This application claims the benefit of Taiwan application Serial No. 101120319, filed Jun. 6, 2012, the subject matter of which is incorporated herein by reference.
1. Field of the Invention
The invention relates in general to a display and a driving method thereof, and more particularly to a display applying low color shift (LCS) technology and a driving method thereof.
2. Description of the Related Art
Liquid crystal display (LCD), having the advantages of small volume, light weight and low radiation, has been widely used in various fields of application. In general, a liquid crystal display includes an LCD panel and a backlight module. The LCD panel determines the transmission of each pixel in response to a display data voltage applied thereon. The backlight module uniformly projects a back light to the LCD panel. Thus, the liquid crystal display may correspondingly display the display data.
Since the voltage-transmission curve of each pixel varies with the user's viewing angle (relative to the display surface of the liquid crystal display), color shift arises accordingly. In terms of the existing charge sharing low color shift (LCS), corresponding display areas of different scan lines of the liquid crystal display have different brightness levels, hence resulting in band mura. Therefore, how to provide an LCS liquid crystal display capable of effectively reducing the band mura effect and a driving method has become a prominent task for the industries.
According to one embodiment of the present invention, a display including a first substrate, a second substrate, a scan driver, a data driver and a control driver is provided. The first substrate has a common electrode. The second substrate includes M scan lines, N data lines, M control lines, several metal lines and M×N pixels, wherein M and N are natural numbers greater than 1, and several metal line are disposed on the second substrate and correspond to the common electrode. The (i,j)th of the MxN pixels includes a first sub-pixel and a second sub-pixel. The first sub-pixel is electrically connected to the ith scan line and the jth data line, wherein i and j respectively are a natural number smaller than or equal to M and a natural number smaller than or equal to N, and the second sub-pixel is electrically connected to the ith scan line, the jth data line and the ith control lines and further has a discharge switch. The scan driver is electrically connected to each of the M scan lines for providing M scan signals to drive M scan lines in M scan periods respectively. The data driver is electrically connected to N data lines for providing a data voltage to each of the N data lines in each of the M scan periods. The control driver is electrically connected to each of the M control lines for providing (M−K) control signals to drive the first to the (M−K)th control lines in the (K+1)th to the Mth scan periods respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)th control lines. The control driver further drives one of the metal lines to trigger a level shifting event in each of the first to the Kth scan periods, so that a level shifting event is correspondingly triggered on a scan line and a metal line in each of the first to the Kth scan periods.
According to another embodiment of the present invention, a display including a first substrate, a second substrate, a scan driver, a data driver and a control driver is provided. The first substrate has a common electrode. The second substrate includes M scan lines, N data lines, M control lines and MxN pixels, wherein M and N are natural numbers greater than 1. The (i,j)th of the MxN pixels includes a first sub-pixel and a second sub-pixel. The first sub-pixel is electrically connected to the ith scan line and the jth data line, wherein i and j respectively are a natural number smaller than or equal to M and a natural number smaller than or equal to N. The second sub-pixel is electrically connected to the ith scan line, the jth data line and the ith control lines, and further has a discharge switch. The scan driver is electrically connected to each of the M scan lines for providing M scan signals to drive M scan lines in M scan periods respectively. The data driver is electrically connected to N data lines for providing a data voltage to each of the N data lines in each of the M scan periods. The control driver is electrically connected to each of the M control lines for providing (M−K) control signals to drive the first to the (M−K)th of the M control lines in the (K+1)th to the Mth scan periods respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)th control lines. The control driver further drives the second to the Kth M control lines to trigger level shifting events in the first to the (K−1)th scan periods respectively, so that level shifting events are triggered on a scan line and a control line in the first to the (K−1)th scan periods.
According to an alternate embodiment of the present invention, a driving method applied in a display is provided. The display includes a first substrate, a second substrate, a scan driver, a data driver and a control driver. The first substrate has a common electrode. The second substrate includes M scan lines, N data lines, M control lines, several metal lines and M×N pixels, wherein M and N are natural numbers greater than 1. The metal lines are disposed on the second substrate, and correspond to the common electrode. Each of the MxN pixels includes a first sub-pixel and a second sub-pixel. The second sub-pixel further has a discharge switch. The driving method includes the following steps of: applying the scan driver to provide M scan signals to drive M scan lines in the M scan periods respectively; applying the data driver to provide a data voltage to each of the N data lines in each of the M scan periods; applying the control driver to provide (M−K) control signals to drive the first to the (M−K)th of the M control lines in the (K+1)th to the Mth scan periods respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)th control lines; and applying the control driver to drive one of the metal lines to trigger a level shifting event in each of the first to the Kth scan periods, so that a level shifting event is correspondingly triggered on a scan line and a metal line in each of the first to the Kth scan periods.
According to another alternate embodiment of the present invention, a driving method applied in the display is provided. The display includes a first substrate, a second substrate, a scan driver, a data driver and a control driver. The first substrate has a common electrode. The second substrate includes M scan lines, N data lines, M control lines and MxN pixels, wherein M and N are natural numbers greater than 1. Each of the MxN pixels includes a first sub-pixel and a second sub-pixel. The second sub-pixel further has a discharge switch. The driving method includes the following steps of: applying the scan driver to provide M scan signals to drive M scan lines in the M scan periods respectively; applying the data driver to provide a data voltage to each of the N data lines in each of the M scan periods; applying the control driver to drive the first to the (M−K)th of the M control lines to provide (M−K) control signals in the (K+1)th to the Mth scan periods respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)th control lines; and applying the control driver to drive the second to the Kth of the M control lines to trigger level shifting events in the first to the (K−1)th scan periods respectively, so that level shifting events are triggered on a scan line and a control line in the first to the (K−1)th scan periods.
The above and other aspects of the invention will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment(s). The following description is made with reference to the accompanying drawings.
In the display of the present embodiment, a plurality of metal lines capable of forming equivalent capacitance with a common electrode is disposed on a second substrate. By triggering voltage level shifting events on the metal lines, substantially the same capacitance coupling events are triggered with respect to the common electrode in all scan periods, so that the common electrode has stable voltage level in all scan periods.
Referring to
Referring to
Each of the M×N pixels P(1,1)˜P(M,N) substantially has a similar circuit structure. The structures of the MxN pixels P(1,1)˜P(M,N) are exemplified by an (i,j)th pixel P(i,j), wherein i and j respectively are a natural number smaller than or equal to M and a natural number smaller than or equal to N.
Referring to
The sub-pixel PD is electrically connected to the scan line S_i, the data line D_i and the control line C_i, and includes a charge switch Q2, a discharge switch Q3, a liquid crystal capacitor CLC2 and a discharge capacitor CS. For example, the charge switch Q2 and the discharge switch Q3 may also be implemented by a TFT. In the charge switch Q2, the first source/drain is coupled to the data line D_i, the second source/drain is coupled to the liquid crystal capacitor CLC2, and the gate end is coupled to the scan line S_i. In the discharge switch Q3, the first source/drain is coupled to liquid crystal capacitor CLC2, the second source/drain is coupled to the discharge capacitor CS, and the gate end is coupled to the control line C_i.
For the pixel P(i,j), the charge switches Q1 and Q2 are enabled in response to an enabled scan signal Ssi (provided on the scan line S_i) for storing a data voltage on the data line D_j to the liquid crystal capacitors CLC1 and CLC2. The discharge switch Q3 is enabled in response to an enabled control signal Sci (provided on the control line C_i) for sharing charges on the liquid crystal capacitor CLC2 to the discharge capacitor CS.
Referring to
The control driver 13 is electrically connected to each of the M control lines C—1—C_M for providing enabled control signals Sc1˜ScM-K to drive the first to the (M−K)th control lines C—1˜C_(M−K) in the (K+1)th to the Mth scan periods TP_K+1˜TP_M respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)th control lines C—1˜C_M−K, wherein K is a natural number smaller than or equal to M. The control driver 13 further drives one of the metal lines DL1 and DL2 to trigger a level shifting event in each of the first to the Kth scan periods TP—1˜TP_K.
Referring to
The control driver 13 provides enabled control signals Sc1˜Sc(M−K) (corresponding to high signal levels) in scan periods TP_K+1˜TP_M respectively, and provides non-enabled control signals ScK+1˜ScM (corresponding to low signal level) in scan periods other than scan periods TP_K+1˜TP_M. The control signals ScM-K+1˜ScM continuously are non-enabled in scan periods TP—1˜TP_M. In other words, for each of the pixels P(1,1)˜P(M−K,N) on the first to the (M−K)th pixel rows of the display panel 11, the charge switches Q1 and Q2 write corresponding data voltages to the liquid crystal capacitors CLC1 and CLC2. In K scan periods after corresponding data voltages are written to the liquid crystal capacitors CLC1 and CLC2, the discharge switch Q3 is turned on in response to corresponding control signals to share charges on the liquid crystal capacitor CLC2 to the discharge capacitor CS. Since the sub-pixels PL and PD of each of the pixels P(1,1)˜P(M−K,N) on the first to the (M−K)th pixel rows correspond to different data voltages, the sub-pixels PL and PD have different liquid crystal inclination angles and the low color shift (LCS) display technology is correspondingly implemented.
For each of the pixels P(M−K+1,1)˜P(M,N) on the (M−K+1)th to the Mth pixel rows of the display panel 11, its corresponding control signals ScM−K+1˜ScM are continuously non-enabled in scan periods TP—1˜TP_M. Thus, each of the pixels P(M−K+1,1)-P(M,N) on the (M−K+)th to the Mth pixel rows substantially is not designed to perform the abovementioned charge operation between the liquid crystal capacitor CLC2 and the discharge capacitor C.
Under the abovementioned driving operation of the control driver 13, level shifting event occurs on only one metal wire (corresponding to scan line S—1 to S_K) in each of the scan periods TP—1˜TP_K, but occurs on two metal wires concurrently (corresponding to scan lines S_K+1˜S_M and control lines C—1˜C_M−K) in each of the scan periods TP_K+1˜TP_M. In addition, the scan lines or the control lines and the common electrode 112a may be equivalently used as a parasitic capacitor, and the voltage level shifting events triggered thereon correspondingly affect the voltage level on the common electrode 112a through the capacitance coupling effect.
In terms of the display 1 of the present embodiment, the number of metal wires (that is, only one metal wire) on which level switching event occurs in scan periods TP—1˜TP_K is not equal to the number of metal wires (that is, two metal wires) on which level switching event occurs in periods TP_K+1˜TP_M. Thus, the common electrode 112a face different intensities of capacitance coupling effect in the two sets of scan periods disclosed above, and accordingly correspond to different voltage levels. Thus, the brightness in the first to the Kth pixel rows of the display 1 will be different from the brightness in the (K+1)th to the Mth pixel rows, hence resulting in band mura as illustrated
To resolve the above band mura problem which jeopardizes display quality, the control driver 13 of the present embodiment drives one of the metal lines DL1 and DL2 to trigger a level shifting event in each of the first to the Kth scan periods TP—1˜TP_K. In the example illustrated in
In comparison to a conventional display, the display 1 of the present embodiment controls the common electrode 112a to continuously have substantially the same voltage level, so that band mura is correspondingly eliminated and display quality is effectively improved.
Let an operating example be taken for example, a ratio of parameter K to parameter M of the present embodiment is substantially greater than or equal to 1/1000 and smaller than or equal to 1/5, and the value of K is adjustable. In an operating example with the parameter M being equal to 1080, the value of parameter K is substantially greater than 2 and substantially smaller than or equal to 216.
Let another operating example be taken for example. The control driving circuit 13 of the present embodiment is controlled by the timing sequence controller 15 to determine the timing sequence in the scan periods TP—1˜TP_M.
In the present embodiment, the display panel 11 has two metal lines DL1 and DL2. However, the display 1 of the present embodiment is not limited to the above exemplification. In other examples, the display of the present embodiment may selectively have three or more than three metal lines disposed on the display panel, and the position of the metal lines is not limited to the underneath of the display panel. For example, the metal lines can be disposed in any part of the non-opening area covered by the common electrode.
Referring to
Referring to
Thus, the display 1′ of the present embodiment may trigger substantially the same capacitance coupling event with respect to the common electrode in each of the scan periods, so that the common electrode maintains stable voltage level over all scan periods.
Referring to
In each of the scan periods TP—1˜TP_K−1, the control driver of the present embodiment further drives the second to the Kth control lines C—2˜C_K of the M control lines C—1˜C_M to trigger level shifting events in the first to the (K−1)th scan periods TP—1˜TP_K−1 respectively. For example, the control driver of the present embodiment enables control signals Cs′2˜Cs′K in the first to the (K−1)th scan periods TP—1˜TP_K−1 to correspondingly drive the control lines C—2˜C_K to trigger level shifting events in corresponding scan periods TP1˜TP_K−1 respectively.
For the pixels on the rows correspondingly controlled by the control lines C—2˜C_K (that is, pixels P(2,1)˜P(K,N) on the second to the Kth rows of the display panel 11′), the enable periods (scan periods TP—1˜TP_K−1) of the control signals Cs′2˜Cs′K received by the pixels are triggered prior to the enable periods (scan periods TP—2˜TP_K) of the scan signals Ss2˜SsK received by the pixels. In other words, apart from the LCS operation as disclosed in the first embodiment, the pixels P(2,1)˜P(K,N) on the second to the Kth rows are further designed to perform a pre-LCS operation before the data scanning operation is performed.
By performing the pre-LCS operation on pixels P(2,1)˜P(K,N) on the second to the Kth rows by the driving controller of the present embodiment, level shifting events are triggered on two metal wires in any of the scan periods TP—1˜TP_K−1 and TP_K+1˜TP_M. Thus, in each of M scan periods TP—1˜TP_K−1 and TP_K+1˜TP_M, the common electrode 112a receives substantially the same capacitance coupling effect, and accordingly maintains substantially the same voltage level over the scan periods TP—1˜TP_K−1 and TP_K+1˜TP_M.
Let an operating example be taken for example. The driving controller of the present embodiment further drives the first control line C_1 of the M control lines to trigger a level shifting event in the pre-operation period TPx prior to the first scan period TP—1. In other words, pixels P(1,1)˜P(1,N) on the first row of the display panel 11′ of the present embodiment are also designed to perform the pre-LCS operation.
In the present embodiment, the driving controller performs a pre-LCS operation on the pixels P(2,1)˜P(K,N) on the second to the Kth rows in each of the scan periods TP—1˜TP_K, wherein the scan periods TP—1˜TP_K are one period prior to the scan periods TP—2˜TP_K corresponding to the pixels P(2,1)˜P(K,N) on the second to the Kth rows. However, the driving controller of the present embodiment is not limited thereto. In other examples, the driving controller may also perform the pre-LCS operation on the pixels two or more than two periods prior to the original scan periods corresponding to the pixels.
While the invention has been described by way of example and in terms of the preferred embodiment(s), 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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101120319 | Jun 2012 | TW | national |