Patent Publication Number: US-2013241648-A1

Title: Driving circuit, operational amplifier, and data transmitting method thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a driving circuit, an operational amplifier, and a data transmitting method; particularly, the present invention relates to a driving circuit, an operational amplifier, and a data transmitting method used in a display device. 
     2. Description of the Related Art 
     In general, 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 analog data and transmits 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 LCD device. As shown in  FIG. 1A , a back-end circuit  111  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 LCD 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 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, an operational amplifier, and a data transmitting method, which can effectively decrease the cost and the volume. 
     It is an object of the present invention to provide an operational amplifier, which compares the voltages and has high impedance. 
     It is an object of the present invention to provide a driving circuit, which decreases the amount of the voltage switches to decrease the cost of materials. 
     It is an object of the present invention to provide a data transmitting method, which utilizes control signals to control the analog data. 
     According to an embodiment of the present invention, an operational amplifier is provided, wherein the operational amplifier is connected to a channel. The operational amplifier includes a coupling end, a positive switch, a negative switch, and an output end, wherein the coupling end coupled with a first node and a second node, and an analog data is transmitted from the coupling end to the first node and the second node. The positive switch includes a positive control unit and a positive switch unit, and the first node is coupled with the coupling end and the positive switch unit, wherein the positive control unit is connected to the first node. In addition, the negative switch includes a negative control unit and a negative switch unit, wherein the second node is coupled with the coupling end and the negative switch unit, and the negative control unit is connected to the second node. The output end is coupled between the negative switch unit and the positive switch unit. The positive control unit and the negative control unit, respectively according to a positive control signal and a negative control signal, selectively activate or deactivate the positive switch unit and the negative switch unit to control transmission of the analog data to the output end. 
     According to another embodiment of the present invention, a driving circuit is provided. The driving circuit includes a plurality of channels and a plurality of operational amplifiers, wherein one of the operational amplifiers is coupled with one of the channels. The operational amplifier includes a coupling end, a positive switch, a negative switch, and an output end, wherein the coupling end is coupled with a first node and a second node, and an analog data is transmitted from the coupling end to the first node and the second node. The positive switch includes a positive control unit and a positive switch unit, wherein the first node is coupled with the coupling end and the positive switch unit, and the positive control unit is connected to the first node. It is noted that the negative switch includes a negative control unit and a negative switch unit, the second node is coupled with the coupling end and the negative switch unit, and the negative control unit is connected to the second node. The output end is coupled between the negative switch unit and the positive switch unit, wherein the positive control unit and the negative control unit, respectively according to a positive control signal and a negative control signal, selectively activate or deactivate the positive switch unit and the negative switch unit to control transmission of the analog data to the output end. 
     According to another embodiment of the present invention, a data transmitting method is provided for an operational amplifier, wherein the operational amplifier is coupled with a channel and includes a positive switch, a negative switch, and a coupling end. The coupling end is coupled with a first node and a second node. The positive switch includes a positive control unit and a positive switch unit. The first node is coupled with the coupling end and the positive switch unit. The positive control unit is connected to the first node. The negative switch includes a negative control unit and a negative switch unit. The second node is coupled with the coupling end and the negative switch unit. The negative control unit is connected to the second node. The data transmitting method includes: transmitting an analog data to the first node and the second node from the coupling end; and by the positive control unit and the negative control unit, respectively according to a positive control signal and a negative control signal, selectively activating or deactivating the positive switch unit and the negative switch unit to control transmission of the analog data to an output end, wherein the output end is coupled between the negative switch unit and the positive switch unit. 
     Compared to prior arts, the driving circuit, the operational amplifier, and the data transmitting method of the present invention respectively control the positive control unit and the negative control unit of the operational amplifier according to the positive control signal and the negative control signal, so that the positive switch unit and the negative switch unit can control whether the analog data is transmitted to the output end or not, further achieving the effect of the conventional high voltage switch. Hence, the embodiments of the present invention only utilize operational amplifiers of different design to control the analog data, eliminating the use of high voltage switches of the conventional display device and further decreasing the cost and the area of the chip. 
     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 LCD device; 
         FIG. 1B  is a schematic view of the back-end circuit of the conventional LCD device; 
         FIG. 2  is a schematic view of the embodiment of an operational amplifier of the present invention; 
         FIG. 3  is a schematic view of another embodiment of the operational amplifier of the present invention; 
         FIG. 4  is a schematic view of the embodiment of the driving circuit of the present invention; 
         FIG. 5  is a flow chart of a data transmitting method of the present invention; and 
         FIG. 6  is a flow chart of the data transmitting method of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment of the present invention, an operational amplifier is provided. In the embodiment, the operational amplifier is used in a driving circuit, especially a source driver circuit of an LCD device, but is not limited to the embodiment. 
     Please refer to  FIG. 2 ;  FIG. 2  is a schematic view of the embodiment of an operational amplifier of the present invention. As shown in  FIG. 2 , an operational amplifier  20  is connected to a channel  10  and includes a coupling end  30 , a positive switch  40 , a negative switch  50 , and an output end  60 , wherein the coupling end  30  is coupled with a first node  310  and a second node  320 . It is noted that the channel  10  can be any type of circuit channel and not limited to the embodiment. In the embodiment, the difference between the positive switch  40  and the negative switch  50  is amplitude of the working voltage. For instance, the voltage of the positive switch  40  approaches the operating voltage of the operational amplifier, and the voltage of the negative switch  50  approaches zero potential. However, in other embodiments, the voltage of the positive switch  40  and the negative switch  50  can be controlled by the driving circuit, but not limited to the embodiment. 
     It is noted that the positive switch  40  includes a positive control unit  410  and a positive switch unit  420 , wherein the first node  310  is coupled with the coupling end  30  and the positive switch unit  420 , and the positive control unit  410  is connected to the first node  310 . In addition, the negative switch  50  includes a negative control unit  510  and a negative switch unit  520 , wherein the second node  320  is coupled with the coupling end  30  and the negative switch unit  520 , and the negative control unit  510  is connected to the second node  320 . 
     It is noted that the output end  60  is coupled between the negative switch unit  520  and the positive switch unit  420 , wherein the positive control unit  410  and the negative control unit  420 , respectively according to a positive control signal S 1  and a negative control signal S 2 , selectively activate or deactivate the positive switch unit  420  and the negative switch unit  520  to control transmission of the analog data  100  to the output end  60 . 
     Particularly, the present invention utilizes the positive control signal S 1  and the negative control signal S 2  to respectively control the positive control unit  410  and the negative control unit  420 , and the positive control unit  410  and the negative control unit  420  respectively output an operated result, so that the positive switch unit  420  and the negative switch unit  520  is driven to be activated or to be deactivated according to the operated result, further determining whether the analog data is transmitted to the output end or not. In other words, the positive control unit  410  and the negative control unit  510  can be any type of control logic circuit, and the positive switch unit  420  and the negative switch unit  520  can be any type of switch component. For instance, the positive control unit  410 A, the positive switch unit  420 A, the negative control unit  510 A, and the negative switch unit  520 A can be transistors or other circuit components, not limited to the embodiment. 
     Please refer to  FIG. 3 ;  FIG. 3  is a schematic view of another embodiment of the operational amplifier of the present invention. As shown in  FIG. 3 , the operational amplifier  20 A includes the positive switch  40 A and the negative switch  40 B. The positive switch  40 A has a positive control unit  410 A and a positive switch unit  420 A. The negative switch  50 A has a negative control unit  510 A and the negative switch unit  520 A. In the embodiment, the positive control unit  410 A, the positive switch unit  420 A, the negative control unit  510 A, and the negative switch unit  520 A are transistors. The present invention utilizes the operating voltage of the positive control unit  410 A and the negative control unit  510 A and selectively outputs the voltage to the positive switch unit  420 A and the negative switch unit  520 A to control the transmission of the analog data, either for data transmission or stopping the data transmission. 
     In practical applications, the positive control unit  410 A and the negative control unit  510 A respectively output a positive control voltage  400 A and a negative control voltage  500 A to the positive switch unit  420 A and the negative switch unit  520 A according to the positive control signal S 1  and the negative control signal S 2 . It is noted that the positive switch unit  420 A and the negative switch unit  520 A respectively have a positive switch voltage  400 B corresponding to the positive control voltage  400 A and a negative switch voltage  500 B corresponding to the negative control voltage  500 A, so that the positive switch unit  420 A and the negative switch unit  520 A are controlled to stop transmitting the analog data  100  to the output end  60 . 
     It is noted that the operational amplifier  20 A has the operating voltage. For instance, the range of the operating voltage can be between 0 V and 15 V, but not limited to the embodiment. In the embodiment, the operating voltages of the operational amplifier  20 A, the positive control voltage  400 A, and the positive switch voltage  400 B are identical. In addition, the negative control voltage  500 A and the negative switch voltage  500 B are zero potential. In the embodiment, the negative control unit  510 A and the negative switch unit  520 A are connected to the ground, so that the negative control voltage  500 A and the negative switch voltage  500 B are zero potential. 
     In practical applications, the positive switch unit  420 A utilizes the positive control voltage  400 A and the positive switch voltage  400 B, which are identical, as well as the negative control voltage  500 A and the negative switch voltage  500 B, which are identical, to generate open circuit between the positive switch unit  420 A and the negative switch unit  520 A. In other words, when the positive switch unit  420 A and the negative switch unit  520 A respectively receive the positive control voltage  400 A and the negative control voltage  500 A from the positive control unit  410 A and the negative control unit  510 A, the positive switch unit  420 A and the negative switch unit  520 A are at open circuit state, so that the transmission of the analog data  100  to the output end  60  is stopped. 
     Relatively, the positive control unit  410 A and the negative control unit  510 A stop outputting the positive control voltage  400 A and the negative control voltage  500 A to the positive switch unit  420 A and the negative switch unit  520 A according to the positive control signal S 1  and the negative control signal S 2 , so that the positive switch unit  420 A and the negative switch unit  520 A are controlled to transmit the analog data  100  to the output end  60 . 
     In other words, when the positive switch unit  420 A and the negative switch unit  520 A respectively stop receiving the positive control voltage  400 A and the negative control voltage  500 A from the positive control unit  410 A and the negative control unit  510 A, the positive switch unit  420 A and the negative switch unit  520 A are at conducting state, so that the analog data  100  is transmitted to the output end  60 . 
     Hence, the operational amplifier  20 A of the present invention utilizes the positive control signal S 1  and the negative control signal S 2  to control the positive switch  40 A and the negative switch  50 A to determine whether the analog data  100  is transmitted to the output end  60  or not. 
     According to another embodiment of the present invention, a driving circuit is provided. In the embodiment, the driving circuit is used in an LCD device to drive an LCD panel, but not limited to the embodiment. In other embodiments, the driving circuit can be used in any type of display device, such as plasma display devices, laser display devices, or other display devices, and not limited 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. 4 ;  FIG. 4  is a schematic view of the embodiment of the driving circuit  1  of the present invention. As shown in  FIG. 4 , the driving circuit  1  includes a plurality of channels  10 , a plurality of operational amplifiers  20 B, and a plurality of digital/analog conversion modules. The operational amplifiers  20 B are coupled with corresponding channels  10 . Each digital/analog conversion module  70  is connected to the operational amplifier  20 B by the channel  10 , and the digital data is converted into the analog data by the digital/analog conversion module  70  and then transmitted to the operational amplifier  20 B. 
     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 analog data is between 0 V and 15 V, but not limited to the embodiment. In other words, the digital/analog conversion module  70  converts the digital data into an analog data as an analog voltage. In practical applications, low voltage (e.g. 3 V) cannot drive the display panel, so the driving circuit  1  utilizes the analog voltage (e.g. 7.5 V) to drive the display panel. In the embodiment, the digital/analog conversion module  70  is a level shifter and can convert the voltage of the digital data, but not limited to the embodiment. 
     With regard to detailed descriptions of the circuit configuration of the operational amplifier  20 B, in addition to the circuit components of the operational amplifier  20  in  FIG. 2 , an operating unit  200  is further included. In the embodiment, the operating unit  200  operates and amplifies the analog data, and transmits the analog data to the first node  310  and the second node  320  through the coupling end  30 . In addition, the operational amplifier  20 B controls the positive switch  40  and the negative switch  50  to transmit or to stop transmitting the analog data to the output end  60 . In practical applications, the analog data is transmitted to the display panel to output images on the display panel. 
     In addition to the embodiment of the driving circuit  1 , a data transmitting method of the present invention is provided to illustrate the practical operating steps. 
     According to another embodiment of the present invention, a data transmitting method is provided to illustrate steps of transmitting the analog data. 
     It is noted that the data transmitting method is used in an operational amplifier, wherein the operational amplifier is coupled with a channel and includes a positive switch, a negative switch, and a coupling end. The coupling end is coupled with a first node and a second node. The positive switch includes a positive control unit and a positive switch unit. The first node is coupled with the coupling end and the positive switch unit. The positive control unit is connected to the first node. The negative switch includes a negative control unit and a negative switch unit. The second node is coupled with the coupling end and the negative switch unit. The negative control unit is connected to the second node. 
     Please refer to  FIG. 5 ;  FIG. 5  is a flow chart of a data transmitting method of the present invention. Firstly, the data transmitting method executes the step  101 : transmitting an analog data to the first node and the second node from the coupling end. For instance, as shown in  FIG. 2 , the analog data  100  is transmitted to the first node  310  and the second node  320  from the coupling end  30 . 
     In addition, the data transmitting method executes the step  103 : by the positive control unit and the negative control unit, respectively according to a positive control signal and a negative control signal, selectively activating or deactivating the positive switch unit and the negative switch unit to control transmission of the analog data to an output end, wherein the output end is coupled between the negative switch unit and the positive switch unit. As shown in  FIG. 2 , the positive control unit  410  and the negative control unit  510 , respectively according to the positive control signal S 1  and the negative control signal S 2 , selectively activate or deactivate the positive switch unit  420  and the negative switch unit  520  to control transmission of the analog data  100  to the output end  60 . 
     In addition, in the flow chart of  FIG. 5 , the positive control unit and the negative control unit respectively have a positive control voltage and a negative control voltage. The positive switch unit and the negative switch unit respectively have a positive switch voltage corresponding to the positive control voltage and a negative switch voltage corresponding to the negative control voltage. In addition, the positive control voltage and the positive switch voltage are identical. The negative control voltage and the negative switch voltage are zero potential. 
     Please refer to  FIG. 6 ;  FIG. 6  is a flow chart of the data transmitting method of the present invention. The data transmitting method further executes the step  1031 : according to the positive control signal and the negative control signal, respectively outputting the positive control voltage and the negative control voltage to the positive switch unit and the negative switch unit, so that the positive switch unit and the negative switch unit are controlled to stop transmitting the analog data to the output end. As shown in  FIG. 3 , the positive control unit  410 A and the negative control unit  510 A, according to the positive control signal S 1  and the negative control signal S 2 , respectively output the positive control voltage  400 A and the negative control voltage  500 A to the positive switch unit  420 A and the negative switch unit  520 A, so that the positive switch unit  420 A and the negative switch unit  520 A are controlled to stop transmitting the analog data  100  to the output end  60 . 
     The step  1033  includes, according to the positive control signal and the negative control signal, respectively stopping output of the positive control voltage and the negative control voltage to the positive switch unit and the negative switch unit, so that the positive switch unit and the negative switch unite are controlled to transmit the analog data to the output end. As shown in  FIG. 3 , the positive control unit  410 A and the negative control unit  510 A, according to the positive control signal S 1  and the negative control signal S 2 , respectively stop output of the positive control voltage  400 A and the negative control voltage  500 A to the positive switch unit  420 A and the negative switch unit  520 A, so that the positive switch unit  420 A and the negative switch unit  520 A are controlled to transmit the analog data  100  to the output end  60 . 
     Hence, the present invention utilizes the positive control signal S 1 , the negative control signal S 2 , the positive switch  40 , and the negative switch  50  to control transmission of the analog data  100  rather than disposing the high voltage switch, further decreasing the cost of material and the area of the chip. 
     Compared to prior arts, the driving circuit, the operational amplifier, and the data transmitting method of the present invention respectively control the positive control unit and the negative control unit of the operational amplifier according to the positive control signal and the negative control signal, so that the positive switch unit and the negative switch unit can control whether the analog data is transmitted to the output end or not, achieving the effect of the conventional high voltage switch. Hence, the embodiments of the present invention only utilize operational amplifiers of different design to control the analog data, eliminating the use of high voltage switches of the conventional display device 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.