Abstract:
The present invention provides a wireless digital tablet with multiple transmission modes comprising a position detect unit, a transmission control unit, at least one wired connector, a wireless transmitter module, a wireless receiver module, a coder, and a decoder so that the wireless digital tablet transmit data to a computer at wired or wireless mode automatically according to whether the wired connector is connected in order to provide the selectivity of multiple transmission modes and save the consumption of the battery power of the wireless digital tablet.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a wireless digital tablet with multiple transmission modes, particularly to a wireless digital tablet comprising at least one wired connector, such that the wireless digital tablet changes to a wired or wireless transmission mode automatically according to whether a wired connector is connected, and as a result provides the selectivity of multiple transmission modes and save the consumption of the battery power of the wireless digital tablet.  
           [0003]    2. Description of the Prior Art  
           [0004]    Digital tablets with handwriting input are well known. Whereas the manner the well-known digital tablets transmit data is either by wirelessly connecting to a computer or through a wire. Wireless digital tablets are more convenient in use than wired ones, but without a power line they have to use a battery to drive their circuits. It is therefore an important subject to save the battery consumption in wireless digital tablets.  
           [0005]    Accordingly, a wireless digital tablet with both wired and wireless transmission modes contents both the need of wireless transmission mode where the user is limited to wire and space and the need of wired transmission mode to save the consumption of the battery power of the wireless digital tablet by being powered by the computer.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the background of the present invention described above, the object of the present invention is to provide a wireless digital tablet with multiple transmission modes, so as to connect to a computer at a wired or wirelessly mode.  
           [0007]    Another object of the present invention is to provide a wireless digital tablet with multiple transmission modes, such that when the wireless digital tablet connects with the computer at a wired mode, the computer powers the wireless digital tablet so as to save the consumption of the battery power of the wireless digital tablet.  
           [0008]    To achieve the objects described above, the present invention provides a wireless digital tablet with multiple transmission modes comprising a position detect unit, a transmission control unit, at least one wired connector, a wireless transmitter module, a wireless receiver module, a coder and a decoder so that the wireless tablet transmits data to a computer at a wired or wireless mode automatically according to whether the wired connector is connected in order to provide the selectivity of multiple transmission modes and save the consumption of the battery power of the wireless digital tablet.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 shows the circuit block diagram of the wireless digital tablet with multiple transmission modes provided in the present invention;  
         [0010]    [0010]FIG. 2 shows the flow chart for the detect loop of the transmission control unit;  
         [0011]    [0011]FIG. 3 shows the position-relative data signal before coding;  
         [0012]    [0012]FIG. 4 shows how the position-relative data signal coded by the coder; and  
         [0013]    [0013]FIG. 5 depicts the concrete structure of a preferred embodiment. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]    The preferred embodiments of the present invention will be described detailed as follows. Whereas, the present invention may be practiced extensively otherwise than the described herein, and as a result the present invention is not limited to the exact construction and operation illustrated and described herein and the scope of the present invention is within that of the claims hereafter.  
         [0015]    [0015]FIG. 1 shows the circuit block diagram of the wireless digital tablet with multiple transmission modes provided in the present invention, wherein the position detect unit  12  is used to detect the position of the induction pen, not shown, and produce a data signal relative to the position. The position detect unit  12  comprises an antenna loop, a transform circuit, and a process circuit. While the induction pen, not shown, is moving upon the digital tablet, the antenna loop of the position detect unit  12  induces an induced signal which is transformed to the corresponding digital signal by the transform circuit, whereby the process circuit processes the digital signal to obtain the position of the induction pen, and transmits the position-relative data signal to the transmission control unit  14  shown in FIG. 1. The position-relative data signal comprises an X-coordinate data signal, which is the position in X coordinate of the induction pen; a Y-coordinate data signal, which is the position in Y coordinate of the induction pen; a pressure signal, which indicates the pressure from the tip of the induction pen; and a button signal which indicates the status of the buttons on the induction pen.  
         [0016]    As shown in FIG. 1, the transmission control unit  14  connects with a coder  16  and a first wired connector  18  in addition to the position detect unit  12 . The transmission control unit  14  automatically determines whether to transmit the position-relative data signal to the coder  16  or the first wired connector  18  according to if the first wired connector  18  is connected. If the first wired connector  18  is not connected, the transmission control unit  14  direct transmits the position-relative data signal to the coder  16  to be coded; otherwise the transmission control unit  14  transforms the position-relative data signal to the corresponding format and sends it to the computer through the first wired connector  18 .  
         [0017]    The first wired connector  18  described above corresponds to the specification of Universal Serial Bus (USB), and the transmission control unit  14  detects whether the first wired connector  18  is connected using a well-known art. FIG. 2 shows the flow chart of the well-known art. As the digital tablet being actuated, the position detect unit  12  initializes various parameters, and runs into a detect loop. According to the well-known art, when the USB port on the computer  20  is connected, the computer  20  sends an interrupt signal to the device connected to the other end of the USB for notification of starting transmission. Hence in the detect loop the transmission control unit  14  decides to transmit the position-relative data signal to the coder  16  or the first wired connector  18  according to whether the computer  20  sends an interrupt signal and whether a data signal is to be transmitted. If the wireless digital tablet transmits the data signal to the computer  20  through the first wired connector  18 , the transmission control unit  14  switches the tablet to be powered by the computer  20  using a power supply pin contained in the USB, and therefore saves the consumption of the battery power of the tablet.  
         [0018]    If the first wired connector  18  is not connected, the transmission control unit  14  transmits the position-relative data signal to the coder  16  to be coded. FIG. 3 shows the position-relative data signal before coding, and FIG. 4 shows how the coder  16  codes the position-relative data signal, wherein X, Y, P, B represent the X-coordinate data signal, Y-coordinate data signal, pressure signal, and button signal respectively. X, Y, P comprise two bytes respectively, while B comprising only one byte, and each byte contains 7 bits of data signal. The coder  16  adds a byte of header code AF to the head of the position-relative data signal, and codes the first bit of each byte of X, Y, P, B to O, thus each byte of X, Y, P, B comprises a first bit coded O and following 7 bits of data signal. The coded position-relative data signal is transmitted to the wireless transmitter module  22  shown in FIG. 1, where a byte of synchronous signal A 5  is added ahead of each byte of the coded position-relative data signal, resulting in total 16 bytes in the final position-relative data signal; the wireless transmitter module  22  further adds a delay time between each byte of the position-relative data signal, and finally another delay time between adjacent position-relative data signals. The wireless transmitter module  22  and the wireless receiver module  24  shown in FIG. 1 correspond to the specification of RF or Blue Tooth format, and transmit the coded position-relative data signal using carrier modulation. As shown in FIG. 1, the wireless digital tablet further comprises a second wired connector  26  and a third wired connector  28 , the second wired connector  26  receiving the coded position-relative data signal from the coder while the third wired connector connecting with the second wired connector and sending the position-relative data signal to the computer through the wireless receiver module  24 , and the decoder  30 , such that when the first wired connector  18  is not connected and the second wired connector  26  and the third wired connector  28  are connected, the transmission control unit  14  determines automatically to transmit the coded position-relative data signal to the computer  20  through the second wired connector  26 , the third wired connector  28 , and the decoder  30 . The second wired connector  26  and the third wired connector  28  further comprise a power supply pin, such that when the second wired connector  26  and the third wired connector  28  are connected, the transmission control unit  14  switches the tablet to be powered by the computer  20 , and therefore saves the consumption of the battery power of the tablet. Accordingly the priority of the transmission modes in the preferred embodiment is as follows: if the first wired connector  18  is connected, then the position-relative data signal is transmitted to the computer  20  through the first wired connector  18 ; else if the second wired connector  26  and the third wired connector  28  are connected, the position-relative data signal is sent to the coder  16  and the wireless transmitter module  22  to be coded and then transmitted to the computer  20  through the second wired connector  26  and the third wired connector  28 ; else the position-relative data signal is sent to the coder  16  and the wireless transmitter module  22  to be coded and then wirelessly transmitted to the computer  20 . By way of the principle of the preferred embodiment, users may choose whether to use a wired connector to save the consumption of the battery power of the tablet.  
         [0019]    [0019]FIG. 5 shows a concrete structure of the former preferred embodiment. Another preferred embodiment of the wireless digital tablet with multiple transmission modes provided in the present invention may be practiced in a similar way as the former embodiment except that the first wired connector  18  is replaced with one corresponding to the specification of RS232. Because the power supplied by the RS232 pin is low, the first wired connector  18  herein has to come with an external power supply to maintain the tablet working. Similarly, the transmission control unit  14  switches the tablet to be powered by the external power supply, and therefore saves the consumption of the battery power of the tablet. In addition to USB and RS232, the first wired connector  18  may further be replaced with any other wired data transmission interface, for example, IEEE 1394 interface, as long as the wired data transmission interface contains a power supply pin or be equipped with an external power supply.  
         [0020]    Although the invention has been described and illustrated in detail as the preferred embodiments, it is to be clearly understood that the same is by way of illustration and example, and is not to be taken by way of limitation, and accordingly all variations and modifications in light of the spirit of the present invention are included within the scope of the following claims.