Patent Application
20070057904
1. Field of the Invention
The present invention relates to a scan method for driving a display and a display therewith, and more particularly, to a multiple scan method for driving a display and a display therewith, by dividing active pixel area and alternately driving these divided active pixel area for expediting response time of these active pixels in the display.
2. Description of Related Art
As computer technology advances and as Internet and multimedia are highly being developed, current information is transmitted in digital form instead of analog form, and novel display apparatuses are being invented. A conventional CRT, structured with an inner electronic cavity structure occupying substantial space, and radiation harmful to human eyes, is gradually being eliminated from the display market. Therefore, a flat panel display fabricated with optoelectronic technology and semiconductor process, such as a liquid crystal display (LCD), an organic light emitting display (OLED), or a plasma display panel (PDP) display, is becoming main trend of research and development.
A plurality of pixels arranged in an array constitutes a frame in a display. The pixel is a basic unit for displaying in the display. In a flat panel display, for example, a driving potential is generated according to a pixel data to charge the pixel for showing luminance accordingly. A display is generally driven by a horizontal sync signal and a vertical sync signal, which is applied to a gate driving unit and a source driving unit respectively. The horizontal sync signal determines a number of rows to display in a specific time period, and the vertical sync signal determines a display time length of each frame. A time interval taken between every two adjacent vertical sync signals is a frame period. The vertical sync signal can as well be characterized with a reciprocal of the frame period, i.e. a frame rate. In general, a frame rate of a computer monitor is not less than 60 Hz, i.e., a display device is able to show more than 60 frame data in a second, where each frame period is no longer than 16.7 ms.
According to the flat panel display technology, an ordinary vertical scanning frequency is 60 Hz. A conventional scanning method is implemented by a source driving unit and a gate driving unit which are operated once of each in a frame period, which is shown in
Architecture for speeding up the response time of the pixels is proposed in the US Patent Application Publication No. US2002/017640, titled “Method of Display by Sub-Frame Driving”, pub. Date on Nov. 21, 2002. In the architecture, under the same vertical display condition, e.g. a 60 Hz frame rate is provided, that is, a frame lasts for about 16.7 ms. A frame period, where a picture having mxn pixels thereof, is divided into k sub frame periods. A driving potential is applied to the pixels, such that the liquid crystal response time is expedited. The driving potential is a target potential plus a driving offset for respective sub frame period. Referring to
In
According to the conventional art described above, however, the driving offset potential provided is not precise as desired, the driving potential for each sub frame cannot be expected, which results in unstable picture quality in a LCD. Furthermore, the driving offset amount generated according to conventional art is based on an over-driving technique. Therefore, a frame buffer, e.g. an SDRAM in general, for storing pixel data, and a memory, e.g. an electrically erasable programmable read-only memory (EEPROM) in general, for storing a look up table are additionally disposed, for calculating driving offset potential correspondingly.
According to the above descriptions, hardware such as a frame buffer and a memory for storing a look up table are additionally disposed for obtaining driving offset potentials, where a precise driving offset potential is hardly achieved by over-driving technique without complicated calculation mechanism. Therefore, a novel multiple driving method for a LCD is desired, where additional hardware is not needed, and driving potential can be easily and precisely generated.
Accordingly, the present invention is directed to a multiple scan method for driving a display and a display therewith. The multiple scan method is achieved by alternately driving the active pixels in the display for expediting response time of these active pixels to reach the target luminance in the display. The pixels in the display are charged or discharged twice or more times within one frame period.
In one embodiment of the proposed multiple scan method for driving a display, the pixels arranged as a matrix constituted with a plurality of rows and columns are divided into a plurality of pixel blocks, which are driven by a gate driving device including a plurality of gate drivers. The pixels within each of the pixel blocks are charged or discharged twice or more times with a target voltage within one frame period in order to speed up the response time of the pixels to reach a target luminance. The times for the pixels within each of the pixel blocks being charged or discharged and the time intervals for the driving are determined according to the design.
According to an embodiment of the present invention, a multiple scanning method for driving a display is provided. The display comprises a display panel, a source driving device and a gate driving device, where the gate driving device comprises a plurality of gate drivers. The method comprising dividing display panel into a plurality of pixel blocks for driving, each of the pixel blocks comprising a plurality of pixels and is driven by one of the gate drivers and alternately scanning the pixel blocks to selectively charge the pixels in the pixel blocks with a target voltage twice or more times within a frame period, thereby to speed up the response time of the pixels to reach a target luminance.
In the multiple scanning method for driving a display as above, if the gate driving device has X gate drivers and each of the gate drivers has N output channels, a scan cycle coefficient M is defined as every M scan lines, the gate driver scan the M scan lines again, a time to charge the pixels for the second time is (M×T)/(2×N×X), where T is the frame period.
In the multiple scanning method for driving a display as above, if the gate driving device has X gate drivers and each of the gate drivers has N output channels, a scan cycle coefficient M is defined as every M scan lines, the gate driver scan the M scan lines again, a sequence number S is defined as N/M, a second time point to charge the pixels for the second time is (2−1)×(M×T)/(R×N×X), and a third time point for driving the pixel is (3−1) ×(M×T)/(R×N×X), wherein S, N, X, M and R are integers.
The invention proposes a multiple scan method for driving a display by alternately driving the active pixels in the display for expediting response time of these active pixels to reach the target luminance in the display. The pixels in the display are charged or discharged twice or more times within one frame period.
In one embodiment of the proposed multiple scan method for driving a display, the pixels arranged as a matrix constituted with a plurality of rows and columns are divided into a plurality of pixel blocks, which are driven by a gate driving device including a plurality of gate drivers. The pixels within each of the pixel blocks are charged or discharged twice or more times with a target voltage within one frame period in order to speed up the response time of the pixels to reach a target luminance. The times for the pixels within each of the pixel blocks being charged or discharged and the time intervals for the driving are determined according to the design. In the invention, the target voltage is used twice or more times to charge the pixels to speed up the response time of the pixels to reach a target luminance.
A multiple scan method for driving a display by dividing active pixels into a plurality of blocks and alternately driving these divided pixel blocks for expediting response time of these active pixels in the display. In one embodiment of the invention, the pixels in the display are charged or discharged twice or more times with a target voltage within one frame period in order to speed up the response time of the pixels to reach a target luminance. By such design, the response time is shortened and quality for showing motion pictures is significantly improved. The scan method for driving is applicable to any type of displays, including a liquid crystal display (LCD), organic light emitter diode display (OLED), plasma display panel (PDP), etc.
In one embodiment of a multiple scan method for driving a display of the present invention, the pixels arranged as a matrix constituted with a plurality of rows and columns are divided into a plurality of pixel blocks, which are driven by a gate driving device including a plurality of gate drivers. The pixels within each of the pixel blocks are charged or discharged twice or more times with a target voltage within one frame period in order to speed up the response time of the pixels to reach a target luminance. The times for the pixels within each of the pixel blocks being charged or discharged and the time intervals for the driving are determined according to the design.
Referring to
To illustrate the embodiment of the present invention, a frame having m×n pixel data is taken as an example, where m=1024×3, n=768. As shown in
In the embodiment, each of the gate drivers 332, 334 and 336 has 256 output channels. Referring to
Then the gate driver 332 goes back to turn on the transistor coupled to the first scan line, and successively turn on the transistor coupled to the second scan line, and then successively turn on the other transistors coupled to the scan lines corresponding to the other channels of the gate driver 332 until the 256 scan lines are driven again by the gate driver 332. The first sub frame including 1024×3×256 pixel data is displayed again in the pixel block 312. In the embodiment, if the output channels of the gate driver 332 are CH1˜CH256, the order for driving the scan lines corresponding to these output channels are CH1, CH2, CH3 . . . , CH255, CH256, CH1, CH2, CH3 . . . , CH255 and CH256. The pixels in the in the pixel block 312 are charged or discharged twice within one frame period in order to speed up the response time of the pixels to reach a target luminance.
After the first sub frame is displayed in the pixel block 312 twice, the gate driver 334 begins to successively turn on the transistors coupled to the scan lines corresponding to the channels of the gate driver 334 until the 256 scan lines are driven by the gate driver 334 and pixels connected to the transistors are successively and selectively charged with a target voltage applied from the data lines coupled to the pixels. A second sub frame including 1024×3×256 pixel data is displayed in the pixel block 314. Then the gate driver 334 goes back again to successively turn on the transistors coupled to the scan lines corresponding to the channels of the gate driver 334 until the 256 scan lines are driven by the gate driver 334. The second sub frame including 1024×3×256 pixel data is displayed again in the pixel block 314. In the embodiment, if the output channels of the gate driver 334 are CH1˜CH256, the order for driving the scan lines corresponding to these output channels are CH1, CH2, CH3 . . . , CH255, CH256, CH1, CH2, CH3 . . . , CH255 and CH256.
After the second sub frame is displayed in the pixel block 314 twice, the gate driver 336 begins to successively turn on the transistors coupled to the scan lines corresponding to the channels of the gate driver 336 until the 256 scan lines are driven by the gate driver 336 and pixels connected to the transistors are successively and selectively charged with a target voltage applied from the data lines coupled to the pixels. A third sub frame including 1024×3×256 pixel data is displayed in the pixel block 316 twice, as the similar manner disclosed above.
According to the embodiment of the invention, as shown in
Referring to
According to one embodiment of the present invention, if the gate driving device has only two gate drivers in a display, a frame can be divided into two pixel blocks for driving within a frame period. The pixel is charged with a target voltage in the beginning and substantially after T/4 from the beginning, the pixel is charged again with the target voltage. That is, a frame is divided into two pixel blocks for scanning purpose, Ton_1 is the time the driving is initiated and Ton_2 becomes T/4. Generally speaking, if the gate driving device has X gate drivers in a display, the time Ton_2 to charge the pixel for the second time can be expressed by equation T/(2×X), where T is the frame period.
Furthermore, according to another embodiment of the present invention, if the gate driving device has X gate drivers and each of the gate drivers has N output channels. A scan cycle coefficient M is defined as every M scan lines, the gate driver will rescan again. In the case that M=256, it means that every 256 scan lines, the gate driver will rescan from the first scan line of all of the scan lines coupled to the gate driver. The time Ton_2 to charge the pixel for the second time can be expressed by equation (M×T)/(2×N×X), where T is the frame period.
As described above, the invention provides a multiple scan method for driving a display by dividing active pixels into a plurality of pixel blocks and alternately driving these divided pixel blocks for expediting response time of these active pixels to reach the target luminance in the display. The pixels in the display are charged or discharged twice or more times within one frame period. It is assumed that a refresh coefficient R is defined as the times the pixels are charged or discharged. In the case that R=2, which is shown in the first embodiment, the pixels in the display are charged or discharged twice within one frame period and the active pixels are divided into three pixel blocks for the driving purpose. The scanning step of the display follows the order
TG111→TG112→TG211→TG212→TG311→TG312, as shown in
TG111→TG112→TG113→TG211→TG212→TG213→TG311→TG312→TG313.
In the multiple scanning method of the invention, a plurality of coefficients can be determined in advance for different designs as desired. It is assumed that the gate driving device has X gate drivers and each of the gate drivers has N output channels. A scan cycle coefficient is defined as M and a refresh coefficient is defined as R, as introduced above. A sequence number S is defined as N/M, which means that in the N channels of each of the gate driver, the gate driver will rescan every M scan lines and S times for performing the M-scan-line scanning operation. A scanning sequence according to the present invention is:
TG111→TG112→TG113→TG11R→TG121→TG122→. . . →TG1SR→TG211→TG212→TG213→T G21R→TG221→TG222→. . . →TG2SR→. . . →TGXSR. For example, a first time point Ton_1 for driving the pixel is (1−1)×(M×T)/(R×N×X)=0, a second time point Ton_2 for driving the pixel is (2−1)×(M×xT)/(R×N×X), a third time point Ton_3 for driving the pixel is (3−1) ×(M×T)/(R×N×X), etc., wherein S, N, X, M and R are integers.
The invention proposes a multiple scan method for driving a display by alternately driving the active pixels in the display for expediting response time of these active pixels to reach the target luminance in the display. The pixels in the display are charged or discharged twice or more times within one frame period.
In one embodiment of the proposed multiple scan method for driving a display, the pixels arranged as a matrix constituted with a plurality of rows and columns are divided into a plurality of pixel blocks, which are driven by a gate driving device including a plurality of gate drivers. The pixels within each of the pixel blocks are charged or discharged twice or more times with a target voltage within one frame period in order to speed up the response time of the pixels to reach a target luminance. The times for the pixels within each of the pixel blocks being charged or discharged and the time intervals for the driving are determined according to the design. In the invention, the target voltage is used twice or more times to charge the pixels and there is no such problem in the conventional art that when the driving offset potential provided is not precise as desired, the driving potential for each sub frame cannot be expected, which results in unstable picture quality in the display. Furthermore, in the invention, it is not required to add the a frame buffer for storing pixel data and a memory for storing a look up table to calculate driving offset potential correspondingly.
Although the invention has been described with reference to a particular embodiment thereof, it will be apparent to those skilled in the art that modifications to the described embodiment may be made without departing from the spirit of the invention. Accordingly, the scope of the invention will be defined by the attached claims and not by the above detailed description.
