Patent Publication Number: US-2013241904-A1

Title: Driving circuit and data transmitting method thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a driving circuit and a data transmitting method; particularly, the present invention relates to a driving circuit and a data transmitting method used in a display device. 
     2. Description of the Related Art 
     The conventional display device includes a front-end circuit and a back-end circuit, wherein the front-end circuit processes digital data, and the back-end circuit converts the digital data into an analog data and transmit the analog data to the panel to display images. Generally, the operation voltage range of the digital data is between 2.5 V and 3.5 V, which is low voltage. However, the operation voltage range of the analog data is between 0 V and 15 V, which is high voltage. In practical applications, the conventional display device utilizes the back-end circuit to convert the digital data. 
     Please refer to  FIG. 1A ;  FIG. 1A  is a schematic view of the back-end circuit of the conventional display device. As shown in  FIG. 1A , a back-end circuit  10  includes a low voltage switch  11 A, a digital/analog conversion module  12 , an operational amplifier  13 , a high voltage switch  11 B, a first channel CH 1 , and a second channel CH 2 , wherein the digital/analog conversion module  12  includes a negative conversion unit  12 A and a positive conversion unit  12 B which are respectively disposed in the first channel CH 1  and the second channel CH 2 . 
     It is noted that the operation voltage range of the first digital data D 1  and the second digital data D 2  is around 3V to 3.3 V, and the first digital data D 1  and the second digital data D 2  are respectively transmitted in the first channel CH 1  and the second channel CH 2 . In practical applications, the first digital data D 1  and the second digital data D 2  are respectively transmitted to the digital/analog conversion module  12  by the low voltage switch  11 A, and the negative conversion unit  12 A and the positive conversion unit  12 B respectively convert the first digital data D 1  and the second digital data D 2  into the first negative analog data D 11  and the second positive analog data D 22 . The operational amplifier  13  respectively operates the first negative analog data D 11  and the second positive analog data D 22  in the first channel CH 1  and the second channel CH 2  and outputs the operated data to the high voltage switch  11 B. 
     Please refer to  FIG. 1B ;  FIG. 1B  is a schematic view of the back-end circuit of the conventional display device. As shown in  FIG. 1B , the first digital data D 1  and the second digital data D 2  are respectively transmitted in the first channel CH 1  and the second channel CH 2  and are switched to the second channel CH 2  and the first channel CH 1  by the low voltage switch  11 A. In addition, the second digital data D 2  and the first digital data D 1  are converted into the second negative analog data D 21  and the first positive analog data D 12  by the negative conversion unit  12 A and the positive conversion unit  12 B. It is noted that the second negative analog data D 21  and the first positive analog data D 12  are respectively transmitted to the operational amplifier  13  for operation. The operated second negative analog data D 21  and the first positive analog data D 12  are respectively transmitted to the high voltage switch  11 B. It is noted that the second negative analog data D 21  and the first positive analog data D 12  are respectively switched to the second channel CH 2  and the first channel CH 1  by the high voltage switch  11 B. 
     As shown in  FIGS. 1A and 1B , the end of the first channel CH 1  has a first negative analog data D 11  and a first positive analog data D 12 , and the end of the second channel CH 2  has a second positive analog data D 22  and a second negative analog data D 21 , so that the first channel CH 1  and the second channel CH 2  can operate the analog data. 
     In practical applications, when researchers and developers design the back-end circuit  10 , the low voltage switch  11 A and the high voltage switch  11 B have to be disposed in each channel to transmit the digital data or the analog data to the assigned channel. Particularly, the conventional display device utilizes the low voltage switch  11 A and the high voltage switch  11 B to switch the data respectively, so that each channel can operate corresponding positive analog data and negative analog data. It is desired to decrease the volume and the area of the conventional display device to produce small-size products. However, the low voltage switch  11 A and the high voltage switch  11 B have fixed volumes; it is hard to decrease the volume of the device effectively. 
     SUMMARY OF THE INVENTION 
     In view of prior arts, the present invention provides a driving circuit and a data transmitting method, which can decrease the cost and the volume effectively. 
     It is an object of the present invention to provide a data transmitting method, which utilizes different control signals to transmit digital data. 
     It is an object of the present invention to provide a driving circuit, which utilizes an operational amplifier to switch analog data. 
     It is an object of the present invention to provide a driving circuit, which decreases the amount of voltage switches to decrease the cost of material. 
     The present invention provides a driving circuit including a plurality of channels, at least one digital/analog conversion module, and at least one operational amplifier. The channels include a first channel and a second channel, wherein a first digital data and a second digital data are selectively transmitted to the first channel or the second channel according to an input control signal. 
     In practical applications, each digital/analog conversion module includes a negative conversion unit and a positive conversion unit, and the negative conversion unit and the positive conversion unit are respectively coupled with the first channel and the second channel, so that the first digital data and the second digital data are selectively transmitted to the negative conversion unit or the positive conversion unit to be converted into a negative analog data or a positive analog data; and 
     In addition, each operational amplifier is coupled with the digital/analog conversion module and has a switching unit, wherein the negative analog data and the positive analog data, according to a switching control signal, are selectively transmitted from the first channel or the second channel to the other channel through the switching unit. 
     The present invention provides a data transmitting method including: according to an input control signal, selectively transmitting a plurality digital data to a plurality of channels, wherein the channels include a first channel and a second channel, and the first channel and the second channel respectively have a negative conversion unit and a positive conversion unit; by means of the negative conversion unit or the positive conversion unit converting the digital data into a plurality of negative analog data or a plurality of positive analog data; and according to a switching control signal, by means of a switching unit selectively switching the negative analog data or the positive analog data from its corresponding channel to another channel. 
     In other words, the present invention utilizes the input control signal to control the transmission of the digital data to the first channel or the second channel and to control the transmission of the analog data to the first channel or the second channel by the operational amplifier, further operating the analog data in the first channel and the second channel. 
     Compared to prior arts, the driving circuit and the data transmitting method of the present invention control the transmission of the digital data to the assigned channel according to the input control signal, utilize the switching unit transmitting the analog data to the original channel or another channel according to the switching control signal to operate the analog data. It is noted that the embodiments of the present invention only utilize the control signals having different control timings and the switching unit to decrease the cost and the area of the chip effectively. 
     The detailed descriptions and the drawings thereof below provide further understanding about the advantage and the spirit of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1A  is a schematic view of the back-end circuit of the conventional display device; 
         FIG. 1B  is a schematic view of the back-end circuit of the conventional display device; 
         FIG. 2A  is a schematic view of the embodiment of the driving circuit in the first control timing of the present invention; 
         FIG. 2B  is a schematic view of the embodiment of the driving circuit in the second control timing of the present invention; 
         FIG. 3  is a flow chart of the data transmitting method; 
         FIG. 4A  is a flow chart of the data transmitting method for the first digital data of the present invention; 
         FIG. 4B  is a flow chart of the data transmitting method for the second digital data of the present invention; and 
         FIG. 5  is a flow chart of the data transmitting method of different control timings of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment of the present invention, a driving circuit is provided to control a plurality of digital data. In the embodiment, the driving circuit is used in an LCD device to drive an LCD panel, but is not limited to the embodiment. In other embodiments, the driving circuit can be used in any type of display device, such as plasma display device or laser display device, and is not limited to the embodiment. In practical applications, the driving circuit can be a source driver circuit of the display panel, but is not limited to the embodiment. In the embodiment, the front-end circuit of the display device has a plurality of even number channels and a plurality of odd number channels, wherein the even number channels and the odd number channels are connected with the source driver circuit of the display panel, so that digital data in the channels is switched by the source driver circuit and is converted into analog data. In other words, the driving circuit is the back-end circuit of the display panel and is used to output the analog data to the display panel to output images. 
     Please refer to  FIG. 2A ;  FIG. 2A  is a schematic view of the embodiment of the driving circuit in the first control timing of the present invention. Particularly,  FIG. 2A  is a schematic view of the driving circuit  1  operating a plurality of digital data in the first control timing. As shown in  FIG. 2A , the driving circuit  1  includes a plurality of channels  20 , at least one digital/analog conversion module  30 , at least one operational amplifier  40 , and a control module  50 . It is noted that the channels  20  can be any type of channels, and the digital/analog conversion module  30  can be any type of digital/analog converter and not limited to the embodiment. It is noted that the control module  50  generates a plurality of control signals having different control timings, wherein the control signals include an input control signal  510  and a switching control signal  520 . In other words, the control module  50  generates the control signals according to the practical use of the circuit  1 , but is not limited to the embodiment. 
     In the embodiment, the channels  20  include a first channel  210  and a second channel  220 , wherein a first digital data D 1  and a second digital data D 2  are selectively transmitted to the first channel  210  or the second channel  220  according to the input control signal  510 . As shown in  FIG. 2A , each digital/analog conversion module  30  includes a negative conversion unit  310  and a positive conversion unit  320 , wherein the negative conversion unit  310  and the positive conversion unit  320  are respectively coupled with the first channel  210  and the second channel  220 , so that the first digital data D 1  and the second digital data D 2  are selectively transmitted to the negative conversion unit  310  or the positive conversion unit  320  to be converted into a negative analog data or a positive analog data. 
     It is noted that the embodiment utilizes two channels  210 / 220  and two digital signals D 1 /D 2  to illustrate the present invention, but the amount of channels  20  and the amount of digital data of the driving circuit  1  are not limited to the embodiment. It is noted that the digital data and the analog data are transmitted in the driving circuit  1  in form of voltage, wherein a voltage of the digital data is between 2.5 V and 3.5 V, a voltage of the negative analog data is between 0 V and 7.5 V, and a voltage of the positive analog data is between 7.5 V and 15 V, but not limited to the embodiment. In other words, the negative conversion unit  310  converts the digital data into an analog data with a medium/high voltage; the positive conversion unit  320  converts the digital data into an analog data with a high voltage. In practical applications, low voltage (e.g. 3 V) cannot drive the display panel, so the driving circuit  1  utilizes the medium/high voltage or high voltage (e.g. 7.5 V) to drive the display panel. In the embodiment, the negative conversion unit  310  and the positive conversion unit  320  are level shifters and can convert the voltage of the digital data, but not limited to the embodiment. 
     In general, the driving circuit  1  transmits the first digital data D 1  (or the second digital data D 2 ) in its channel  20  to output the analog data having the medium/high voltage and the analog data having the high voltage, so that the driving circuit  1  operates corresponding analog data in the same channel. As shown in  FIG. 2A , each operational amplifier  40  is coupled with the digital/analog conversion module  30  and has a switching unit  410 , wherein the negative analog data and the positive analog data, according to a switching control signal  520 , are selectively transmitted from the first channel  210  or the second channel  220  to the other channel through the switching unit  520 . 
     For instance, the first digital data D 1  is transmitted to the first channel  210  according to a first control timing of the input control signal  510  and is converted to a first negative analog data D 11  by the negative conversion unit  310 . In addition, please refer to  FIG. 2B ;  FIG. 2B  is a schematic view of the embodiment of the driving circuit in the second control timing of the present invention. Particularly,  FIG. 2B  is a schematic view of the driving circuit  1  operating the digital data in the second control timing. As shown in  FIG. 2B , the first digital data D 1  is transmitted to the second channel  220  according to the second control timing of the input control signal  510  and is converted into a first positive analog data D 12  by the positive conversion unit  320 . The first positive analog data D 12  is transmitted to the first channel  210  according to the switching control signal  520 , so that the first negative analog data D 11  and the first positive analog data D 12  are operated in the first channel  210 . Particularly, the driving circuit  1  compares the first negative analog data D 11  with the first positive analog data D 12  in the first channel  210  and outputs the compared result to the display panel. 
     As shown in  FIG. 2A , for the second digital data D 2 , the second digital data D 2  is transmitted to the second channel  220  according to the first control timing of the input control signal  510  and is converted into the second positive analog data D 22  by the positive conversion unit  320 . Please refer to  FIG. 2B , the second digital data D 2  is transmitted to the first channel  210  according to the second control timing of the input control signal  510  and is converted into the second negative analog data D 21  by the negative conversion unit  310 . The second negative analog data D 21  is transmitted to the second channel  220  according to the switching control signal  520 , so that the second negative analog data D 21  and the second positive analog data D 22  are operated in the second channel  220 . Particularly, the driving circuit  1  compares the second negative analog data D 21  with the second positive analog data D 22  in the second channel  220  and outputs the compared result to the display panel. 
     Hence, the present invention utilizes the input control signal  510 , the switching control signal  520 , and the switching unit  410  to switch the digital data and the analog data rather than disposing the low voltage switch and the high voltage switch, further decreasing the cost of material and the area of the chip. 
     In addition to the embodiment of the driving circuit  1 , the present invention provides a data transmitting method to illustrate the practical operation steps. 
     According to another embodiment of the present invention, a data transmitting method is provided to transmit a plurality of digital data and a plurality of analog data. 
     Please refer to  FIG. 3 ;  FIG. 3  is a flow chart of the data transmitting method. The data transmitting method includes the step  101 : generating a plurality of control signals having different control timings, wherein the control signals include an input control signal and a switching control signal, and the control timings include a first control timing and a second control timing. For instance, as shown in  FIGS. 2A and 2B , the control module  50  respectively generates the input control signals  510  having the first control timing and the second control timing and the switching control signal  520 . 
     The step  103  involves according to the input control signal, selectively transmitting a plurality digital data to a plurality of channels, wherein the channels include a first channel and a second channel. The first channel and the second channel have a negative conversion unit and a positive conversion unit, respectively. As shown in  FIG. 2A , the first digital data D 1  and the second digital data D 2  are respectively transmitted to the first channel  210  and the second channel  220  according to input control signal  510 . As shown in  FIG. 2B , the second digital data D 2  and the first digital data D 1  are respectively transmitted to the first channel  210  and the second channel  220  according to input control signal  510 . 
     The step  105  includes, by means of the negative conversion unit or the positive conversion unit converting the digital data into a plurality of negative analog data or a plurality of positive analog data. It is noted that a voltage of the digital data is between 2.5 V and 3.5 V, a voltage of the negative analog data is between 0 V and 7.5 V, and a voltage of the positive analog data is between 7.5 V and 15 V, but not limited to the embodiment. For instance, as shown in  FIG. 2A , the digital data D 1  is converted into the first negative analog data D 11  by the negative conversion unit  310 ; the second digital data D 2  is converted into the second positive analog data D 22  by the positive conversion unit  320 . 
     The step  107  includes, according to the switching control signal, by means of a switching unit selectively switching the negative analog data or the positive analog data from its corresponding channel to another channel. For instance, as shown in  FIG. 2B , the second negative analog data D 21  is transmitted from the first channel  210  to the second channel  220  through the switching unit  410  according to the switching control signal  520 . 
     In the embodiment, the digital data of the step  103  in  FIG. 3  includes the first digital data and the second digital data. Please refer to  FIG. 4A ;  FIG. 4A  is a flow chart of the data transmitting method for the first digital data of the present invention. As shown in  FIG. 4A , the method further includes the step  201 A: according to the first control timing of the input control signal, transmitting the first digital data to the first channel and by means of the negative conversion unit converting the first digital data into a first negative analog data. The step  203 A involves according to the second control timing of the input control signal, transmitting the first digital data to the second channel and by means of the positive conversion unit converting the first digital data into a first positive analog data. The step  205 A involves according to the switching control signal, transmitting the first positive analog data to the first channel. The step  207 A involves operating the first negative analog data and the first positive analog data in the first channel. 
     In addition, please refer to  FIG. 4B ;  FIG. 4B  is a flow chart of the data transmitting method for the second digital data of the present invention. As shown in  FIG. 4B , the method further includes the step  201 B, according to the first control timing of the input control signal, transmitting the second digital data to the second channel and by means of the positive conversion unit converting the second digital data into a second positive analog data. The step  203 B involves according to the second control timing of the input control signal, transmitting the second digital data to the first channel and by means of the negative conversion unit converting the second digital data into a second negative analog data. The step  205 B involves according to the switching control signal, transmitting the second negative analog data into the second channel. The step  207 B involves operating the second negative analog data and the second positive analog data in the second channel. 
     Please refer to  FIG. 5 ;  FIG. 5  is a flow chart of the data transmitting method of different control timings of the present invention. As shown in  FIG. 5 , the method includes the step  301 , according to the first control timing of the input control signal, respectively transmitting the first digital data and the second digital data to the first channel and the second channel. The step  303  involves respectively by means of the negative conversion unit and the positive conversion unit converting the first digital data and the second digital data into a first negative analog data and a second positive analog data. The step  305  involves according to the switching control signal, respectively transmitting the first negative analog data and the second positive analog data to the first channel and the second channel. The step  307  involves according to the second control timing of the input control signal, respectively transmitting the first digital data and the second digital data to the second channel and the first channel. The step  309  involves respectively by means of the negative conversion unit and the positive conversion unit converting the second digital data and the first digital into a second negative analog data and a first positive analog data. The step  311  involves according to the switching control signal, respectively transmitting the second negative analog data and the first positive analog data to the second channel and the first channel. The step  313 A involves operating the first negative analog data and the first positive analog data in the first channel. The step  313 B involves operating the second negative analog data and the second positive analog data in the second channel. 
     It is noted that, in the flow chart of  FIG. 5 , the steps  301  to  305  can be executed between the steps  311  and  313 . In other words, the steps  301  to  305  are executed according to the first control timing, and the steps  307  to  311  are executed according to the second control timing, wherein the order of the first control timing and the second control timing of the method is not limited to the embodiment. 
     Compared to prior arts, the driving circuit  1  and the data transmitting method of the present invention control the transmission of the digital data to the assigned channel  20  according to the input control signal  510  and also utilize the switching unit  410  transmitting the analog data to the original channel  20  or the other channel  20  according to the switching control signal  520  to operate the analog data. It is noted that the embodiments of the present invention only utilize the control module generating the control signals having different control timings and the switching unit  410 , eliminating the use of low and high voltage switches and further decreasing the cost and the area of the chip. 
     Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.