Abstract:
A video display system is provided. The video display system includes: a first media device; and a second media device, wherein the first media device is connected to the second media device through a universal serial bus power delivery (USB PD) interface, and the first media device transmits both data and a protected video content to the second media device simultaneously through the USB PD interface, wherein the second media device displays the protected video content on a first electronic device through the USB PD interface.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application claims priority of Taiwan Patent Application No. 102146359, filed on Dec. 16, 2013, the entirety of which is incorporated by reference herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a video system, and in particular to a video display system capable of transmitting both video signals and data signals simultaneously by using a USB interface. 
         [0004]    2. Description of the Related Art 
         [0005]    If protected video content is to be displayed on a current video display system, a specific multimedia interface (e.g. HDMI or DisplayPort) is required for video/audio data transmission. However, a universal serial bus (USB) interface is usually equipped on most electronic devices (e.g. personal computers), so that it is convenient for the user to transfer data between the electronic device and a portable USB device. When a multimedia interface or a specific transmission interface having a larger data bandwidth is equipped, it may usually cost extra. Accordingly, there is a demand for a video display system capable of transmitting both the video/audio signals and data signals simultaneously by using the USB interface, so that a better user experience can be obtained. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    A detailed description is given in the following embodiments with reference to the accompanying drawings. 
         [0007]    In an exemplary embodiment, a video display system is provided. The video display system includes: a first media device; and a second media device, wherein the first media device is connected to the second media device through a universal serial bus power delivery (USB PD) interface, and the first media device transmits both data and protected video content to the second media device simultaneously through the USB PD interface, wherein the second media device displays the protected video content on a first electronic device through the USB PD interface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a simplified block diagram of a video display system  10  in accordance with an embodiment of the invention; 
           [0010]      FIG. 2  is a detailed block diagram of the video display system  10  in accordance with an embodiment of the invention; 
           [0011]      FIG. 3A  is a diagram illustrating the USB PD profiles in accordance with an embodiment of the invention; and 
           [0012]      FIG. 3B  is a diagram illustrating the USB PD pins used in the integration interface  124  in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
         [0014]      FIG. 1  is a simplified block diagram of a video display system  10  in accordance with an embodiment of the invention. As illustrated in  FIG. 1 , the video display system  10  may include a media device  100 , and a media device  200 , wherein the media device  100  and the media device  200  are connected to each other via the USB interface. In an embodiment, one of the media device  100  or the media device  200  can be regarded as a media provider or a source device, and the another one can be regarded as a media consumer or a sink device. For the purposes of description, the media device  100  is regarded as the source device, and the media device  200  is regarded as the sink device in the following embodiments. Briefly, the media provider may provide a media data stream and a high-definition digital content protection (HDCP) signal to the media consumer via the USB interface, and the media consumer may decode the media data stream to obtain images/videos, which are further displayed on a display unit. 
         [0015]      FIG. 2  is a detailed block diagram of the video display system  10  in accordance with an embodiment of the invention. As illustrated in  FIG. 2 , the media device  100  may include a processing unit  112 , a device management unit  114 , a source management unit  116 , a power supply device  118 , a USB interface  120 , and a multimedia interface  122 . The components  212 - 222  of the media device  200  correspond to those of the media device  100 . In the following embodiments, each component of the media device  100  is described. For one having ordinary skill in the art, the details of each component of the media device  200  are appreciated, and the details will be omitted here. In an embodiment, the multimedia interface  122  complies with the HDMI and/or DisplayPort specification, and the USB interface  120  complies with the universal serial bus power delivery (USB PD) specification. In some embodiments, the multimedia interface  122  and the USB interface  120  may be integrated into an integration interface  124  (e.g. an interface supporting the USB PD specification). The power supply device  118  is configured to provide power sources to each component of the media device  110 , and provide an operation voltage to the VBUS pin of the USB interface. The source management unit  116  is configured to receive a detection signal (e.g. a hot-plug signal) indicating whether any electronic device is plugged into the multimedia interface  122 , or receive a detection signal (e.g. a USB PD detection signal) indicating whether any electronic device is plugged into the USB interface  120 , and provide the detection signal to the device management unit  114 . The device management unit  114  is configured to control the power supply device  118  to provide power to related components. 
         [0016]    In addition, taking the DisplayPort specification as an example, the device management unit  114  may further determine whether the media device connected to the USB interface  120  is a video device supporting the USB PD specification or the HDCP specification. For example, the device management unit  114  may determine whether the media device  150  is connected to a video device supporting the USB PD specification. The device management unit  114  may further determine whether any electronic device is plugged into the multimedia interface  122 . Furthermore, the device management unit  114  may further transmit the extended display identification data (EDID) of the electronic device (e.g. electronic device  210 ) connected to the USB interface  120  to the processing unit  112  through an auxiliary channel, and transmit a hot-plug detection signal to the processing unit  112 , thereby informing the processing unit  112  whether an electronic device supporting the hot-plug function (e.g. complying with HDMI or DisplayPort specification) is plugged into the multimedia interface  122 . In an embodiment, the device management unit  114  can be implemented by a microcontroller. 
         [0017]      FIG. 3A  is a diagram illustrating the USB PD profiles in accordance with an embodiment of the invention. As illustrated in  FIG. 3A , profiles 0-5 are defined in the USB PD 1.0 specification, and each profile defines the operation voltage and current of the USB PD interface under different conditions. It should be noted that the operation voltage and current in some profiles are much larger than those in the USB 3.0/2.0 specifications. In addition, a profile 6 is further defined in the invention, and the operation voltage and current, which are used in the integration interface  124  for transmitting data and the protected video content, can be defined by the user. The device management unit  114  may know when to switch to high-speed transmission, receive the EDID, and transmit HDCP data according to the profile 6. 
         [0018]      FIG. 3B  is a diagram illustrating the USB PD pins used in the integration interface  124  in accordance with an embodiment of the invention. As illustrated in  FIG. 3B , there are 14 pins defined in the USB PD 1.0 specification, which are pin no. 1-13 and pin “shell”, wherein each pin has a corresponding signal name. It should be noted that there are only four pins (e.g. pins 1-4), which are VBUS, D−, D+ and GND, defined in the USB 2.0 specification, and the four pins are used for non-high-speed transmission. Furthermore, pins 10 and 11 defined in the USB PD specification are the detection pins PD DETECT 1 and PD DETECT 2, respectively. The media devices  100  and  200  detect whether the connected USB device supports the USB PD specification via the detection pins. In addition, the pins 12 and 13 defined in the USB PD specification are originally used for detecting whether any USB device is plugged into the USB interface  120 . The source management unit  116  may transmit the corresponding detection signals from the detection pins to the device management unit  114 . Afterwards, the device management unit  114  may transmit the EDID of the connected electronic device, the HDCP signal, and the hot-plug detection signal to the processing unit  112  via the auxiliary channel defined in the DisplayPort specification. Similarly, the processing unit  112  may also transmit the HDCP signal to device management unit  114  through the auxiliary channel, and the device management unit  114  may transmit the HDCP signal to the media device  200  through the USB interface  120 . 
         [0019]    It should be noted that the pins 10 and 11 defined in the USB PD specification are no longer used after detecting whether the connected USB device supports the USB PD specification. After detecting whether the connected USB device supports the USB PD specification, the media device  100  may use pins 5-9 defined in the USB PD specification as the data transmission pins defined in Lane 0 and Lane 1 of the DisplayPort specification, so that the video data can be transmitted to the electronic device  210  for display at a high transmission speed (e.g. 720P@30 fps). The processing unit  112  may only receive the standard EDID data and the detection signal of the USB PD device, and no extra determination mechanism is required. Specifically, when the processing unit  112  transmits both data and the protected video content via the integration interface  124 , the data can be transmitted via the pins defined in the USB 2.0 specification, and the video content, which has a corresponding HDCP signal, can be transmitted with Lane 0 and Lane 1 in the DisplayPort specification via pins 5-9 defined in the USB PD specification, where Lane 0 and Lane 1 indicate a signal differential pair. 
         [0020]    In an embodiment, for example, the media device  200  may be a portable USB video box including a USB 3.0 or USB 2.0 interface, a HDMI interface, and/or a DisplayPort interface. The media device  200  may detect whether any electronic video device (e.g. electronic device  230 ) is plugged into the HDMI or DisplayPort interface. For example, the device detection pins (e.g. PD DETECT 1 and PD DETECT 2) and insertion detection pin (e.g. INSERTION DETECT) can be used. The processing unit  212  of the media device  200  may obtain the EDID of the electronic device  230  via the auxiliary channel. Since the media device  200  is connected to the media device  100  via the USB PD interface, the processing unit  212  of the media device  200  may further transmit the EDID of the electronic device  230  to the processing unit  112  via the USB PD interface (e.g. via the VBUS pin). Meanwhile, when the processing unit  112  of the media device  100  determines that the protected video content can be transmitted to the media device  200  at a high speed, the processing unit  112  may transmit the protected video content to the media device  200  at a high speed via the high speed transmission and reception pins (e.g. pins 5-9 shown in  FIG. 3B ), and transmit the HDCP signal required in the decoding process via the VBUS pin. Subsequently, the processing unit  212  of the media device  200  may transmit the received HDCP signal and the protected video content to the electronic device  230  for decoding and displaying. 
         [0021]    While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.