Abstract:
A rotatable display assembly is provided. The rotatable display assembly includes a base unit, a display unit and a wireless transmission system. The display unit is rotatably coupled to the base unit using at least one pivotal means, and the wireless transmission system is adapted to transmit data wirelessly between the base unit and the display unit.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to rotatable display assembly, and in particular, to a rotatable display assembly that can be used in electronic devices such as portable computers. 
     BACKGROUND OF THE INVENTION 
     A portable computer, such as a notebook, typically includes a variety of parts, such as motherboard, processor, hard disk, keyboard, power supply and display screen. The motherboard, processor, hard disk, power supply and the keyboard are usually housed in a main body. The display screen is housed in a display unit which is separate form the main body. The display unit is connected to the main body by a hinge which allows the display unit to be folded onto the main body, that is, in a fore and aft direction. 
     In some notebook models, such as a tablet PC, the display unit is connected to the main body by a swivel hinge so that the display unit can be rotated horizontally with respect to the main body. Thus, the display unit can be both folded in the fore and aft direction, and rotated horizontally. In this way, a user of the notebook may rotate the display unit to show the display screen to other people, or even fold the display unit onto the main body with the display screen facing outwards and away from the main body for presentation purposes. 
     In such a notebook with rotatable screen, cables run through the hinge from the main body to the display unit to supply power and to transmit data to the display screen. Due to the cables passing through the hinge, the hinge is constructed in a manner where the angle of rotation is restricted. In other words, the display unit cannot be rotated indefinitely in any given direction. Also, when the display unit is rotated in one direction, it has to be rotated back to its original position in the opposite direction. For example, if the display unit is rotated in the clockwise direction, it has to be rotated back to its original position in the anti-clockwise direction. This is because the cables through the hinge cannot be infinitely twisted. Furthermore, the frequent twisting of the cables when the display unit is being rotated may cause the cables to wear out or break. In addition, the cables through the hinge also occupy a significant amount of physical space. Therefore, the minimal size of the hinge is also restricted. 
     SUMMARY OF THE INVENTION 
     According to an embodiment, a rotatable display assembly is provided. The rotatable display assembly includes a base unit, a display unit and a wireless transmission system. The display unit is rotatably coupled to the base unit using at least one pivotal means, and the wireless transmission system is adapted to transmit data wirelessly between the base unit and the display unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of the invention will be better understood in view of the following drawings and the detailed description. 
         FIG. 1  shows an example of a table PC in which a rotatable display assembly according to an embodiment may be implemented. 
         FIG. 2  shows an interior of the tablet PC illustrating an example of an implementation of the rotatable display assembly according to an embodiment. 
         FIG. 3  shows an implementation of the rotatable display assembly according to another embodiment. 
         FIG. 4  a block diagram of a wireless transmission system according to an embodiment. 
         FIG. 5  a block diagram of the wireless transmission system according to another embodiment. 
         FIG. 6  shows an example of how electrical contacts may be made by power cables according to an embodiment. 
         FIG. 7  shows another example of an implementation of the rotatable display assembly according to another embodiment. 
         FIG. 8  shows an example of how electrical contacts may be made by power cables at pivoting means according to another embodiment. 
         FIG. 9  shows an example of an implementation of the rotatable display assembly using Bluetooth for transmitting data wirelessly according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiments described henceforth relate to a rotatable display assembly that can be used in electronic devices. Examples of electronic devices include portable computers (tablet PC, notebook) and mobile phones.  FIG. 1  shows an example of a tablet PC  100  in which the rotatable display assembly may be implemented. The tablet PC  100  includes a display unit  101  which houses a LCD screen  102 . The display unit  101  is connected to a base unit  103  using a hinge  110 . The display unit  101  can be moved in a fore and at direction, so that the display unit  101  is foldable onto a top surface of the base unit  103 . In addition, the display unit  101  can be rotated with respect to the base unit  103 , about an axis Y substantially perpendicular to a horizontal plane of the base unit  103 . 
     Data to be displayed on the LCD screen  102  are transmitted from a video graphic controller in the base unit  103  to the LCD screen  102  in the display unit  101 . According to an embodiment, data for display on the LCD screen  102  are transmitted wirelessly from the base unit  103  to the display unit  101 . Accordingly, the display unit  101  may be rotated about the axis Y in an unrestricted manner. In other words, the display unit  101  can have an unlimited angle of rotation with respect to the base unit  103 . 
       FIG. 2  shows an interior of the tablet PC  100  illustrating an implementation of the rotatable display assembly according to an embodiment. It should be noted that only components which illustrate the rotatable display assembly are shown in  FIG. 2 . Other components commonly found in tablet PCs, such as keyboard, I/O interfaces, CPU, memories, etc, are not included in the figure so as not to obscure the description of the rotatable display assembly. Also, the implementation of the rotatable display assembly shall not be limited to the tablet PC as shown in  FIG. 2 . It can also be implemented in other electronic devices such as a mobile phone, a portable DVD player or other devices having a rotatable screen. 
     The rotatable display assembly includes the display unit  101 , the base unit  103  and a wireless transmission system for transmitting data wirelessly from the base unit  103  to the display unit  101 . The display unit  101  is connected to the base unit  103  via a first hinge  111  and a second hinge  112 . The first hinge  111  allows the display unit  101  to move in the fore and aft direction. The second hinge  112  allows the display unit  101  to rotate with respect to the base unit  103 , about the axis Y. The second hinge  112  includes a first (upper) tubular structure  113  and a second (lower) tubular structure  114 . The first tubular structure  113  is attached to the display unit  101  and the second tubular structure  114  is attached to the base unit  103 . The first tubular structure  113  is rotatable with respect to the second tubular structure  114 . 
     It should be noted that the first and second hinges  111 ,  112  is only a general illustration of the hinge structures in order to describe the structure and operation of the rotatable display assembly. They do not represent the exact structure of hinges that is used in a tablet PC. Such hinge structures are known to one of ordinary skill in the art. The rotatable display assembly may also be implemented in electronic devices employing a variety of other hinge structures which allow the display unit  101  to rotate with respect to the base unit  103 . 
     The wireless transmission system includes a graphic controller  120 , transmitter circuitries  121 , an optical transmitter  122 , an optical receiver  123  and receiver circuitries  124 . The graphic controller  120 , transmitter circuitries  121  and the optical transmitter  122  are arranged in the base unit  103 . The optical receiver  123  and the receiver circuitries  124  are arranged in the display unit  101 . The optical transmitter  122  is arranged in the hollow space of the second tubular structure  114  and the optical receiver  123  is arranged in the hollow space of the first tubular structure  113 , such that both the optical transmitter and receiver  122 ,  123  are optically coupled to each other. In other words, both the optical transmitter and, receiver  122 ,  123  are in the line of sight to each other. Accordingly, data sent from the optical transmitter  122  in the form of modulated optical signal is received by the optical receiver  123 . 
     The optical transmitter  122  is electrically coupled to the transmitter circuitries  121 , which in turn is electrically coupled to the graphic controller  120 . The optical receiver  123  is electrically coupled to the receiver circuitries  124 , which in turn is electrically coupled to the LCD screen  102 . Accordingly, data output from the graphic controller in the base unit  103  is transmitted to the display unit  101  to be displayed on the LCD screen  102 . 
     It is also possible that the LCD screen  102  is touch-sensitive, so that a user may provide input to the tablet PC  100  by touching the LCD screen  102 . Therefore, data may also be transmitted from the display unit  101  to the base unit  103 . Such an implementation is illustrated in  FIG. 3 . With reference to  FIG. 3 , the wireless transmission system includes two transceiver modules  140 ,  141 , two transmitter circuitries  121 ,  143 , two receiver circuitries  124 ,  142  and the graphic controller  120 . 
     One of the optical transceivers  140  is arranged in the hollow space of the second tubular structure  114 . The optical transceiver  140  includes an optical transmitter and an optical receiver (not shown). The optical transmitter in the optical transceiver  140  is electrically coupled to the transmitter circuitries  121 , which in turn is electrically coupled to the graphic controller  120 . The optical receiver in the optical transceiver  140  is electrically coupled to the receiver circuitries  142 , which in turn may be electrically coupled to an I/O interface (not shown) for processing the input from the user. 
     The other optical transceiver  141  is arranged in the hollow space of the first tubular structure  113 . The optical transceiver  141  includes an optical transmitter and an optical receiver (not shown). The optical receiver in the optical transceiver  141  is electrically coupled to the receiver circuitries  124 , which in turn is electrically coupled to the LCD screen  102 . The optical transmitter in the optical transceiver  141  is electrically coupled to the transmitter circuitries  143 , which may in turn be electrically coupled to an interface of the LCD screen  102  to receive user input. Accordingly, data may be both transmitted from the base unit  103  to the display unit  101 , and from the display unit  101  to the base unit  103 . 
       FIG. 4  shows a block diagram of the wireless transmission system according to an embodiment. As already described with reference to  FIG. 2 , the wireless transmission system includes the graphic controller  120 , the transmitter circuitries  121 , the optical transmitter  122 , the optical receiver  123  and the receiver circuitries  124 . The transmitter circuitries  121  include encoder circuitries  201  and a laser driver  200 . The receiver circuitries  124  include decoder circuitries  203  and an amplifier  202 . 
     The graphic controller  120  (or VGA chip) outputs serial data to be displayed on the LCD screen  102 . An example of the output data is the DisplayPort output of a computer graphics engine. The output data is received by the encoder circuitries  201 . The encoder circuitries  201  encode the serial data from the graphic controller  120 . When there are more than one input sources to the encoder circuitries  201 , the encoder circuitries  201  may include a multiplexer to multiplex the various input data to form a single stream of data prior to encoding. The encoder circuitries  201  may also include error correction so that any data loss or error in the process of transmission can be corrected at a later decoding stage. 
     The encoded data from the encoder circuitries  201  is received by the laser driver  200 . The laser driver  200  modulates the encoded data into electrical pulses for controlling the optical transmitter  122 . The optical transmitter  122  includes a laser diode which emits a series of light pulses in response to the electrical pulses from the laser driver  200 . An example of the laser diode  122  is the Optoway DL-3100. The series of light pulses is received by the optical receiver  123  which is optically coupled to the laser diode  122 . The optical receiver  123  includes a photodiode which detects light incident on it. An example of the photodiode is the Optoway PD-1100. 
     The photodiode demodulates the received light pulses into electrical signal. The electrical signal is received by the amplifier  202 . The amplifier  202  amplifies the electrical signal. The amplifier  202  may include a transimpedance amplifier to covert the received electrical signal into corresponding voltage signal before amplifying it. The amplifier  202  may include a differential output compatible with DisplayPort signaling. The amplified signal is sent to the decoder circuitries  203  to be decoded. 
     If error correction was performed by the encoder circuitries  201 , the decoder circuitries  203  may perform data recovery for the amplified signal before decoding it. The decoded signal may be de-multiplexed by a de-multiplexer (if it was multiplexed at the encoder end) before it is sent to the LCD screen  102  to be displayed. 
       FIG. 5  shows a block diagram of the wireless transmission system according to another embodiment. The wireless transmission system shown in  FIG. 5  corresponds to the wireless transmission system as described above with reference to  FIG. 3  which includes the transceiver modules  140 ,  141 , the transmitter circuitries  121 ,  143 , the receiver circuitries  124 ,  142  and the graphic controller  120 . The transmitter circuitries  143  include encoder circuitries  211  and a laser driver  210 . The receiver circuitries  142  include decoder circuitries  213  and an amplifier  212 . 
     The decoder circuitries  213  are electrically coupled to the I/O interface  220 . The I/O interface  220  processes input data received from the touch-sensitive display  102 . The transceiver module  141  includes an optical transmitter  233  and the optical receiver  123 . Similarly, the transceiver module  140  includes the optical transmitter  122  and an optical receiver  232 . The descriptions and functions of each block are similar to those described in  FIG. 3  and  FIG. 4 , and will not be repeated here. 
     With reference to either  FIG. 2  or  FIG. 3  again, a power supply unit  130  supplies power to the display unit  101  through the second hinge  112 . In the example shown in  FIG. 2 , a pair of power cables  131  contacts the first tubular structure  113  to supply electrical power thereto. Another pair of power cables  132  also contacts the first tubular structure  113  and makes electrical contact with the pair of power cables  131  to supply electrical power to the display unit  101  specifically to the LCD screen  102 . 
       FIG. 6  shows an example of how electrical contacts may be made by the power cables according to an embodiment. In this example, the first tubular structure  113  includes a first conducting ring  301  and a second conducting ring  302 . One of the power cables  131  (Vcc) from the power supply unit  130  electrically contacts the first conducting ring  301 . The other power cable  131  (Ground) electrically contacts the second conducting ring  302 . Similarly, a corresponding Vcc power cable  132  from the display unit  101  electrically contacts the first conducting ring  301  and a corresponding Ground power cable  132  electrically contacts the second conducting ring  302 . Accordingly, power is supplied from the power supply unit  130  to the display unit  101  through the second hinge  112 . 
     Since the first tubular structure  113  is attached to the display unit  101  and does not rotate with respect to the display unit  101 , the power cables  132  do not need to move with respect to the first tubular structure  113 . Accordingly, the electrical contacts between the power cables  132  and the conducting rings  301 ,  302  may be formed, for example, by welding. As the first tubular structure  113  is rotatable with respect to the base unit  103 , it is also movable with respect to the power cables  131 . Accordingly, the power cables  131  may electrically contact the conducting rings  301 ,  302  using brush contacts. This allows the conducting rings  301 ,  302  to be slidable with respect to the power cables  131 , and still maintain electrical contacts. 
     It should be noted that other possible means of electrical contacts are possible as known to one of ordinary skill in the art. Also, power may also be supplied to the display unit  101  through the second tubular structure  114  instead of the first tubular structure  113  in another example. In such an example, the power cables  131  from the power supply unit  130  may be fixed to the conducting rings  301 ,  302  by welding, and the power cables  132  from the display unit  101  contacts the conducting rings  301 ,  302  using brush contacts. 
       FIG. 7  shows another example of an implementation of the rotatable display assembly according to another embodiment. The rotatable display assembly is implemented in a notebook having a display unit  401  which is rotatable with respect to a display frame  402 . The display unit  401  is supported by the display frame  402  by a first pivoting means  410  and a second pivoting means  411 , such that the display unit  401  is rotatable about an axis X. 
     Similar to the embodiment described with reference to  FIG. 2 , the rotatable display assembly includes the display unit  401 , a base unit  403  and a wireless transmission system for transmitting data wirelessly to the display unit  401 . The display unit  401  is connected to the display frame  402  via the two pivoting means  410 ,  411 . The display frame is in turn connected to the base unit  403  via a hinge  412 . The hinge  412  allows the display frame  402 , and hence the display unit  401 , to move in the fore and aft direction. The two pivoting means  410 ,  411  allow the display unit  401  to rotate with respect to the display frame  402 , about the axis X. 
     The first pivotal means  410  include a tubular structure  414  which is attached to the display unit  401 . The display frame  402  includes a corresponding hole or socket (not shown) for receiving the tubular structure  414 . Similarly, the second pivotal means  411  also include a tubular structure  413  attached to the display unit  401  and the display frame  402  includes another corresponding hole or socket (not shown) for receiving the tubular structure  413 . 
     The wireless transmission system includes a graphic controller  420 , transmitter circuitries  421 . an optical transmitter  422 , an optical receiver  423  and receiver circuitries  424 . The graphic controller  420 , transmitter circuitries  421  are arranged in the base unit  403 . The optical transmitter  422  is arranged in the display frame  402 . The optical receiver  423  and the receiver circuitries  424  are arranged in the display unit  401 . The optical transmitter  422  is arranged in the socket of the display frame  402  and the optical receiver  423  is arranged in the hollow space of the tubular structure  414 , such that both the optical transmitter and receiver  422 ,  423  are optically coupled to each other. Accordingly, data sent from the optical transmitter  422  in the form of modulated optical signal is received by the optical receiver  423 . 
     The optical transmitter  422  is electrically coupled to the transmitter circuitries  421 , which in turn is electrically coupled to the graphic controller  420 . The optical receiver  423  is electrically coupled to the receiver circuitries  424 , which in turn is electrically coupled to a LCD screen  404  in the display unit  401 . Accordingly, data output from the graphic controller in the base unit  403  is transmitted to the display unit  401  to be displayed on the LCD screen  402 . The descriptions and functions of the various components of the rotatable display assembly in this embodiment are similar to those described with reference to  FIGS. 2-5 , and will not be repeated here. 
       FIG. 8  shows an example of how electrical contacts may be made by the power cables  431 ,  432  at the pivoting means  410 ,  411  according to an embodiment. The tubular structure  413 ,  414  includes a conducting ring  501 . Both the power cables  431 ,  432  from the power supply unit  430  and the display unit  401  electrically contact the conducting ring  501 . In the example shown in  FIG. 8 , since the tubular structure  414  at the pivoting means  410  is attached to the display unit  401  and does not rotate with respect to the display unit  401 , the power cable  432  from the display unit  401  does not need to move with respect to the tubular structure  414 . Accordingly, the electrical contact between the power cables  432  and the conducting ring  501  may be formed, for example, by welding. As the tubular structure  414  is rotatable with respect to the display frame  402 , it is also movable with respect to the power cable  431  from the power supply unit  430 . Accordingly, the power cable  431  may electrically contact the conducting ring  501  using brush contacts. This allows the conducting ring  501  to be slidable with respect to the power cable  531  and still maintain electrical contacts. The same type of electrical contacts are used at the tubular structure  413  at the pivoting means  411 , to electrically connect the power cable  432  from the LCD screen  404  to the power cable  431  of the power supply unit  430 . 
     It should be noted that it is also possible for the tubular structures  413 ,  414  to be attached to the display frame  402  instead of to the display unit  401  in another example. In this example, the display unit  401  includes corresponding holes or sockets to receive the tubular structures  413 ,  414 . Accordingly, the power cable  431  from the power supply unit  430  may be fixed to the conducting ring  501  by welding, and the power cable  432  from the display unit  401  contacts the conducting ring  501  using brush contacts. Other types of implementing the pivotal means  410 ,  411  are also possible as known to one of ordinary skill in the art. 
     In the embodiments and examples described above, the wireless transmission system has been described using optical transmission means, specifically, using modulated light for transmitting data wirelessly. Other means of transmitting data wirelessly, for example transmission using Radio Frequency, is also possible according to other embodiments. 
       FIG. 9  shows an example of an implementation of the rotatable display assembly using Bluetooth for transmitting data wirelessly according to an embodiment. In this embodiment, the base unit  103  includes the graphic controller  120 , a first Bluetooth controller  601  and a first Bluetooth radio transceiver  602 . The display unit  101  includes the LCD screen  102 , a second Bluetooth controller  604  and a second BT radio transceiver  603 . 
     The graphics controller  120  is electrically coupled to the first Bluetooth controller  601 , and the first Bluetooth controller  601  is electrically coupled to the first Bluetooth radio transceiver  602 . The second Bluetooth radio transceiver  603  is electrically coupled to the second Bluetooth controller  604 , and the second Bluetooth controller  604  is electrically coupled to the LCD screen  102 . Accordingly, data is transmitted wirelessly between the two Bluetooth radio transceivers  602 ,  603 . Since Bluetooth employs Radio Frequency for data transmission, the two Bluetooth radio transceivers  602 ,  603  need not be arranged in line of sight to each other. They only need to be within certain distance from each other. 
     Although the present invention has been described in accordance with the embodiments as shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.