A-2D  are schematic block diagrams respectively illustrating the connection electronic devices with the first embodiment of the present invention;  
         [0010]      FIG. 3  is a flow diagram corresponding to program codes of the electronic device in accordance with the present invention;  
         [0011]      FIG. 4  is a circuit diagram showing the electronic device of the second embodiment that transmits AV signals with a USB connector;  
         [0012]      FIGS. 5A-5C  are schematic block diagrams illustrating the connection electronic devices with the second embodiment of the present invention respectively;  
         [0013]      FIG. 6  is a circuit diagram showing the electronic device of the third embodiment that transmits AV signals with a USB connector;  
         [0014]      FIGS. 7A and 7B  are schematic block diagrams illustrating the connection electronic devices with the third embodiment of the present invention respectively;  
         [0015]      FIG. 8  illustrates a preferred implementation of signals switch of the present invention; and  
         [0016]      FIG. 9  illustrates another preferred implementation by the signal switch of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     Referring to  FIGS. 1, 4  and  6 , an electronic device  10  of the present invention transmits AV signals with its USB connector which also serves to transmit USB signals. In practice, both the AV signals and the USB signals are transmitted, using a USB connector shared. When a user connects a USB OTG connector  101  (or a USB connector  101 ) of the electronic device  10  to a corresponding USB connector of the electronic device, such as a computer, a USB flash drive or a charger with an AV amplifier, the electronic device  10  automatically detects the connection mode of the USB OTG connector  101  (or the USB connector  101 ) and determines whether it serves to transmit AV signals or USB signals. Hence, it is not necessary for the electronic device  10  of the present invention to be specially equipped with a second connector to transmit AV signals.  
         [0018]      FIG. 1  is a circuit diagram showing the electronic device that transmits AV signals with a USB connector in the first embodiment. The electronic device  10  comprises at least a USB OTG connector  101 , a USB OTG controller  103 , and a signal switch  105 . Wherein the USB OTG connector  101  can be a USB OTG mini-AB connector, with a Vbus terminal  101   a  connected to a USB power supply  110 . A USB/battery management circuit  107  is connected to the USB power supply  110  and the USB OTG controller  103  respectively. An identification (ID) terminal  101   b  of the USB OTG connector  101  is electronically connected to an identification signal port  103   c  of the USB OTG controller  103 . The signal switch  105  can be a multiplexer and receives AV signals through AV signal ends  1051   a  and  1051   b ; the AV signals are generated by a digital/analog voice converter  109  connected to the AV signal ends  1051   a  and  1051   b  of the signal switch  105 . USB data signal ends  1053   a  and  1053   b  of the signal switch  105  are connected to USB data signal ports  103   a  and  103   b  of the USB OTG controller  103  respectively. USB/AV signal ends  1055   a  and  1055   b  of the signal switch  105  are connected to data signal terminals  101   c  and  101   d  of the USB OTG connector  101 . A switch signal end  1057  of the signal switch  105  receives a switch signal, alternatively switches and connects the USB/AV signal ends  1055   a  and  1055   b  to the AV signal ends  1051   a  and  1051   b  or to the USB data signal ends  1053   a  and  1053   b , according to the switch signal. The switch signal end  1057  is connected to a switch signal port  103   d  of the USB OTG controller  103 .  
         [0019]     Referring to  FIGS. 2A-2D , respectively illustrating the connection of electronic devices and the first embodiment of the present invention. In  FIG. 2A , the electronic device  20  is a USB slave device, such as a card reader, a digital camera or a cell phone, and is equipped with a 4-terminal USB connector  20   a . In  FIG. 2B , the electronic device  30  is a USB slave device and is equipped with a 5-terminal USB OTG connector  30   a , such as a USB OTG mini-B plug. When the electronic device  10  of the present invention is connected to the electronic device  20  or  30 , the signal received by the identification signal port  103   c  of the USB OTG connector  101  is a high-level identification signal; accordingly, the USB OTG controller  103  generates a high-level switch signal which is then sent to the switch signal end  1057  through the switch signal port  103   d  to make the signal switch  105  electronically connect the USB data signal ports  103   a  and  103   b , the USB data signal ends  1053   a  and  1053   b , the USB/AV signal ends  1055   a  and  1055   b , and the data signal terminals  101   c  and  101   d.    
         [0020]     In  FIG. 2C , the electronic device  40  is a USB host device, such as a computer, and configured with a 5-terminal USB OTG connector  40   a . In  FIG. 2D , the electronic device  50  is equipped with a 5-terminal USB OTG connector  40   a , but the electronic device  50  is a car charging kit, a FM transmitter or a docking unit, into which an AV amplifier is integrated, rather than a USB standard electronic device. When the electronic device  10  of the present invention is connected to the electronic device  40  or  50 , the signal received by the identification signal port  103   c  of the USB OTG controller  103  is a low-level identification signal; therefore, as described in  FIG. 3 , the USB OTG controller  103  executes program codes right away. The USB OTG controller  103  detects a high-level signal sent by the electronic device  40  or  50  via the Vbus terminal  101   a , and the USB OTG controller  103  performs the initialization of the slave mode to configure the electronic device  10  to function as a USB slave device. Afterward, the USB OTG controller  103  detects and determines whether has received a USB packet sent by the electronic device  40  or  50  via the data signal terminals  101   c  and  101   d  within a predetermined period (for example, within five seconds). Under such conditions, the USB packet only sent by the electronic device  40 . Upon receipt of a USB packet, the USB OTG controller  103  generates a high-level switch signal which is then sent to the switch signal end  1057  via the switch signal port  103   d  to make the signal switch  105  electronically connect the USB data signal ports  103   a  and  103   b , the USB data signal ends  1053   a  and  1053   b , the USB/AV signal ends  1055   a  and  1055   b , and the data signal terminals  101   c  and  101   d ; and the above-mentioned is the description of the USB signal transmission mode in  FIG. 3 . Of course, if the USB OTG controller  103  does not receive any USB packet, then the USB OTG controller  103  generates a low-level switch signal which is then sent to the switch signal end  1055  via the switch signal port  103   d  to make the signal switch  105  electronically connect the voice output end of the digital/analog voice converter  109 , the AV signal ends  1051   a  and  1051   b , the USB/AV signal end  1055   a  and  1055   b , and the data signal terminal  101   c  and  101   d ; and the above-mentioned is the description of the AV signal transmission mode in  FIG. 3 .  
         [0021]      FIG. 4  is a circuit diagram showing an electronic device that transmits AV signals with a USB connector in the second embodiment, whereas  FIGS. 5A-5C  are schematic block diagrams illustrating the connection of electronic devices and the second embodiment of the present invention respectively. In  FIG. 4 , both the identification signal port  103   c  and the switch signal port  103   d  of the USB OTG controller  103  are at an idle state, wherein the identification (ID) terminal  101   b  of the USB OTG connector  101  is connected to the switch signal end  1055 . Alternatively, the signal switch  105  of the second embodiment switches and connects the USB/AV signal ends  1055   a  and  1055   b  to the AV signal ends  1051   a  and  1051   b , or it switches and connects the USB/AV signal ends  1055   a  and  1055   b  to the USB data signal ends  1053   a  and  1053   b , according to the signal level of the identification (ID) terminal  101   b  of the USB OTG connector  101 .  
         [0022]     In  FIG. 5A , the electronic device  20  is identical to the electronic device shown in  FIG. 2A , that is, a USB slave device. In  FIG. 5B , the electronic device  60  is a USB host device, such as a computer, and it is equipped with a 4-terminal USB connector  60   a . After the electronic device  10  of the second embodiment is connected to the electronic devices  20  and  60 , the signal of the identification (ID) terminal  101   b  of the USB OTG connector  101  being of a high level, the signal switch  105  switches the high-level signal and electronically connects the USB data signal ports  103   a ,  103   b , the USB data signal ends  1053   a  and  1053   b , the USB/AV signal ends  1055   a  and  1055   b , and the data signal terminals  101   c  and  101   d  directly. The USB controller  103  detects the level of a signal sent by the electronic devices  20  and  60  via the Vbus terminal  101   a . In case of a high-level Vbus signal, which indicates that the electronic device  10  is connected to the electronic device  60 , the electronic device  10  will configure itself to function as a USB slave device. In case of a low-level Vbus signal, which indicates that the electronic device  10  is connected to the electronic device  20 , the electronic device  10  will configure itself to function as a USB host device.  
         [0023]     In  FIG. 5C , the electronic device  50  is the same electronic device shown in  FIG. 2D . Since the level of the voltage of the identification (ID) terminal  501  of the USB connector  50   a  is low, the signal of the identification (ID) terminal  101   b  of the USB OTG connector  101  is turned into a low-level identification signal. As a result, the signal switch  105  switches the high-level signal and electronically connects the voice output end of the digital/analog voice converter  109 , the AV signal ends  1051   a  and  1051   b , the USB/AV signal ends  1055   a  and  1055   b , and the data signal terminals  101   c  and  101   d  directly.  
         [0024]      FIG. 6  is a circuit diagram showing the third embodiment of the electronic device that transmits AV signals with a USB connector in accordance with the present invention, and  FIGS. 7A and 7B  are schematic block diagrams illustrating the connection of electronic devices and the third embodiment of the present invention respectively. Unlike its counterparts in the first and the second embodiments where a USB OTG connector is used, the electronic device  10  of the third embodiment uses a USB connector equipped with four signal terminals  101 . In addition, the electronic device  10  of the third embodiment uses a USB controller  103  having a USB slave port, whereas its counterparts in the first and the second embodiments use a USB OTG controller. In  FIG. 7A , the electronic device  60  is the same electronic device shown in  FIG. 5B . In  FIG. 7B , the electronic device  70  is equipped with a 4-terminal USB connector  70   a , and the electronic device  70  is a car charging kit, a FM transmitter or a docking unit rather than an electronic device of USB standard. In the third embodiment, the USB controller  103  generates a switch signal to be sent to the signal switch  105  via the switch signal port  103   d  and the switch signal end  1057 .  
         [0025]     In the third embodiment, the USB controller  103  executes program codes having the same process shown in  FIG. 3 . The USB controller  103  detects a high-level signal sent by the electronic device  60  or  70  via the Vbus terminal  101   a , then the USB controller  103  performs the initialization of the slave mode in order to configure the electronic device  10  to function as a USB slave device. Afterward, within a predetermined period of time (for example, within five seconds), the USB controller  103  detects and determines whether it has received a USB packet sent by the electronic device  60  or  70  via the data signal terminals  101   c  and  101   d . Under such a situation, only the electronic device  60  may send a USB packet. Upon receipt of a USB packet, the USB controller  103  generates a high-level switch signal which is then sent to the switch signal end  1057  via the switch signal port  103   d  to make the signal switch  105  electronically connect the USB data signal ports  103   a  and  103   b , the USB data signal ends  1053   a  and  1053   b , the USB/AV signal ends  1055   a  and  1055   b , and the data signal terminals  101   c  and  101   d . When there is no USB packet received by the USB controller  103 , a low-level switch signal generated by USB controller  103  and sent to the switch signal end  1055  via the switch signal port  103   d  to make the signal switch  105  electronically connect the voice output end of the digital/analog voice converter  109 , the AV signal ends  1051   a  and  1051   b , the USB/AV signal end  1055   a  and  1055   b , and the data signal terminal  101   c  and  101   d.    
         [0026]     To sum up, the aforesaid first through third embodiments are illustrated by way of examples involving right channel analog signals and left channel analog signals, it is to be understood that the invention is not limited thereto. Moreover,  FIG. 8  illustrates an embodiment of the variations in the types of signals switched to by a signal switch in accordance with the present invention. In  FIG. 8 , digital signals  112   a  and  112   b  can be alternatively, for example, a right channel digital signal and a left channel digital signal respectively, or an encoded digital AV signal.  FIG. 9  illustrates another embodiment of the variations in the types of signals switched to by a signal switch in accordance with the present invention. In  FIG. 9 , a digital signal  114  can be, for example, a synthesized digital signal of the right and left channels, whereas a video signal  116  is either a dynamic movie signal or a static image signal.  
         [0027]     The electronic device  10  of the present invention can be a voice player and an AV player like a MP3 player; also, the electronic device  10  can certainly be a portable electronic device that combines the functions of voice playing and AV playing, such as a palm-held MP3 player, a palm-held MPEG4 player, or a recording pen.  
         [0028]     The electronic device  10  can identify an operation mode automatically to transmit USB signals and AV signals with a USB OTG connector (or USB connector). Accordingly, the connection of present invention is superior to the conventional electronic device equipped with a USB interface.  
         [0029]     While the invention has been described by way of examples and in terms of preferred embodiments, 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 according to the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.