Patent Application
20080001879
Reference will now be made to the drawings to describe preferred and exemplary embodiments of the present invention in detail.
The first substrate includes a number n (where n is a natural number) of gate lines 101 that are parallel to each other and that each extend along a first direction, and a number m (where m is also a natural number) of data lines 102 that are parallel to each other and that each extend along a second direction orthogonal to the first direction.
The gate lines 101 are driven by the gate driving circuit 110. The data lines 102 are driven by the data driving circuit 120. The gate lines 101 and the data lines 102 cross each other, thereby defining a plurality of pixel regions 105. The first substrate also includes a plurality of pixel electrodes (not shown) disposed in the pixel regions 105, respectively.
The first substrate further includes a plurality of TFTs 150 disposed in the pixel regions 105, respectively. The TFTs 150 function as switching elements. Each TFT 150 is provided in the vicinity of a point of intersection of a corresponding gate line 101 and a corresponding data line 102. Each TFT 150 includes a gate electrode (not labeled), a source electrode (not labeled), and a drain electrode (not labeled).
The gate electrode of the TFT 150 is connected to the corresponding gate line 101. The source electrode of the TFT 150 is connected to the corresponding data line 102. The drain electrode of the TFT 150 is connected to the corresponding pixel electrode.
The data signals “Vd′” consist of a plurality of constant high voltages VH and a plurality of constant low voltages VL successively transmitted. When the data signal is on high voltage, light rays transmit through the pixel region 105, and the light transmitting ratio “T %” of the pixel region 105 is constant. When the data signal is on low voltage, no light rays transmit through the pixel region 105, and the pixel region 105 displays a black image. The proportion of the duration of the VH to the summation of the durations of the VH and the VL is defined as a duty cycle. A method of driving the LCD device 10 includes the following steps:
A frame period is divided into three sub-frame periods. In the first sub-frame period t1′, the LED matrix 160 generates red rays. The gate driving circuit 110 generates a plurality of scanning signals, and applies the scanning signals to the gate lines 101. The scanning signals are high voltages. The high voltages turn on the corresponding TFTs 150. Thus, the data driving circuit 120 applies data signals to the pixel electrodes via the data lines 102 and the TFTs 150.
When the data signal applied to each pixel electrode is on high voltage, the red rays transmit through the pixel region 105, and the red light transmitting ratio “T %” of the pixel region 105 is constant. When the data signal is on low voltage, no red rays transmit through the pixel region 105, and the pixel region 105 displays a black image. The proportion of the duration of the VH to the summation of the durations of the VH and the VL is defined as a duty cycle. Thus the duration of the red rays transmitting through each pixel region 105 is controlled by the duty cycle of the corresponding data signal applied to the pixel electrode.
In the second sub-frame period t2′, the LED matrix 160 generates green rays. The gate driving circuit 110 generates a plurality of scanning signals, and applies the scanning signals to the gate lines 101. The scanning signals are high voltages. The high voltages turn on the TFTs 150. Thus, the data driving circuit 120 applies data signals to the pixel electrodes via the data lines 102 and the TFTs 150.
When the data signal applied to each pixel electrode is on high voltage, the green rays transmit through the pixel region 105, and the green light transmitting ratio “T %” of the pixel region 105 is constant. The constant transmitting ratio “T %” has the same value as that in the foregoing first sub-frame-period t1′. When the data signal is on low voltage, no green rays transmit through the pixel region 105, and the pixel region 105 displays a black image. The proportion of the duration of the VH to the summation of the durations of the VH and the VL is defined as a duty cycle. Thus the duration of the green rays transmitting through each pixel region 105 is controlled by the duty cycle of the corresponding data signal applied to the pixel electrode.
In the third sub-frame period t3′, the LED matrix 160 generates blue rays. The gate driving circuit 110 generates a plurality of scanning signals, and applies the scanning signals to the gate lines 101. The scanning signals are high voltages. The high voltages turn on the corresponding TFTs 150. Thus, the data driving circuit 120 applies data signals to the pixel electrodes via the data lines 102 and the TFTs 150.
When the data signal applied to the pixel electrode is on high voltage, the blue rays transmit through the pixel region 105, and the blue light transmitting ratio “T %” of the pixel region 105 is constant. The constant transmitting ratio “T %” has the same value as that in the foregoing first sub-frame period t1′. When the data signal is on low voltage, no blue rays transmit through the pixel region 105, and the pixel region 105 displays a black image. The proportion of the duration of the VH to the summation of the durations of the VH and the VL is defined as a duty cycle. Thus the duration of the blue rays transmitting through each pixel region 105 is controlled by the duty cycle of the corresponding data signal applied to the pixel electrode.
The red rays in the first sub-frame period t1′, the green rays in the second sub-frame period t2′, and the blue rays in the third sub-frame period t3′ are mixed to form a color image in a frame period. The color images in all the frames form a dynamic picture that is viewed on a display screen of the LCD device 10.
A frame period is typically 16.7 milliseconds. The proportion of the first sub-frame period t1′ to a frame period, the proportion of the second sub-frame period t2′ to the same frame period, and the proportion of the third sub-frame period t3′ to the same frame period are adjustable, so that a white balance can be controlled.
As detailed above, in a conventional method of driving an LCD device, the value of the data signal applied to each pixel electrode in each sub-frame is controlled. Thereby, the LCD device controls the chroma of each pixel region in a frame. Further, the essential resistance of the data lines is liable to cause errors of the data signals Vd applied to each pixel electrode. This leads to inaccuracies of the chroma of each pixel region in a frame. Compare this with the above-described method of driving the LCD device 10, which is by means of controlling the duty cycle of the data signal applied to each pixel electrode in each sub-frame. Thereby, the LCD device 10 controls each primary color rays' duration of transmission in each pixel region 105 in a frame. Thus it is by means of controlling the duty cycle of the data signal applied to each pixel electrode in each sub-frame that the LCD device 10 controls the chroma of each pixel region 105 in a frame. Thus, the accuracy of the chroma of the image in each frame is high.
Further or alternative embodiments may include the following. In one example, the LED matrix generates the red rays, the green rays, and the blue rays in another sequence in a frame period. In another example, the LCD device 10 may include another kind of light source instead of an LED matrix. For example, the light source can be a plurality of cold cathode fluorescent lamps (CCFLs), which emit at least three primary color rays in at least three different sub-frame periods respectively.
It is to be further understood that even though numerous characteristics and advantages of preferred and exemplary embodiments have been set out in the foregoing description, together with details of structures and functions associated with the embodiments, the disclosure is illustrative only, and changes may be made in detail (including in matters of shape, size, and arrangement of parts) within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 95123847 | Jun 2006 | TW | national |
