Embodiments of the present disclosed technology relate to a driving device and a driving method for a liquid crystal display (LCD).
A phenomenon of motion blur, which is known as “image trialing” or “after image”, will occur when a general thin film transistor liquid crystal display (TFT-LCD) displays a fast moving image. Generally, it refers to a phenomenon in which the edge of the profile of the image blurs in the image transition process. There are two reasons for the occurrence of the phenomenon of the motion image blur, one of which is the excessive long response time of the liquid crystal (LC), and the other of which is the manner of keeping on driving of the thin film transistor (TFT).
Currently, the frequency doubling technology is mostly used to raise the frame frequency from 60 Hz to 120 Hz, in which black frames or motion compensation frames are interpolated between the original frames to prevent the occurrence of the motion blur phenomenon when the liquid crystal display displays a fast moving image. In the frequency doubling technology, it requires a memory with a relatively large storage capacity, and thus of a relatively high cost. Therefore, how to improve the motion blur phenomenon occurring when the TFT-LCD displays a fast moving image with a low cost is an urgent problem to be solved.
The present disclosure provides a driving device and a driving method for a liquid crystal display, which realizes the improvement of the motion blur phenomenon occurring when the TFT-LCD displays a fast moving image with a low cost.
An embodiment of the disclosed technology provides a driving device for a liquid crystal display, which is used for liquid crystal display of a charge sharing mode and comprises a control device for controlling the gates on the gate line to be turned on in a black frame insertion timing. Each gate line of the liquid crystal display is connected with the control device. The control device outputs to a gate line connected thereto a first control signal for controlling gates on the gate line to be turned on in a black frame insertion timing, wherein the black frame insertion timing is timing when charge sharing is conducted among data lines from the gates on the gate line are turned off in the current frame until they are turned on in the next frame.
In an example, the control device comprises an AND gate, the first input terminal of which is connected to a timing controller, and the second input terminal of which is connected to a gate turn-on signal output terminal, and the AND gate provides the first control signal to its corresponding gate line according to a first timing signal input from the timing controller and the gate turn-on signal input from the gate turn-on signal output terminal.
Further, in an example, in order to save cost, the control device connected to each gate line comprises an OR gate, the first input terminal of which is connected to the output terminal of the AND gate, the second input terminal of which is connected to a output terminal for providing a second control signal to each gate line, and the output terminal of the OR gate is connected to its corresponding gate line. The second control signal controls the gates on each gate lines to be turned on row by row in a charge sharing mode, and the first timing signal is a timing signal for controlling the charge sharing act.
Another embodiment of the disclosed technology provides a driving method for a liquid crystal display, which is used for a liquid crystal display of a charge sharing mode, comprises: inputting a driving voltage for turning on a gate to the gate line of the L-th row in a black frame insertion timing, which is timing when charge sharing is conducted among data lines from the gates on the gate line of the L-th row are turned off in the current frame until they are turned on in the next frame, wherein, 1<L≦N, N is the total number of the gate lines of the liquid crystal display panel, and L is an integer.
In an example, the step of inputting a driving voltage for turning on a gate to the gate line of the L-th row in the BFI time comprises: after the gates on the gate line of the (M−1)-th row are turned off, and before the gates on the gate line of the M-th row are turned on, inputting the driving voltage for turning on a gate to the gate line of the L-th row, turning on the gate line of the L-th row, and neutralizing the source data of the L-th row of the liquid crystal display panel by charge sharing to become a common electrode voltage; wherein, 1≦M≦N, N is the total number of the gate lines of the liquid crystal display panel, M is an integer, and the gate line of the M-th row is the gate line whose gate is turned on after the gate line of the L-th row.
In the driving device and the driving method for the liquid crystal display provided by the embodiments of the present disclosed technology, in the condition of charge sharing among data lines, gate line of each row of the liquid crystal display is turned on in its corresponding black frame insertion timing, the source data corresponding to gate line of each row of the liquid crystal display panel is neutralized in the black frame insertion timing to approximate the common electrode voltage, so that the display effect of this row is equivalent to that when black data is inserted. In this way, the gate line of a row has displayed a black image for a period of time when the source data corresponding to this row arrives in the next frame, thereby realizing the screen-refreshing effect and improving the motion blur phenomenon of the liquid crystal display panel.
Further scope of applicability of the present disclosed technology will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosed technology, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosed technology will become apparent to those skilled in the art from the following detailed description.
The present disclosed technology will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present disclosed technology and wherein:
a) is a structural schematic diagram of a charge sharing device in the liquid crystal display shown in
b) is a timing chart for realizing charge sharing in the liquid crystal display shown in
a) is a second circuit diagram of the control device in the liquid crystal display shown in
b) is a timing chart for the liquid crystal display shown in
a) is a second circuit diagram of the control device in the liquid crystal display shown in
b) is a timing chart for the liquid crystal display shown in
In the following, the technical solutions of the embodiments of the present disclosed technology will be described clearly and thoroughly with reference to the figures for the embodiments of the present disclosed technology. Obviously, the described embodiments are only a part of, but not all, embodiments of the present disclosed technology. All other embodiments obtained based on the embodiments of the present disclosure by those of ordinary skill in the art without inventive labor shall fall within the protection scope of the present disclosed technology.
In order to realize the improvement of the motion blur phenomenon occurring when a TFT-LCD displays a fast moving image with a low cost, the embodiments of the present disclosed technology provide a driving device and a driving method for a liquid crystal display.
As shown in
The driving device for the liquid crystal display further comprises control devices to control the gates on the gate lines to be turned on at the time of Black Frame Insertion (BM). Each gate line of the liquid crystal display panel is connected with the control device, which outputs a first control signal to the gate line connected thereto so as to control the gates on the gate line to be turned on in the BFI time. The BFI time is a time when the charge sharing is conducted among the data lines from the gates on the gate line is turned off in the current frame until they are turned on in the next frame and.
In particular, as shown in
The driving device for the liquid crystal display provided by the embodiment of the present disclosed technology is of a charge sharing mode, in which a charge sharing device is disposed at the source data output terminal of the source driver. It is possible for the charge sharing device to neutralize the source data output from the source data output terminal of the source driver to approximate the common electrode voltage when conducting charge sharing act. Then, on the basis of the charge sharing mode, each gate line of the liquid crystal display panel is made to be turned on in the corresponding BFI time. The source data corresponding to each gate line of the liquid crystal display panel is neutralized to approximate the common electrode voltage in the BFI time, so that the display effect of this row is equivalent to that when black data is inserted therein. In this way, the gate line of this row has displayed a black image for a period of time when the source data corresponding to this row arrives in the next frame, thereby realizing the screen-refreshing effect and improving the motion blur phenomenon of the liquid crystal display panel.
In order to make those skilled in the art better understand the liquid crystal display of a charge sharing mode provided by the embodiment of the present disclosed technology, a detailed description will be made hereinafter to the liquid crystal display of the charge sharing mode.
The liquid crystal display of the charge sharing mode provided by the embodiment of the present disclosed technology comprises the liquid crystal display panel, the timing controller, the source driver and the gate driver. The timing controller outputs the timing control signal to the source driver and the gate driver.
As shown in
In particular, as shown in
In
CPV is a clock signal provided by the timing controller, and used as a reference clock for signals such as TP, STV, OE and OUT1˜OUTn etc.
STV is a frame turn-on signal provided by the timing controller.
OE is a low level enabling signal provided by the timing controller. The rising edge of OE is before the rising edge of TP, and the falling edge of OE is after the falling edge of TP.
OUT1˜OUTn provided by the gate driver are the gate turn-on signals for the first row to the last row, and are output from the gate turn-on signal output terminal of the gate driver.
Now, as an example, descriptions will be made with reference to a case in which the charge sharing act is conducted before the gate line of the fourth row is ready to be selected sequentially after the gate line of the third row has been selected sequentially. The rising edge of TP controls the charge sharing device to start conducting the charge sharing act. OUT3 and OUT4 provide gate turn-on signals to the gate lines of the third row and the fourth row. In order to prevent the source data on the gate line of the third row from being washed out due to the charge sharing act and the image quality from being affected due to the non-readiness of the source data on the gate line of the fourth row, the driving signals G3 and G4 output from the output terminals of the gate drivers are obtained from OE in combination with OUT3 and OUT4. In particular, as shown in
G3=OUT3*
With reference to
Therefore, the gates on the gate line of the third row will be turned off in advance at the rising edge of OE, to avoid the gates on the gate line of the third row not being turned off when the charge sharing act starts and thereby the source data of the third row of the liquid crystal display panel being washed out, wherein the source data of the third row is provided by the source driver.
Also, the turning on of the gate on the gate line of the fourth row is delayed at the falling edge of OE, to ensure that the gate on the gate line of the fourth row will not be turned on until the charge sharing act is over and the source driver has output valid source data. In this way, the valid source data has been ready and input to the liquid crystal display when the gate on the gate line of the fourth row is turned on, thereby guaranteeing the image quality.
It can be known from OUT3 and OUT4 that all gates are turned off during the charge sharing period, i.e. the period when the corresponding TP is of a high level. Therefore, only the charge sharing is conducted at the output terminal of the source driver, and the drains of the TFTs are not affected, that is, the stored data of the liquid crystal display panel is not affected.
The above is only one of the charge sharing technologies. On the basis of the above charge sharing technology, a liquid crystal display of a charge sharing mode provided by another embodiment of the present disclosed technology is configured with a source driver, a gate driver, a timing controller, a control device and a liquid crystal display panel, as shown in
In the present embodiment, the above mentioned OE, TP, STV, OE and CPV signals are provided by the timing controller. Preferably, the TP signal, the OE signal and the gate turn-on signal provided by the timing controller provide the gate line selection signals G1˜GN to the gate lines G1˜GN through the control devices. The control devices can be disposed outside of the driver, or alternatively inside of the driver. In particular, it can be implemented by the logic gate circuits as shown in
G
L=OUTL*
The control device comprises an AND gate and an OR gate. The first input terminal of the AND gate is connected to the signal output terminal of the timing controller for controlling the charge sharing act among the data lines. In the present embodiment, the signal output terminal of the timing controller for controlling the charge sharing act among the data lines is the TP signal output terminal. The second input terminal of the AND gate is connected to the gate turn-on signal output terminal of the M-th row of the gate driver, which outputs a signal of OUTM for controlling the gates on the gate line of the M-th row to be turned on. The output terminal of the AND gate is connected to the first input terminal of the OR gate. The second input terminal of the OR gate is connected to the second control signal output terminal of the L-th row of the gate driver, the second control signal output terminal of the L-th row outputting a signal of OUTL*
Now a detailed description will be made to the setting of the time t2, which comprises, but not limited to, the following implementation.
(1) As shown in
(2) As shown in
It is to be noted that, in the implementation (2), the charge sharing act is conducted to gate lines of other adjacent two rows every other row. However, in a particular implementation, the charge sharing act can be conducted to gate lines of other adjacent three rows every two rows, or alternatively to gate lines of other adjacent four rows every three rows, and so on. The details will not be described here. The more the gate lines to which the charge sharing is conducted simultaneously every time, the less the logic gates it requires. On the other hand, in the implementation (2), the charge sharing act can be conducted multiple times in a particular implementation. For example, the gates on the gate lines of the first and the second gate lines are turned on for charge sharing before the m-th row is about to display after the (m−1)-th row has displayed; and the gates on the gate lines of the first and the second gate lines are turned on again before the (m+1)-th row is about to display after the m-th row has displayed. Since the TP time (i.e., the charge sharing time) is relatively short, the stored charge may not be neutralized completely in one time; therefore neutralization can be assured by conducting the charge sharing act many times.
In the above mentioned implementations (1) and (2), the BFT time t2 can be set by setting the value of m as required. The large the value of m is, the longer the keep time of the data of the last frame is, and the shorter the keep time of the black data is. Generally, the keep time of the data of the last frame should be increased as much as possible provided that the screen-blacking effect is guaranteed. Here, it can be realized by only adding one stage of logic gate circuits to the output terminal of the gate driver, and referring to the signal output from the timing controller and the gate turn-on signal output from the gate turn-on signal output terminal in the gate driver. The configuration is simple, and the purpose of improving motion blur phenomenon occurring when the TFT-LCD displays the fast moving image with a low cost is achieved.
The driving method for the liquid crystal display provided by the embodiment of the present disclosed technology is used for the liquid crystal display in the charge sharing mode, comprising:
inputting a driving voltage for turning on a gate to a gate line of the L-th row in a BFI time, which is a time when charge sharing is conducted among the data lines from the gates on the gate line of the L-th row are turned off in the current frame until they are turned on in the next frame, wherein 1<L≦N, N is the total number of the gate lines of the liquid crystal display panel, and L is an integer.
In particular, the step of inputting a driving voltage for turning on the gate to the gate line of the L-th row in the BFI time comprises:
after the gates on the gate line of the (M−1)-th row are turned off, and before the gates on the gate line of the M-th row are turned on, inputting the driving voltage for turning on the gate to the gate line of the L-th row, turning on the gate line of the L-th row, and neutralizing the source data of the L-th row of the liquid crystal display panel by charge sharing to become the common electrode voltage;
wherein, 1≦M≦N, N is the total number of the gate lines of the liquid crystal display panel, M is an integer, and the gate line of the M-th row is the gate line whose gates are turned on after the gate line of the L-th row.
The driving method for the liquid crystal display provided by the embodiment of the present disclosed technology is of a charge sharing mode, in which a charge sharing device is disposed at the source data output terminal of the source driver. It is possible for the charge sharing device to neutralize the source data output from the source data output terminal of the source driver to approximate the common electrode voltage when conducting the charge sharing act. Then, on the basis of the charge sharing mode, the gate line of each row of the liquid crystal display panel is made to conduct charge sharing in the corresponding BFI time. The source data corresponding to the gate line of each row of the liquid crystal display panel is neutralized to approximate the common electrode voltage, so that the display effect of this row is equivalent to black data. In this way, the gate line of the row has displayed a black image for a period of time when the source data corresponding to this row arrives in the next frame, thereby realizing the screen-refreshing effect and improving the motion blur phenomenon of the liquid crystal display panel.
The liquid crystal display of the charge sharing mode and the driving method therefor provided by the embodiments of the present disclosed technology can be applied in the liquid crystal display of a normally black mode.
The above are only particular implementations of the present disclosed technology. Nevertheless, the protection scope of the present disclosed technology is not limited thereto. Those skilled in the art can conceive variations or alternations easily within the technical scope disclosed by the present disclosure, and such variations or alternations should fall within the protection scope of the present disclosed technology. Therefore, the protection scope of the present disclosed technology should be defined by the claims.
Number | Date | Country | Kind |
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201110004038.2 | Jan 2011 | CN | national |