This application claims the priority benefit of Taiwan application serial no. 93115037, filed on May 27, 2004.
1. Field of the Invention
This invention relates to a display and its driving circuit, and more particularly, the invention relates to a source driver, a source driver array, and driving circuit and display with the array.
2. Description of Related Art
Liquid crystal Display (LCD) has the characteristics being light, thin, small volume, low radiation, and saving power. These characteristics allow the space used in office area or home area to be saved, and also reduce the eye fatigue due to a long time of viewing on it. Therefore, in the planar display apparatus, LCD has the potential to replace the conventional CRT. However, as image resolution is more and more requested, it means that the data size for each frame of image is accordingly getting large. Therefore, the operation frequency of drivers for the planar display apparatus also increases.
Referring to
Referring to
The shift register 310 receives a start pulse signal DIO1 being externally input. The start pulse signal DIO1 is latched, so as to serve as the control signal for data sequential distribution. The display data signal DATA is then transmitted to the sampling register 320 via the data latch unit 330 and the data bus. This hold register 340 also receives the horizontal latch signal (LD). After the level shift unit 350 adjusts voltages of the display data signals, the signals are transmitted to the DAC unit 360. The Gamma voltage generator 380 receives a gamma voltage from external, and accordingly exports an output to the DAC unit 360 to serve as a reference for adjusting the analog signal. The adjusted display data signal is transmitted to the TFT LCD panel via the output buffer 370.
However, the bottleneck of this method is the path difference between the start pulse signal DIO1 at the receiving terminal and the operation clock signal CLK. It often causes latch error of the start pulse signal, and then limits the maximum operation frequency. The current method can only reach to about 100 MHz.
Referring to
It is an objective of the present invention to provide a source driver, a source driver array, and driving circuit with this array, and a display with the driving circuit, wherein the start pulse signal is improved. As a result, the conventional issue about the limitation of maximum operation frequency of the panel display driver due to the start pulse signal can be improved. Also and, the additional cost to raise the operation frequency in the conventional scheme, such as two-bus architectures, can be saved.
With respect to the objective, the invention provides a source driver, suitable for use to drive a display panel of a displaying apparatus. The source driver receives a display timing information provided from a timing controller. The source driver includes a start pulse generating circuit, used to receive a position code signal, and generates a start pulse signal based on the position code signal, so as to serve as a signal of data distribution control of a display data signal in the display timing information.
For the foregoing source driver, in one embodiment, when the position code signal being received by the source driver is used as the signal of data distribution control of the display data signal in the display timing information, a source-driver encoding signal (POS) is generated, to serve as the reference for the display data signal while starting to receive display timing information.
For the foregoing source driver, in one embodiment, for the source-driver encoding signal (POS) being the xth one with respect to the source driver in a source driver array, the source-driver encoding signal (POS) has the value of (x−1)*k. And, after counting value is equal to the source-driver encoding signal (POS), it starts to receive the display data signal in the display timing data. And, k is defined as the number of data needed to be latched by the source driver. The number of data to be latched by the source driver is the number of output channels of the source driver.
For the foregoing source driver in an embodiment, after the data of a horizontal line of the display data signal in the display timing data is completely latched, the timing controller issues a horizontal latch signal, so as to convert the data of the horizontal line from digital to analog and export the data to the display panel of the displaying device.
For the source driver in an embodiment, the start pulse generating circuit includes a start-code detection circuit, a synchronous counter, a decoding circuit and a digital comparator. The start code detection circuit is used to receive the display timing data transmitted from the timing controller, and to detect whether or not a horizontal latch signal appears in the display timing data. After the horizontal latch signal is detected, it is further detected whether or not a start code appears in the display data signal of the display timing data, so as to accordingly generate an enabling signal. The synchronous counter is coupled with the start code detection circuit, for receiving the enabling signal and the horizontal latch signal, and an operation clock signal, in which the horizontal latch signal causes a clear on the synchronous counter to be 0, and the counter starts to count according to the enabling signal. The decoding circuit is used to receive the position code signal, so as to accordingly generate a source-driver encoding signal (POS). The digital comparator is coupled to the synchronous counter and the decoding circuit, so as to compare value of the source-driver encoding signal (POS) with the value in the synchronous counter. It starts to receive the display data signal of the display timing data if the counting value is equal.
The invention provides a source driver array, suitable for use in a display panel of a displaying apparatus. The source driver array includes a plurality of source drivers, and each of the source drivers is coupled to a timing controller, so as to receive a display timing data. Each of the source drivers receives the corresponding one of a position code signal, in which the corresponding position code signal with respect to each source driver is determined according to a driving sequence of the source drivers in the source-driver array. According to the position code signal, a signal used as a data distribution control of the display data signal in the display timing data is transmitted to the display panel.
The invention provides a driving circuit, suitable for use in a display panel of a displaying apparatus, including a timing controller and a source driver array. The source driver array includes a plurality of source drivers. The timing controller is coupled with each of the source divers and provides a display timing data to each of the source drivers. Each of the source drivers receives a corresponding position code signal. The position code signal with respect to each source driver is determined according to a driving sequence of the source drivers in the source-driver array. According to the position code signal, a signal used as a data distribution control of the display data signal in the display timing data is transmitted to the display panel.
In the foregoing source driver array, each of the source drivers including a start pulse generating circuit is used to receive the position code signal and accordingly generate a start pulse signal, to be used as the signal of the data distribution control of the display data signal of the display timing data.
The invention provides a display apparatus, having a display panel and a driving circuit. The driving circuit includes a timing controller and a source driver array. The source driver array includes a plurality of source drivers. The timing controller is coupled with each of the source drivers and provides a display timing information to each of the source drivers. Each of the source drivers receives a corresponding position code signal. The corresponding position code signal with respect to each source driver is determined according to a driving sequence of the source drivers in the source-driver array. According to the position code signal, the signal used as the data distribution control of the display data signal in the display timing data is transmitted to the display panel.
The foregoing display apparatus is an active-drive display apparatus. In the embodiment, the display apparatus can be an amorphous silicon TFT LCD apparatus, a low temperature polysilicon TFT LCD apparatus, a liquid crystal on Silicon (LcoS) display apparatus, or an organic light-emitting diode (OLED) display apparatus.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
The invention is to provides an improved structure for a start pulse signal, so as to improve the conventional problems about the limitation of the maximum operation frequency of the panel display driver by the start pulse signal. And further, the cost due to the structure in the conventional scheme for raising the operation frequency can be saved.
For easy descriptions, the LCD is described by taking the AMTFT LCD as the example. However, the person skilled in the art knows that the present invention is a driving circuit for the display apparatus, and is suitable for use in various display apparatus, such as amorphous silicon TFT LCD display apparatus, a low temperature polysilicon TFT LCD apparatus, a liquid crystal on Silicon (LcoS) display apparatus, or an organic light-emitting diode (OLED) display apparatus.
In
The difference of the embodiment with the conventional scheme in
The number of bits for the position code signal P is determined according to the actual number of source drivers 5201-520n, which are needed to be defined. In the embodiment, since the needed number of the source drivers is n, the number of bits for the position code signal P must be greater than or equal to a number, which can represent the number n by binary. The position code signal P, received by each of the source drivers 5201-520n, is determined the arranging sequence order of the source drivers designed in the source driver array and is described by m bits. The received position code signal P is decimal 0 for the source driver 5201, as shown in Figure. The received position code signal P is decimal 1 for the source driver 5202. According to the arranging sequence of the source drivers, the similar situation is from left to right. As a result, the received position code signal P is decimal n−i for the source driver 520n. However, the foregoing design of the position code signal P is just an example of the invention.
In alternative design, it can be based on a specific arranging sequence of the source drivers 5201-520n to be driven in the source driver array 520 to adjust the position code signal P. It cannot be achieved for these features by the conventional manner about arranging the source drivers one after one, and the start pulse signal DIO being transmitted from a previous source driver to the next source driver. However, the specific arranging sequence described in the invention, for example for the n number of source drivers in the source driver array, can first drive the odd number of the source drivers and drive the even number of the source drivers later. This is a possible design according to the design of embodiment.
Referring to
This source driver 5201 includes a shift register 610, a sampling register 620 coupled to a data latch unit 630, a hold register 640, a level shift 650, a digital-to-analog converter (DAC) 660, an output buffer 670, and a start pulse generating circuit 690. The DAC 660 is coupled to a gamma voltage generator 680.
The shift register 610 receives the start pulse signal DIO generated by the start pulse generating circuit 690, so as to latch the start pulse signal DIO1 to serve as a control signal of data sequence distribution. The display data signal DATA is transmitted to the sampling register 620 via the data latch unit 630 and the data bus, and is further transmitted to the hold register 640. The hold register 640 also receives the horizontal latch signal (LD). After the voltage level of the display data signal is adjusted by the level shift unit 650, the signal is transmitted to the DAC unit 660. The gamma voltage generating apparatus 680 receives an external gamma voltage, which is accordingly transmitted to the DAC unit 660 and serves as a reference for adjusting the analog signal. Then, the adjusted display data signal is transmitted to the TFT LCD panel 530 via the output buffer 670.
Referring to
The operations for the start-code detection circuit 710 and the synchronous counter 720 are, for example, as follows. While in start, after the start-code detection circuit 710 receives the horizontal latch signal LD, it starts to detect whether or not a start code (S_code) appears in the display data signal DATA, and the LD signal also simultaneously clear the synchronous counter to be 0. After the start-code detection circuit 710 has detected that the start code (S_code) appears in the display data signal DATA, the start-code detection circuit 710 accordingly generates the enabling signal EN, used by the synchronous counter 720 for starting to count. In this embodiment, the synchronous counter 720 can be triggered by rising edge. However, it can be understood by the ordinary skilled artisans that the trigger can also be a falling edge. The counting result CNT of the synchronous counter 720 is transmitted to the digital comparator 730.
The decoding circuit 740 receives a position code signal P in multiple bits, such as m bits, and accordingly generates a source-driver encoding signal (POS), which is further transmitted to the digital comparator 730. Since the source driver array includes several source drivers, such as the source driver array 520 as shown in
Taking the example of the first source driver and the position code signal P being defined as 0 for description, when the received position code signal P is 0, the source-driver encoding signal (POS) with 0 is transmitted to the digital counter 730. After then, when the counting result CNT of the synchronous counter 720 is 0, the start pulse signal DIO is issued to the shift register. And for the second source driver as an example with the position code signal P being defined as 1, and the source-driver encoding signal (POS) being k, when the counting result CNT of the synchronous counter 720 is k, the start pulse signal DIO is issued to the shift register. With the same principle, for the xth source driver and position code signal P being defined as x−1, then the source-driver encoding signal (POS) is (x−1)*k, which is x−1 times k. When the counting result CNT of the synchronous counter 720 is (x−1)*k, a start pulse signal DIO is issued to the shift register. Here, k is defined as the number of data to be latched in a source driver, which is also the number of output channels in each of the source drivers. After data of a horizontal line are completely latched, the timing controller 510 at this moment issues the horizontal latch signal LD. After the data in, for example, a line buffer is converted from digital to analog, a gray level voltage is exported to the LCD panel.
Referring to
When the start-code detection circuit 710 has detected the start code (S_code) of the display data signal DATA at time t1 as shown in
The counting result CNT of the synchronous counter 720 is transmitted to the digital comparator 730. The first source driver with the position code signal being set by 0 is taken as the example for description. Since the position code signal P is 0, the source-driver encoding signal (POS) with 0 is transmitted to digital comparator 730. After then, when the counting result CNT of the synchronous counter 720 is 0, then the start pulse signal DIO(1) is issued to the shift register of the first source driver. For the second source driver as the example with the position code signal P being defined by 1, then, the source-driver encoding signal (POS) is k. When the counting result CNT of the synchronous counter 720 is k, at time T2 in
The driving circuit of panel displaying apparatus of the invention can solve the disadvantages that the maximum operation frequency in the conventional driving circuit of panel displaying apparatus is limited by the path difference between the start pulse input signal and the clock signal. The invention includes the following advantages. First, the driving circuit of the panel displaying apparatus of the invention has a relatively high operation frequency in comparing with the conventional driving circuit. In addition, the driving circuit of the invention need no the input of the start pulse signal DIO1. Instead, according to the data latching sequence, each of the source drivers is assigned with a specific position code signal P. Thereby, a start pulse signal with improved structure is provided, so that the conventional issues about the maximum operation frequency being limited by the start pulse signal in the panel displaying apparatus can be effectively solved. Also and, the fabrication cost of the additional structure in conventional manner to raise the operation frequency can be effectively saved.
The invention has been described using exemplary preferred embodiments. However, it is to be understood that the scope of the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements. The scope of the claims, therefore, should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Number | Date | Country | Kind |
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93115037 | May 2004 | TW | national |