Patent Publication Number: US-2015081930-A1

Title: Tablet computer

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Taiwanese Application Nos. 102133215 and 102217280, both filed on Sep. 13, 2013. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a portable electronic device, and more particularly to a tablet computer that may operate as a peripheral device. 
     2. Description of the Related Art 
     Referring to  FIG. 1 , a conventional tablet computer  1  is shown to include a built-in display device  11 , a display control circuit  12  that controls operation of the display device  11 , and an HDMI (high-definition multimedia interface) port  13  for connecting to an external display device  2  (or an electronic device having a display device). The display control circuit  12  includes an HDMI output port  121  coupled to the HDMI port  13 . When the HDMI port  13  is not connected to the external display device  2 , the display control circuit  12  outputs to the display device  11  a video signal provided by a central processing unit  10  for display on the display device  11 . On the other hand, when the HDMI port  13  is connected to the external display device  2 , the display control circuit  12  outputs to the external display device  2  the video signal via the HDMI port  13  for display on the external display device  2 . In addition, the tablet computer  1  may access a USB (universal serial bus) storage unit  15  and employ a USB input unit  16  (e.g., a transparent touch panel stacked on a screen of the display device  11 ) that are built in the tablet computer  1  via a USB control circuit  14  (e.g., a USB host or a USB device that conforms to USB on-the-go specification). The USB control circuit  14  may further access an external USB peripheral device  3  (e.g., a USB storage unit) via a USB port  17 . 
     However, in conventional designs, an electronic device such as a desktop computer or a notebook computer may not employ the display device  11  of the tablet computer  1  to display video provided thereby, and may not use the USB input unit  16  to serve as an additional input interface, thereby limiting applications of the tablet computer  1 , which may adversely affect consumer interest. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a tablet computer that may be switched to operate as a computer device or a peripheral device. 
     According to the present invention, a tablet computer comprises: 
     a display device; 
     a video transmission port through which a video signal is to be inputted into or outputted from the tablet computer; 
     a display control circuit electrically connected to the display device, and including a video input port and a video output port; 
     an input unit for input operation by a user; 
     a data transmission port through which a data signal is to be inputted into or outputted from the tablet computer; and 
     a switching unit including a physical switch for user operation to switch between a first state and a second state, and a switching module electrically connected to the physical switch, the video transmission port, the display control circuit, the data transmission port and the input unit. 
     When the physical switch is in the first state, the switching module is configured to communicatively connect the video output port of the display control circuit to the video transmission port for enabling the display control circuit to output a video signal from the tablet computer via the video transmission port. 
     When the physical switch is in the second state, the switching module is configured to communicatively connect the video input port of the display control circuit to the video transmission port for enabling input of a video signal that is provided from the video transmission port into the display control circuit, the display control circuit configures the display device to display an image according to the video signal thus inputted, and the switching module is further configured to communicatively connect the input unit to the data transmission port, for enabling output from the tablet computer an input signal corresponding to input operation on the input unit by the user through the data transmission port. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of an embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a block diagram illustrating a conventional tablet computer; 
         FIG. 2  is a block diagram illustrating an embodiment of a tablet computer according to the present invention, operating in a computer mode; and 
         FIG. 3  is a block diagram illustrating the embodiment of the tablet computer according to the present invention, operating in a peripheral mode. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT 
     Referring to  FIGS. 2 and 3 , the embodiment of the tablet computer  4  according to this invention is shown to include a built-in display device  41 , a video transmission port  42 , a display control circuit  43 , a switching unit  44 , an interface control circuit  45 , an input unit  46 , a data transmission port  47 , a built-in storage unit  48 , and a CPU (central processing unit)  49 . 
     In this embodiment, the video transmission port  42  conforms to, but is not limited to, an HDMI (high-definition multimedia interface) specification, is configured to receive video and audio data, and is called an HDMI port  42  hereinafter. 
     In this embodiment, the interface control circuit  45 , the input unit  46 , the data transmission port  47  and the storage unit  48  conform to, but are not limited to, a USB (universal serial bus) standard, and are respectively called a USB control circuit  45 , a USB input unit  46 , a USB port  47  and a USB storage unit  48  hereinafter. The USB control circuit  45  may be a USB host device or a USB OTG (on-the-go) device, and is electrically connected to the USB input unit  46 , the USB port  47  and the USB storage unit  48  via the switching unit  44 . The USB input unit  46  may be a transparent touch panel stacked on a screen of the display device  41  for input operation by a user, and generates an input signal in response to the input operation. The USB control circuit  45  transmits the input signal received from the USB input unit  46  to the CPU  49  for subsequent processing, and accesses the USB storage unit  48  according to instructions from the CPU  49 . In addition, the USB control circuit  45  may access a USB peripheral device  6 , which is electrically connected to the USB port  47 , via the switching unit  44  and the USB port  47 . 
     In this embodiment, the display control circuit  43  is coupled to the display device  41  for controlling display operation of the display device  41 , and includes a video input port  431  and a video output port  432 . In this embodiment, the video input port  431  is configured to receive a video signal conforming to the HDMI specification and received from the HDMI port  42 , and the video output port  432  is configured to output a video signal conforming to the HDMI specification. The display control circuit  43  may include an HDMI transceiver, or separate HDMI transmitter and receiver, and the present invention should not be limited in this respect. 
     In this embodiment, the switching unit  44  includes a physical switch  440  for user operation to switch between a first state and a second state, and a switching module  441  including a first switch  442 , a second switch  443  and a switch control circuit  444 . 
     The first switch  442  is electrically connected to the switch control circuit  444 , the HDMI port  42  and the video input port  431  and the video output port  432  of the display control circuit  43 , and is operable by the switch control circuit  444  to electrically connect the HDMI port  42  to one of the video input port  431  and the video output port  432 . 
     The second switch  443  is electrically connected to the switch control circuit  444 , the USB control circuit  45 , the USB input unit  46 , the USB port  47  and the USB storage unit  48 , and is operable by the switch control circuit  444  to electrically connect the USB input unit  46  to one of the USB control circuit  45  and the USB port  47 . 
     The physical switch  440  is electrically connected to the switch control circuit  444  for switching the tablet computer  4  to operate between a computer mode and a peripheral mode therethrough. When the physical switch  440  is in the first state, the tablet computer  4  operates in the computer mode. In the computer mode, the switch control circuit  444  controls the first switch  442  to communicatively connect the video output port  432  of the display control circuit  43  to the HDMI port  42  for enabling the display control circuit  43  to output a video signal provided by the CPU  49  from the tablet computer  4  via the HDMI port  42 . The switch control circuit  444  further controls the second switch  443  to communicatively connect the USB control circuit  45  to the USB input unit  46  and the USB storage unit  48 , and to disconnect the USB input unit  46  from the USB port  47 . 
     Referring to  FIG. 2 , the tablet computer  4  is shown to operate in the computer mode. When an external display device  5  is electrically connected to the HDMI port  42  of the tablet computer  4 , the display control circuit  43  outputs the video signal provided by the CPU  49  to the video output port  432 , and the video signal thus outputted is transmitted to the external display device  5  through the first switch  442  and the HDMI port  42  for display by the external display device  5 . At the same time, the USB control circuit  45  may access the USB storage unit  48 , and receive the input signal from the USB input unit  46  through the second switch  443 . When the external USB peripheral device  6 , such as a USB storage unit, is connected to the USB port  47 , the USB control circuit  45  may further access the USB storage unit  6  through the second switch  443  and the USB port  47 . 
     When the physical switch  440  is in the second state, the tablet computer  4  operates in the peripheral mode. In the peripheral mode, the switch control circuit  444  controls the first switch  442  to communicatively connect the video input port  431  of the display control circuit  43  to the HDMI port  42  for enabling input of a video signal that is inputted through the HDMI port  42  into the display control circuit  43  via the video input port  431 , and the display control circuit  43  configures the display device  41  to display an image according to the video signal thus inputted. The switch control circuit  444  further controls the second switch  443  to communicatively connect the USB input unit  46  to the USB port  47 , for enabling output from the tablet computer  4  an input signal corresponding to input operation on the USB input unit  46  by the user through the USB port  47 . Since the USB control circuit  45  and the CPU  49  may not be used in the peripheral mode, the USB control circuit  45  and the CPU  49  may be configured to enter a sleep mode at this time. 
     Referring to  FIG. 3 , the tablet computer  4  is shown to operate in the peripheral mode. When an external electronic device  7 , such as a notebook computer or a desktop computer, is electrically connected to the HDMI port  42  and the USB port  47  of the tablet computer  4 , the electronic device  7  may provide a video signal, which is provided for display on its own display device  71 , to the display control circuit  43  of the tablet computer  4  via the HDMI port  42 , the first switch  442  and the video input port  431  for display on the display device  41 . At the same time, the electronic device  7  may access the USB storage unit  48  of the tablet computer  4  via the USB port  47  and the second switch  443 , and the input signal generated in response to input operation by a user on the USB input unit  46  may be transmitted to the electronic device  7  via the second switch  443  and the USB port  47  for relevant processing. The electronic device  7  may generate an image signal that corresponds to the input signal and that is provided to the display control circuit  43  of the tablet computer  4  via the HDMI port  42 , the first switch  442  and the video input port  431  for displaying on the display device  41  of the tablet computer  4  an image corresponding to the input operation. Furthermore, the electronic device  7  may execute instructions according to the input signal provided by the USB input unit  46 . 
     For example, when the electronic device  7  renders the USB input unit  46  (i.e., the transparent touch panel) to operate in a handwriting input mode, handwritten inputs on the USB input unit  46  may be transmitted to the electronic device  7  via the second switch  443  and the USB port  47  for proceeding with handwriting recognition, and the electronic device  7  may generate a corresponding image signal provided to the display control circuit  43  via the HDMI port  42 , the first switch  442  and the video input port  431  for display on the display device  41 . When the electronic device  7  renders the USB input unit  46  (i.e., the transparent touch panel) to operate in a drawing mode, drawn inputs on the USB input unit  46  may be recognized by the electronic device  7 , and the electronic device  7  may generate a corresponding image signal for display on the display device  41 . Then, the user may store the inputs (under the handwriting input mode or under the drawing mode) in either one of the USB storage unit  48  of the tablet computer  4  and a storage unit (not shown) of the electronic device  7 . 
     When the electronic device  7  renders the USB input unit  46  (i.e., the transparent touch panel) to operate in a touch control mode, the user may touch a specific touch control region of the USB input unit  46  or a region of the USB input unit  46  that corresponds to an icon displayed on the display device  41  to run a corresponding application program or to execute a corresponding instruction, or may use various touch gestures to proceed with operations (e.g., zoom-in, zoom-out, copy, etc.) on the image displayed on the display device  41 . 
     In summary, the user may switch the embodiment of the tablet computer  4  to operate in the computer mode or the peripheral mode by switching the physical switch  440 . When the tablet computer  4  operates in the computer mode, the HDMI port  42  serves as an output interface for the video signal, and the USB port  47  may be used for connection to an external USB peripheral device  6 . When the tablet computer  4  operates in the peripheral mode, the HDMI port  42  serves as an input interface for the video signal, and the USB port  47  may be used as a connection interface between the external electronic device  7  and the USB storage unit  48  and the USB input unit  46  that are built in the tablet computer  4 , such that the USB input unit  46  may serve as another input interface of the electronic device  7 . 
     While the present invention has been described in connection with what is considered the most practical embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.