This application claims the benefit of Taiwan application Serial No. 095128890, filed Aug. 7, 2006, the subject matter of which is incorporated herein by reference.
1. Field of the Invention
The invention relates in general to a data transmitting method of a liquid crystal display (LCD), and more particularly to a data transmitting method of a LCD capable of reducing the number of buses between a source driver and a timing controller.
2. Description of the Related Art
However, when the sub-pixel data of each sub-pixel includes the eight sets of bit data, 24 buses between the source driver 104 and the timing controller 102 are needed to transmit data between the source driver 104 and the timing controller 102. The buses occupy a larger layout area on a printed circuit board (PCB) so that the cost of the LCD is higher. Meanwhile, the buses make the timing controller have the higher loading.
The invention is directed to a liquid crystal display (LCD) and a data transmitting method thereof, in which a fewer buses are utilized for data transmission, and a source driver of the invention may be applied to the conventional LCD architecture according to a special data mapping method. Thus, the LCD having the source driver and the data transmitting method according to the invention have the advantages of the low cost and the lower output loading of a timing controller, and the source driver of the invention may also be advantageously applied to the conventional LCD architecture.
According to a first aspect of the present invention, a source driver of a liquid crystal display (LCD) is provided. The LCD includes a pixel array having pixels each including a sub-pixel. Sub-pixel data of the sub-pixel includes first and second bit data. The source driver includes a receiver, a line buffer and a first transmission path. The receiver includes first and second receiving units for respectively receiving the first and second bit data and outputting the first and second bit data. The line buffer includes first and second registers for respectively receiving the first and second bit data outputted from the receiver. The first transmission path electrically connects an output terminal of the first register and an input terminal of the second register. The source driver includes a first mapping operation mode. When the source driver operates in the first mapping operation mode, the second receiving unit is disabled, the first receiving unit is enabled to receive the first bit data and the second bit data, and the first transmission path is enabled to input the second bit data received by the first receiving unit to the second register.
According to a second aspect of the present invention, a data transmitting method is provided. The data transmitting method is applied to a data transmission interface to input a data signal to an electronic device. The data signal includes a first set of data and a second set of data. The electronic device includes a first receiving unit, a second receiving unit, a third receiving unit, a fourth receiving unit and corresponding first to fourth registers. This transmitting method includes the following steps. First, the first and second receiving units are disabled. Next, the first set of data is inputted to the electronic device through the third and fourth receiving units and inputted to the third register and the fourth register during a first clock cycle of a clock signal. Thereafter, the second set of data is inputted to the electronic device through the third and fourth receiving units and inputted to the third register and the fourth register while the first set of data stored in the third register and the fourth register is inputted to the first register and the second register during a second clock cycle of the clock signal.
The invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings.
The data transmitting method of the liquid crystal display (LCD) according to the invention disables half of receiving units in a receiver of a source driver. Thus, the source driver receives sub-pixel data outputted from a timing controller through the halved numbers of buses and receiving units, and the object of reducing the number of buses between the timing controller and the source driver may be achieved. In the embodiments of the present invention, the data transmitting method of the LCD further enables the source driver to be applied to the conventional LCD architecture according to a special bit data mapping method.
The timing controller 202 is coupled to the receiving units 206, 208, 210 and 212 through the buses 2051 and 2052, 2053 and 2054, 2055 and 2056 and 2057 and 2058, respectively, to input the red sub-pixel data to the source driver 204. The red sub-pixel data includes, for example, bit data Bit0 to Bit7. The receiving units 206 to 212 correspond to the registers 214 to 220 and are coupled to input terminals of the registers 214 to 220, respectively. The transmission paths 204b1, 204b2, 204b3 and 204b4 are coupled to output terminals of the registers 214, 216, 218 and 220 and the input terminals of the registers 218, 220, 214 and 216, respectively.
The source driver 204 in the embodiment of the invention has a first mapping operation mode and a second mapping operation mode. Next, the first and second mapping operation modes will be described according to the following embodiments.
At a rising edge of a first clock cycle of the clock signal CLK, the timing controller 202 differentially inputs the bit data Bit4 and Bit6 to the receiving units 206 and 208 through the buses 2051 and 2052 and the buses 2053 and 2054, respectively. The receiving units 206 and 208 respectively store the bit data Bit4 and Bit6 to the registers 214 and 216. At a falling edge of the first clock cycle of the clock signal CLK, the timing controller 202 differentially inputs the bit data Bit5 and Bit7 to the receiving units 206 and 208 through the buses 2051 and 2052 and the buses 2053 and 2054, respectively. The receiving units 206 and 208 also respectively store the bit data Bit5 and Bit7 to the registers 214 and 216. Thus, the registers 214 and 216 respectively store the bit data Bit4 and Bit5 and the bit data Bit6 and Bit7 after the first clock cycle of the clock signal CLK.
At a rising edge of a second clock cycle of the clock signal CLK, the registers 214 and 216 output the bit data Bit4 and Bit6 to the registers 218 and 220 through the transmission paths 204b1 and 204b2, respectively. Meanwhile, the timing controller 202 differentially inputs the bit data Bit0 and Bit2 to the receiving units 206 and 208 through the buses 2051 and 2052 and the buses 2053 and 2054, respectively. The receiving units 206 and 208 respectively store the bit data Bit0 and Bit2 to the registers 214 and 216.
At a falling edge of the second clock cycle of the clock signal CLK, the registers 214 and 216 output the bit data Bit5 and Bit7 to the registers 218 and 220 through the transmission paths 204b1 and 204b2, respectively. Meanwhile, the timing controller 202 differentially inputs the bit data Bit1 and Bit3 to the receiving units 206 and 208 through the buses 2051 and 2052 and the buses 2053 and 2054, respectively. The receiving units 206 and 208 respectively store the bit data Bit1 and Bit3 to the registers 214 and 216. Consequently, the registers 214, 216, 218 and 220 respectively store the bit data Bit0 and Bit1, Bit2 and Bit3, Bit4 and Bit5 and Bit6 and Bit7 after the second clock cycle of the clock signal CLK.
Next, the registers 214 to 220 respectively output a plurality of output signals SO1′ to SO4′ during the next first clock cycle of the clock signal CLK. The output signals SO1′ to SO4′ respectively include the bit data Bit0, Bit2, Bit4 and Bit6 at the rising edge of the next first clock cycle of the clock signal CLK, and respectively include the bit data Bit1, Bit3, bit5 and Bit7 at the falling edge of the next first clock cycle of the clock signal CLK. Thus, the first mapping operation mode effectively achieves the data transmission between the timing controller 202 and the source driver 204 with the halved number of buses 2051 to 2054.
The register 214 of the red first module 402 is adjacent to the register 218 of the red third module 406, and a capacitor C1 is disposed between the registers 214 and 218. The register 216 of the red second module 404 is adjacent to the register 220 of the red fourth module 408, and a capacitor C3 is disposed between the registers 216 and 220. The receiving unit 210 of the red third module 406 is adjacent to the receiving unit 208 of the red second module 404, and a capacitor C2 is disposed between the receiving units 210 and 208. Thus, when the source driver 204 operates in the first mapping operation mode, only the capacitors C1 and C2 are left on critical paths of the data transmission between the registers 214 and 218 and the registers 216 and 220. Consequently, lengths of the critical paths of the data transmission between the registers 214 and 218 and the registers 216 and 220 in the conventional source driver layout method may be shortened.
First, as shown in step 502, the receiving units 210 and 212 are disabled.
Next, as shown in step 504, the bit data Bit4 and Bit5 are inputted to the register 214 through the buses 2051 and 2052 and the receiving unit 206 and the bit data Bit6 and Bit7 are inputted to the register 216 through the buses 2053 and 2054 and the receiving unit 208 during the first clock cycle of the clock signal CLK.
Thereafter, as shown in step 506, the bit data Bit0 and Bit1 are inputted to the register 214 through the buses 2051 and 2052 and the receiving unit 206, and the bit data Bit2 and Bit3 are inputted to the register 216 through the buses 2053 and 2054 and the receiving unit 208 during the second clock cycle of the clock signal CLK. Also, during the second clock cycle of the clock signal CLK, the bit data Bit4 and Bit5 are inputted to the register 218 through the transmission path 204b1, and the bit data Bit6 and Bit7 are inputted to the register 220 through the transmission path 204b2.
In this illustrated embodiment, the red sub-pixel data includes eight sets of bit data Bit0 to Bit7. However, the red sub-pixel data of this embodiment may also include more or less than eight sets of bit data, such as six sets of bit data. When the red sub-pixel data only includes six sets of bit data, for example, the timing controller 202 does not output the bit data Bit0 and Bit1 to perform the data transmission when the red sub-pixel data only includes six sets of bit data during the second clock cycle of the clock signal CLK.
In this illustrated embodiment, each pixel of the pixel array includes one red sub-pixel. However, each pixel of the pixel array of this embodiment may include multiple sub-pixels, such as the red, green and blue sub-pixels. Each color of sub-pixel may operate in a similar manner according to the operation of the red sub-pixel. In this illustrated embodiment, only the circuits, such as the circuit layout of the receiving units 206 to 212 and the registers 214 to 220, relating to the transmission of the red sub-pixel data are described. However, the circuit layouts for the transmission of other colors of sub-pixel data may also be derived in a similar manner according to the circuit layout of the circuit relating to the red sub-pixel data.
The receiving units 206 to 212 according to this embodiment are, for example, double edge sampling receiving units for sampling the bit data on the buses 2051 to 2058 at the rising edge and the falling edge of the clock signal CLK. The buses 2051 to 2058 according to this embodiment are, for example, reduced swing differential signal (RSDS) buses, which may be paired to form differential channels for differentially transmitting the signals.
The source driver 204 of this embodiment differs from the conventional source driver in that the source driver 204 of this embodiment needs two clock cycles of the clock signal CLK to receive eight sets of bit data of one sub-pixel data. Thus, in order to make the LCD have the source driver of this embodiment and the conventional LCD have the similar displaying effect, the frequency of the clock signal CLK of this embodiment is twice that of the clock signal of the conventional LCD. For example, when the frame frequency of the LCD 200 is 60 Hz, the frequency of the clock signal CLK is 90 MHz.
According to the first embodiment, the source driver 204 may perform the data transmission between the timing controller 202 and the source driver 204 with the halved number of buses. Meanwhile, the source driver 204 of this embodiment only needs two clock cycles of the clock signal CLK to completely receive the eight sets of bit data because the number of the used buses is halved.
At this time, the data transmitting method in the LCD 200 of
First, in the step 502 of
Next, in the step 504 of
Then, in the step 506 of
The source driver 204 of this embodiment further includes a conventional mapping operation mode. When the source driver 204 operates in the conventional mapping operation mode, the transmission paths 204b1 to 204b4 are disabled and the receiving units 206 to 212 are enabled. At this time, the source driver 204 performs the data transmission between the timing controller 202 and the source driver 204 through the receiving units 206 to 212 and the buses 2051 to 2058. In addition, the source driver 204 of the above-mentioned embodiment further includes a selection pin (not shown) for switching the operation mode of the source driver 204 to the first mapping operation mode, the second mapping operation mode or the conventional mapping operation mode. The embodiments are illustrated by taking the source driver and the method for transmitting the sub-pixel data including eight sets of bit data as an example. However, the sub-pixel data is not restricted to the eight sets of bit data. For example, the sub-pixel data may include six sets of bit data.
The source driver according to the invention can receive the sub-pixel data outputted from the timing controller through the halved number of receiving units in the disabled receiver and the halved number of buses during two clock cycles of the clock signal. Thus, the LCD with the source driver according to the embodiments of the invention can reduce the layout area of the buses on the printed circuit board (PCB) so that the LCD with the source driver according to the embodiments of the invention advantageously has the lower cost and the lower output loading of the timing controller. The source driver according to the embodiments of the invention further has the conventional mapping operation mode. Meanwhile, when the source driver in the embodiments of the invention is operating in the first or second mapping operation mode, the bit data can be received according to the specific bit data mapping method so that the source driver of the invention further has the advantage of being applied to the conventional LCD architecture.
While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.
Number | Date | Country | Kind |
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95128890 A | Aug 2006 | TW | national |
Number | Name | Date | Kind |
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5786800 | Gyouten | Jul 1998 | A |
5821948 | Kawamoto et al. | Oct 1998 | A |
20050285839 | Kim | Dec 2005 | A1 |
20060256099 | Tashiro | Nov 2006 | A1 |
Number | Date | Country | |
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20080030453 A1 | Feb 2008 | US |