Display and driving method thereof

A driving method applied in a display is provided. The display includes M scan lines, N data lines, M control lines and M×N pixels. M and N are natural numbers greater than 1. The driving method includes the following steps of: driving M scan lines in M scan periods respectively; providing a data voltage to each of the N data lines in each of the M scan periods; driving 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; and driving the second to the Kth 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 and control lines in the first to the (K−1)th scan periods.

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.

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE INVENTION

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 lines are disposed on the second substrate and correspond to the common electrode. The (i,j)thof the M×N pixels includes a first sub-pixel and a second sub-pixel. The first sub-pixel is electrically connected to the ithscan line and the jthdata 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)thcontrol lines in the (K+1)thto the Mthscan periods respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)thcontrol lines. The control driver further drives one of the metal lines to trigger a level shifting event in each of the first to the Kthscan 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 Kthscan 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 M×N pixels, wherein M and N are natural numbers greater than 1. The (i,j)thof the M×N pixels includes a first sub-pixel and a second sub-pixel. The first sub-pixel is electrically connected to the ithscan line and the jthdata 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 ithscan line, the jthdata line and the ithcontrol 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)thof the M control lines in the (K+1)thto the Mthscan periods respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)thcontrol lines. The control driver further drives the second to the KthM control lines to trigger level shifting events in the first to the (K−1)thscan periods respectively, so that level shifting events are triggered on a scan line and a control line in the first to the (K−1)thscan 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 M×N 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)thof the M control lines in the (K+1)thto the Mthscan periods respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)thcontrol 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 Kthscan 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 Kthscan 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 M×N pixels, wherein M and N are natural numbers greater than 1. Each of the M×N 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)thof the M control lines to provide (M−K) control signals in the (K+1)thto the Mthscan periods respectively to turn on the discharge switch in each of the pixels on the first to the (M−K)thcontrol lines; and applying the control driver to drive the second to the Kthof the M control lines to trigger level shifting events in the first to the (K−1)thscan periods respectively, so that level shifting events are triggered on a scan line and a control line in the first to the (K−1)thscan periods.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

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 toFIG. 1, a block diagram of a display according to a first embodiment of the invention is shown. The display1of the present embodiment, realized by such as an active matrix liquid crystal display (LCD) device, includes a display panel11, a scan driver12, a control driver13, a data driver14and a timing sequence controller15.

Referring toFIGS. 2A and 2B, a top view of a display panel11according to a first embodiment of the invention and a cross-sectional view of a display panel11along cross-sectional line A-A′ are respectively shown. The display panel11includes a first substrate112and a second substrate114. The first substrate112has a common electrode112a. The second substrate114includes an opening area114ain which M scan lines S_1˜S_M, N data lines D_1˜D_N, M control lines C_1˜C_M and M×N pixels P(1,1)˜P(M,N) are disposed, wherein M and N are natural numbers greater than 1. The second substrate114further includes a blocking area114bin which metal lines DL1and DL2are disposed. The blocking area114bis disposed on the second substrate114and corresponds to the common electrode112a. Furthermore, metal lines DL1and DL2are substantially covered by the common electrode112a.

Each of the M×N pixels P(1,1)˜P(M,N) substantially has a similar circuit structure. The structures of the M×N pixels P(1,1)˜P(M,N) are exemplified by an (i,j)thpixel 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 toFIG. 3, a schematic diagram of pixel P(i,j) according to a first embodiment of the invention is shown. The pixel P(i,j) includes sub-pixels PLand PD. The sub-pixel PLis electrically connected to the scan line S_i and the data line D_i, and includes a charge switch Q1and a liquid crystal capacitor CLC1. For example, the charge switch Q1is implemented by a thin film transistor (TFT) whose first source/drain is coupled to the data line D_i, second source/drain is coupled to the liquid crystal capacitor CLC1, and gate end is coupled to the scan line S_i.

The sub-pixel PDis 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 CLC2and a discharge capacitor CS. For example, the charge switch Q2and the discharge switch Q3may 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 Q1and Q2are 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 CLC1and CLC2. The discharge switch Q3is enabled in response to an enabled control signal Sci (provided on the control line C_i) for sharing charges on the liquid crystal capacitor CLC2to the discharge capacitor CS.

Referring toFIG. 1again. The scan driver12is electrically connected to each of the M scan lines S_1˜S_M for providing M scan signals Ss1˜SsM to drive M scan lines S_1˜-S_M in M scan periods TP_1˜TP_M respectively. The data driver14is electrically connected to N data lines D—1˜D_N for providing data voltages Sd1˜SdN to each of the N data lines D_1˜D_N in each of M scan periods TP_1˜TP_M.

The control driver13is 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)thcontrol lines C_1˜C_(M−K) in the (K+1)thto the Mthscan 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)thcontrol lines C_1˜C_M−K, wherein K is a natural number smaller than or equal to M. The control driver13further drives one of the metal lines DL1and DL2to trigger a level shifting event in each of the first to the Kthscan periods TP_1˜TP_K.

Referring toFIG. 4, related signal timing diagrams of a display1according to a first embodiment of the invention are shown. Furthermore, the scan driver12provides enabled scan signals Ss1˜SsM (corresponding to high signal level) in scan periods TP_1˜TP_M respectively, and provides non-enabled scan signals Ss1˜SsM (corresponding to low signal levels) in scan periods other than TP_1˜TP_M. In addition, in each of scan periods TP_1˜TP_M, the data driver14further correspondingly provides data voltages Sd1˜SdN to each of the N data lines D_1˜D_N for writing corresponding data voltages to pixels on the corresponding pixel row. Suppose each pixel has a circuit diagram as indicated inFIG. 3. The charge switches Q1and Q2are turned on in response to the enabled scan signals for storing corresponding data voltages to the liquid crystal capacitors CLC1and CLC2.

The control driver13provides 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)thpixel rows of the display panel11, the charge switches Q1and Q2write corresponding data voltages to the liquid crystal capacitors CLC1and CLC2. In K scan periods after corresponding data voltages are written to the liquid crystal capacitors CLC1and CLC2, the discharge switch Q3is turned on in response to corresponding control signals to share charges on the liquid crystal capacitor CLC2to the discharge capacitor CS. Since the sub-pixels PLand PDof each of the pixels P(1,1)˜P(M−K,N) on the first to the (M−K)thpixel rows correspond to different data voltages, the sub-pixels PLand PDhave 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)thto the Mthpixel rows of the display panel11, 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+)thto the Mthpixel rows substantially is not designed to perform the abovementioned charge operation between the liquid crystal capacitor CLC2and the discharge capacitor Cs.

Under the abovementioned driving operation of the control driver13, level shifting event occurs on only one metal wire (corresponding to scan line S_1to 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 electrode112amay be equivalently used as a parasitic capacitor, and the voltage level shifting events triggered thereon correspondingly affect the voltage level on the common electrode112athrough the capacitance coupling effect.

In terms of the display1of 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 electrode112aface 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 Kthpixel rows of the display1will be different from the brightness in the (K+1)thto the Mthpixel rows, hence resulting in band mura as illustratedFIG. 5. InFIG. 5, the first to the Kthpixel rows of the display1are denoted by “/” and the (K+1)thto the Mthpixel rows are denoted by “+”.

To resolve the above band mura problem which jeopardizes display quality, the control driver13of the present embodiment drives one of the metal lines DL1and DL2to trigger a level shifting event in each of the first to the Kthscan periods TP_1˜TP_K. In the example illustrated inFIG. 4, a level shifting event is triggered on the metal line DL1in odd-numbered scan periods of the scan periods TP_1˜TP_K, and is triggered on the metal line DL2in even-numbered scan periods of the scan periods TP_1˜TP_K. Through the driving operation of the control driver13, level shifting events are triggered on two metal lines in any of the M scan periods TP_1˜TP_M, so that the common electrode112areceives substantially the same capacitance coupling effect and accordingly maintains substantially the same voltage level over the M scan periods TP_1˜TP_M.

In comparison to a conventional display, the display1of the present embodiment controls the common electrode112ato 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 circuit13of the present embodiment is controlled by the timing sequence controller15to determine the timing sequence in the scan periods TP_1˜TP_M.

In the present embodiment, the display panel11has two metal lines DL1and DL2. However, the display1of 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 toFIG. 6, a flowchart of a driving method according to a first embodiment of the invention is shown. Detailed descriptions of each step of the driving method of the present embodiment are already disclosed in above passages, and are not repeated here.

Second Embodiment

Referring toFIG. 7, a schematic diagram of a display panel according to a second embodiment of the invention is shown. The display of the present embodiment is different from the display1of the first embodiment in that the display panel11′ does not have any metal lines, and the display of the present embodiment adjusts the wave-patterns of the control signals Cs′1˜Cs′M−K to have additional level shifting events triggered on partial or all of the control lines C_1˜C_M−K in each of the scan periods TP_1˜TP_K.

Thus, the display1′ 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 toFIG. 8, related signal timing diagrams of a display according to a second embodiment of the invention are shown. Over the scan periods TP_1˜TP_M, the operations performed by the scan driver and the data driver of the display of the present embodiment are substantially the same with that performed by corresponding drivers of the first embodiment. Over the scan periods TP_K+1˜TP_M, the operations performed by the control driver of the display of the present embodiment are substantially the same with that performed by the control driver13of the first embodiment. Therefore, operations performed by the scan driver and the data driver of the present embodiment are the same with that performed by corresponding drivers of the first embodiment, and are not repeated here.

In each of the scan periods TP_1˜TP_K−1, the control driver of the present embodiment further drives the second to the Kthcontrol 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)thscan 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)thscan 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 Kthrows of the display panel11′), 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 Kthrows 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 Kthrows 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 electrode112areceives 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_1of 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 panel11′ 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 Kthrows 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 Kthrows. 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.