Abstract:
A motherboard includes a video signal switching circuit. The video signal switching circuit includes a video signal output unit, a video interface, a detecting unit, a control unit, and a signal conversion unit. The video signal output unit is used to output a first video signal. When the detecting unit detects that a first cable is connected to the video interface, the control unit outputs a first control signal to the signal conversion unit, the signal conversion unit does not operate, and the video interface receives the first video signal. When the detecting unit detects that a second cable is connected to the video interface, the control unit outputs a second control signal to the signal conversion unit, the signal conversion unit operates and converts the first video signal into a second video signal, and the video interface receives the second video signal.

Description:
FIELD 
       [0001]    The subject matter herein generally relates to motherboards and particularly to a motherboard with a video signal switching circuit. 
       BACKGROUND 
       [0002]    Generally, motherboards of electronic devices (such as computers and servers) can output different kinds of video signals (such as a high definition multimedia interface video signal and Displayport video signal). However, each video signal needs a video circuit and a video interface to be output, which wastes resources and occupies space of the motherboards. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    Implementations of the present technology will now be described, by way of examples only, with reference to the attached figures. 
           [0004]      FIG. 1  is a block diagram of an embodiment of a motherboard comprising a video signal switching circuit, wherein the video signal switching circuit comprises a video signal output unit, a video interface, a detecting unit, a control unit, a signal conversion unit, a channel signal output unit, and a channel signal transmission unit. 
           [0005]      FIG. 2  is a circuit diagram of the detecting unit and the control unit of  FIG. 1 . 
           [0006]      FIG. 3  is a circuit diagram of the video signal output unit, the video interface, and the signal conversion unit of  FIG. 1 . 
           [0007]      FIG. 4  is a circuit diagram of the video interface, the channel signal output unit, and the channel signal transmission unit of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure. 
         [0009]    Several definitions that apply throughout this disclosure will now be presented. 
         [0010]    The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like. 
         [0011]      FIG. 1  illustrates an embodiment of a motherboard  1100 . The motherboard  1100  can comprise a video signal switching unit  1000 . The video signal switching unit  1000  can comprise a video signal output unit  100 , a video interface  200 , a detecting unit  300 , a control unit  400 , a signal conversion unit  500 , a channel signal output unit  600 , and a channel signal transmission unit  800 . The video signal output unit  100  is electrically coupled to the video interface  200  and the signal conversion unit  500 . The video interface  200  is electrically coupled to the control unit  400  via the detecting unit  300 , and is electrically coupled to the channel signal output unit  600  via the channel signal transmission unit  800 . The control unit  400  is electrically coupled to the signal conversion unit  500  and the channel signal transmission unit  800 . The video signal output unit  100  is configured to output a first video signal. The channel signal output unit  600  is configured to output a first channel signal and a second channel signal. The detecting unit  300  is configured to detect the types of cables electrically coupled to the video interface  200 , and output the detected results in accordance with the detected types of cables to the control unit  400 . The control unit  400  is configured to control the signal conversion unit  500  to operate or not, and control the channel signal transmission unit  800  to transmit the first channel signal or the second channel signal, according to the detected results received from the detecting unit  300 . The signal conversion unit  500  is configured to convert the first video signal into a second video signal. 
         [0012]    In at least one embodiment, the video signal output unit  100  can be a central processing unit, the first video signal can be a DisplayPort video signal, and the second video signal can be a high definition multimedia interface (HDMI) video signal. The video interface  200  can be a DisplayPort. The channel signal output unit  600  can be a platform controller hub, the first channel signal can be a DisplayPort auxiliary channel signal DP AUX, and the second channel signal can be a HDMI display data channel signal HDMI DDC. 
         [0013]      FIGS. 2-4  illustrate an embodiment of the video signal switching unit  1000 . The control unit  400  can comprise three electronic switches Q 1 , Q 2 , and Q 11 , a capacitor C 1 , and eight resistors R 1 -R 3 , R 12 , R 13 , and R 26 -R 28 . Each of the electronic switches Q 1 , Q 2 , and Q 11  can comprise a first terminal, a second terminal, and a third terminal. The first terminal of the electronic switch Q 1  is electrically coupled to the detecting unit  300  through the resistor R 26 , electrically coupled to a ground through the capacitor C 1 , electrically coupled to a power supply V 3  through the resistor R 26  and the resistor R 27  in that order, and electrically coupled to the ground through the resistor R 26  and the resistor R 28  in that order. The second terminal of the electronic switch Q 1  is electrically coupled to a power supply V 1  through the resistor R 1 , and electrically coupled the ground through the second resistor R 2 . The third terminal of the electronic switch Q 1  is electrically coupled to the ground. The first terminal of the electronic switch Q 2  is electrically coupled to the second terminal of the electronic switch Q 1 . The second terminal of the electronic switch Q 2  is electrically coupled to a power supply V 2  through the resistor R 3 . The third terminal of the electronic switch Q 2  is electrically coupled to the ground. The first terminal of the electronic switch Q 11  is electrically coupled to the second terminal of the electronic switch Q 1 . The second terminal of the electronic switch Q 11  is electrically coupled to the power supply V 1  through the resistor R 12 , and electrically coupled to the ground through the resistor R 13 . The third terminal of the electronic switch Q 11  is electrically coupled to the ground. The second terminal of the electronic switch Q 2  functioning as a first output terminal O 1  of the control unit  400 , is electrically coupled to the signal conversion unit  500 . The second terminal of the electronic switch Q 11  functioning as a second output terminal O 2  of the control unit  400 , is electrically coupled to the channel signal transmission unit  800 . The second terminal of the electronic switch Q 1  functioning as a third output terminal O 3  of the control unit  400 , is electrically coupled to the channel signal transmission unit  800 . 
         [0014]    The video signal output unit  100  can comprise an interface  110 , and the interface  110  can comprise eight pins  1 - 8 . The video interface  200  can comprise ten pins  1 - 10 . The signal conversion unit  500  can comprise eight electronic switches Q 3 -Q 10  and eight resistors R 4 -R 11 . Each of the electronic switches Q 3 -Q 10  can comprise a first terminal, a second terminal, and a third terminal. The pins  1 - 8  of the interface  110  is electrically coupled to the pins  1 - 8  of the video interface  200 . Each first terminal of the electronic switches Q 3 -Q 10  is electrically coupled to the first output terminal O 1  of the control unit  400 . The second terminal of the electronic switch Q 3  is electrically coupled to the pin  1  of the interface  110  through the resistor R 4 . The second terminal of the electronic switch Q 4  is electrically coupled to the pin  2  of the interface  110  through the resistor R 5 . The second terminal of the electronic switch Q 5  is electrically coupled to the pin  3  of the interface  110  through the resistor R 6 . The second terminal of the electronic switch Q 6  is electrically coupled to the pin  4  of the interface  110  through the resistor R 7 . The second terminal of the electronic switch Q 7  is electrically coupled to the pin  5  of the interface  110  through the resistor R 8 . The second terminal of the electronic switch Q 8  is electrically coupled to the pin  6  of the interface  110  through the resistor R 9 . The second terminal of the electronic switch Q 9  is electrically coupled to the pin  7  of the interface  110  through the resistor R 10 . The second terminal of the electronic switch Q 10  is electrically coupled to the pin  8  of the interface  110  through the resistor R 11 . Each third terminal of the electronic switches Q 3 -Q 10  is electrically coupled to the ground. 
         [0015]    The channel signal output unit  600  can comprise two interfaces  610  and  620 . The interface  610  can comprise two pins  9  and  10 . The interface  620  can comprise two pins  11  and  12 . The channel signal transmission unit  800  can comprise ten electronic switches Q 12 -Q 21 , twelve resistors R 14 -R 25 , six diodes D 1 -D 6 , and two capacitors C 1  and C 2 . 
         [0016]    Each of the electronic switches Q 12 -Q 21  can comprise a first terminal, a second terminal, and a third terminal. Each first terminal of the electronic switches Q 12 -Q 15  is electrically coupled to the third output terminal O 3  of the control unit  400 . The second terminal of the electronic switch Q 12  is electrically coupled to the pin  9  of the interface  610 . The third terminal of the electronic switch Q 12  is electrically coupled to the ground through the resistor R 14 . The second terminal of the electronic switch Q 13  is electrically coupled to the pin  9  of the video interface  200 . The third terminal of the electronic switch Q 13  is electrically coupled to the third terminal of the electronic switch Q 12 . The second terminal of the electronic switch Q 14  is electrically coupled to the pin  10  of the interface  610 . The third terminal of the electronic switch Q 14  is electrically coupled to the ground through the resistor R 15 . The second terminal of the electronic switch Q 15  is electrically coupled to the pin  10  of the video interface  200 . The third terminal of the electronic switch Q 15  is electrically coupled to the third terminal of the electronic switch Q 14 . 
         [0017]    Each first terminal of the electronic switches Q 16 -Q 19  is electrically coupled to the second output terminal O 2  of the control unit  400 . The second terminal of the electronic switch Q 16  is electrically coupled to the pin  11  of the interface  620 . The third terminal of the electronic switch Q 16  is electrically coupled to the ground through the resistor R 16 . The second terminal of the electronic switch Q 17  is electrically coupled to the pin  9  of the video interface  200 . The third terminal of the electronic switch Q 17  is electrically coupled to the third terminal of the electronic switch Q 16 . The second terminal of the electronic switch Q 18  is electrically coupled to the pin  12  of the interface  620 . The third terminal of the electronic switch Q 18  is electrically coupled to the ground through the resistor R 17 . The second terminal of the electronic switch Q 19  is electrically coupled to the pin  10  of the video interface  200 . The third terminal of the electronic switch Q 19  is electrically coupled to the third terminal of the electronic switch Q 18 . 
         [0018]    The first terminal of the electronic switch Q 20  is electrically coupled to the second output terminal O 2  of the control unit  400 , and electrically coupled to the power supply V 2  through the resistor R 18 . The second terminal of the electronic switch Q 20  is electrically coupled to the pin  9  of the video interface  200  through the resistor R 19 , and is electrically coupled to the ground through the capacitor C 2 . The third terminal of the electronic switch Q 20  is electrically coupled to the pin  11  of the interface  620 , and is electrically coupled to the power supply V 2  through the resistor R 20 . The first terminal of electronic switch Q 21  is electrically coupled to the second output terminal O 2  of the control unit  400 , and electrically coupled to the power supply V 2  through the resistor R 21 . The second terminal of the electronic switch Q 21  is electrically coupled to the pin  10  of the video interface  200  through the resistor R 22 , and is electrically coupled to the ground through the capacitor C 3 . The third terminal of the electronic switch Q 21  is electrically coupled to the pin  12  of the interface  620 , and is electrically coupled to the power supply V 2  through the resistor R 23 . 
         [0019]    An anode of the diode D 1  is electrically coupled to the power supply V 3 . A cathode of the diode D 1  is electrically coupled to the second terminal of the electronic switch Q 20  through the resistor R 24 . An anode of the diode D 2  is electrically coupled to the ground. A cathode of the diode D 2  is electrically coupled to the second terminal of the electronic switch Q 20 . An anode of the diode D 3  is electrically coupled to the cathode of the diode D 2 . A cathode of the diode D 3  is electrically coupled to the power supply V 3 . An anode of the diode D 4  is electrically coupled to the power supply V 3 . A cathode of the diode D 4  is electrically coupled to the second terminal of the electronic switch Q 21  through the resistor R 25 . An anode of the diode D 5  is electrically coupled to the ground. A cathode of the diode D 5  is electrically coupled to the second terminal of the electronic switch Q 21 . An anode of the diode D 6  is electrically coupled to the cathode of the diode D 5 . A cathode of the diode D 6  is electrically coupled to the power supply V 3 . 
         [0020]    In operation, the video signal output unit  100  outputs the first video signal through the pins  1 - 8  of the interface  110 . The channel signal output unit  600  outputs the first channel signal through the pins  9  and  10  of the interface  610 , and outputs the second channel signal through the pins  11  and  12  of the interface  620 . The detecting unit  300  detects the type of cables electrically coupled to the video interface  200 , and outputs the detected result to the control unit  400 . 
         [0021]    When the detecting unit  300  detects that a first cable is electrically coupled to the video interface  200 , the detecting unit  300  outputs a low level signal, such as a logic 0 signal. The electronic switch Q 1  is turned off, and the electronic switches Q 2  and Q 11  are turned on. The first output terminal O 1  of the control unit  400  outputs a low level signal, such as a logic 0 signal, the second output terminal O 2  of the control unit  400  outputs a low level signal, such as a logic 0 signal, and the third output terminal O 3  of the control unit  400  outputs a high level signal, such as a logic 1 signal. 
         [0022]    When the first terminals of the electronic switches Q 3 -Q 11  receive the low level signal from the first output terminal O 1  of the control unit  400 , the electronic switches Q 3 -Q 11  are turned off, and the pins  1 - 8  of the video interface  200  receive the first video signal from the pins  1 - 8  of the interface  110 . 
         [0023]    When the first terminals of the electronic switches Q 12 -Q 15  receive the high level signal from the third output terminal O 3  of the control unit  400 , the electronic switches Q 12 -Q 15  are turned on. The first channel signal output from the pin  9  of the interface  610  is transmitted to the pin  9  of the video interface  200  through the electronic switches Q 12  and Q 13 , and first channel signal output from the pin  10  of the interface  610  is transmitted to the pin  10  of the video interface  200  through the electronic switches Q 14  and Q 15 . 
         [0024]    When the first terminals of the electronic switches Q 16 -Q 21  receive the low level signal from the second output terminal O 2  of the control unit  400 , the electronic switches Q 16 -Q 21  are turned off. The second channel signal output from the pins  11  and  12  of the interface  620  cannot be transmitted to the pins  9  and  10  of the video interface  200  through the electronic switches Q 16 -Q 21 . 
         [0025]    When the detecting unit  300  detects that a second cable is electrically coupled to the video interface  200 , the detecting unit  300  outputs a high level signal, such as a logic 1. The electronic switch Q 1  is turned on, and the electronic switches Q 2  and Q 11  are turned off. The first output terminal O 1  of the control unit  400  outputs a high level signal, such as a logic 1 signal, the second output terminal O 2  of the control unit  400  outputs a high level signal, such as a logic 1 signal, and the third output terminal O 3  of the control unit  400  outputs a low level signal, such as a logic 0 signal. 
         [0026]    When the first terminals of the electronic switches Q 3 -Q 11  receive the high level signal from the first output terminal O 1  of the control unit  400 , the electronic switches Q 3 -Q 11  are turned on. Voltages of the first video signal output from the pins  1 - 8  of the interface  110  are divided by the resistors R 4 -R 11 , therefore, the first video signal is converted into the second video signal by the signal conversion unit  500 , and the pins  1 - 8  of the video interface  200  receive the second video signal. 
         [0027]    When the first terminals of the electronic switches Q 16 -Q 21  receive the high level signal from the second output terminal O 2  of the control unit  400 , the electronic switches Q 16 -Q 21  are turned on. The second channel signal output from the pin  11  of the interface  620  is transmitted to the pin  9  of the video interface  200  through the electronic switches Q 16  and Q 17 , and is transmitted to the pin  9  of the video interface  200  through the electronic switch Q 20  and the resistor R 19 . The second channel signal output from the pin  12  of the interface  620  is transmitted to the pin  10  of the video interface  200  through the electronic switches Q 18  and Q 19 , and is transmitted to the pin  10  of the video interface  200  through the electronic switch Q 21  and the resistor R 22 . 
         [0028]    When the first terminals of the electronic switches Q 12 -Q 15  receive the low level signal from the third output terminal O 3  of the control unit  400 , the electronic switches Q 12 -Q 15  are turned off. The first channel signal output from the pins  9  and  10  of the interface  610  cannot be transmitted to the pins  9  and  10  of the video interface  200  through the electronic switches Q 12 -Q 15 . 
         [0029]    In at least one embodiment, each of the electronic switches Q 1 -Q 21  can be an re-channel metal-oxide semiconductor field-effect transistor (NMOSFET), and the first terminal, the second terminal, and the third terminal of each of the electronic switches Q 1 -Q 21  correspond to a gate, a drain, and a source of the NMOSFET, respectively. The first cable is a cable configured to transmit the DisplayPort video signal. The second cable is a cable configured to transmit the HDMI video signal. The power supply V 1  is a 19V power supply, the power supply V 2  is a 3V power supply, and the power supply V 3  is a 5V power supply. In other embodiments, each of the electronic switches Q 1  -Q 21  can be an npn-type bipolar junction transistor or other suitable switch having similar functions. 
         [0030]    The embodiment shown and described above is only an example. Many details are often found in the art such as the other features of the motherboard. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size and arrangement of the parts within the principles of the present disclosure up to, and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiment described above may be modified within the scope of the claims.