JPH04329592A - Method and device for driving liquid crystal panel - Google Patents

Abstract

PURPOSE:To obtain the inveriably proper effect of laterla tailing removal even when a cell has different characteristics as to the method and device for diriving the liquid crystal panel in simple matrix structure. CONSTITUTION:This method is the driving method for the liquid crystal panel which drives the simple matrix type liquid crystal panel equipped with data electrode and scanning electrode by employing a voltage averaging method, and a correction voltage of level coresponding to the light and dark ratio of data to be displayed on selected scanning electrodes is determined at each time one-scan electrode driving is performed; and this correction voltage is added to a liquid crystal cell aplied voltage while a positive voltage application mode period and a negative voltage application mode period are opposite in polarity, each other. The driving method and device for the liquid crystal panel are constituted by providing a weighting circuit 10 which weights display data corresponding to the characteristics of the liquid crystal cell to a correction parameter generating circuit 7.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION The present invention relates to a method and device for driving a liquid crystal panel with a simple matrix structure, and more particularly to a method and device for driving a liquid crystal panel that always appropriately removes display unevenness even when cell characteristics differ. Regarding. In recent years, with the spread of personal computers, word processors, etc., liquid crystal displays (LCDs), which are lightweight, thin, and can be powered by batteries, have been increasingly adopted as display devices in place of CRTs, which are large and consume a lot of power. LCD driving methods are broadly divided into simple matrix type and active matrix type, but active matrix type is difficult to manufacture because it requires a nonlinear element for each pixel, and currently LCDs with large display capacity generally use A simple matrix structure is adopted.

However, due to the characteristics of display devices with a simple matrix structure, as the display capacity is increased, display pattern-dependent display unevenness (crosstalk) occurs and display quality deteriorates, so countermeasures against this problem are strongly desired. .

0003

2. Description of the Related Art FIG. 5 shows that when "bright" is written to all the liquid crystal display elements in one row such as columns X1 and X2 in a liquid crystal panel having a simple matrix structure shown in FIG.
The driving waveforms of the liquid crystal panel are shown when the liquid crystal display is ○) and when "dark" writing is performed (the liquid crystal display is ●). In FIG. 5, (a) shows the data voltage application waveform in the X1 column (thick line) and the data voltage application waveform in the X2 column (dotted line), and (b) shows the scan voltage application waveform in the Y1 row, (
c) is the scan voltage application waveform of row Y2, and (d) is the drive voltage waveform of cell α (thick line) and the drive voltage waveform of cell β (dotted line).

[0004] The conventional driving method employs the voltage averaging method shown in FIG. 7, in which the first period is selected during one frame period, and the second period is selected in the next frame. In addition, devices in which the first period and the second period are switched every few lines are in practical use, and this prevents direct current components from being applied to the liquid crystal, achieving highly reliable driving that does not deteriorate panel characteristics.

FIG. 8 shows a configuration diagram of a conventional liquid crystal panel driving device. This conventional example is a device for driving a simple matrix type liquid crystal panel 83 equipped with a data electrode driver 81 and a scan electrode driver 82, and its configuration includes a positive voltage application mode period and a negative voltage application mode period for the data electrode driver 81. A power supply circuit 84 that provides a selection voltage and a non-selection voltage for a period, and a selection voltage and a non-selection voltage for a positive voltage application mode period and a negative voltage application mode period to a scan electrode driver 82, and a data signal to a data electrode driver 81. A control circuit 8 that also sends a scan signal to a scan electrode driver 82
5, a voltage polarity switching circuit 86 that switches between a positive voltage application mode period and a negative voltage application mode period in accordance with a signal from this control circuit 85; A correction parameter generation circuit 87 that measures the ratio of brightness and darkness of data to generate a correction parameter, a correction voltage generation circuit 88 that generates a correction voltage of a magnitude corresponding to this correction parameter, and a correction voltage generation circuit 88 that generates a correction voltage of a magnitude corresponding to the correction parameter. It consists of a correction voltage addition circuit 89 that adds to the scan voltage at the time of selection.

In the liquid crystal panel driving device of this conventional example, the amount of voltage level fluctuation of the liquid crystal cell applied waveform depending on the display pattern is determined for each line from the display pattern.
When there are many displays, the power supply circuit is controlled so that the selection voltage level of the scan electrode is raised in the first cycle and lowered in the second cycle. This suppresses display unevenness (horizontal trailing) caused by the scan electrode selection voltage level varying depending on the number of "bright" cells and "dark" cells on the same scan electrode.

[0007]

[Problems to be Solved by the Invention] However, in this conventional liquid crystal panel driving device, for example, R (red), G (green)
, B (blue) color filters, the amount of correction was calculated assuming that the R, G, and B cells have the same effect on horizontal trailing. In other words, if the display position is approximately the same, horizontal trailing to the same extent will occur whether the R cell is on or the G cell is on. However, in reality, since the color filters have different thicknesses, the liquid crystal layers have different thicknesses for R, G, and B, resulting in differences in cell characteristics.

Therefore, the effect on horizontal trailing is different for each R, G, and B cell. For example, even if only red is displayed and the horizontal trailing removal circuit is optimally adjusted, if only green is displayed,
There was a problem in that the adjustment was significantly off and horizontal tailing occurred. SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for driving a liquid crystal panel in the conventional simple matrix liquid crystal display device, which can always obtain an appropriate horizontal trailing removal effect even when cell characteristics differ. shall be.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the method for driving a liquid crystal panel of the present invention drives a simple matrix type liquid crystal panel equipped with data electrodes and scan electrodes using a voltage averaging method. A method of driving a liquid crystal panel in which a correction voltage of a magnitude corresponding to the ratio of brightness and darkness of data displayed on the selected scan electrode is determined for each scan electrode drive, and this correction voltage is applied in a positive voltage application mode. The liquid crystal panel driving method adds the voltage applied to the liquid crystal cell with opposite polarity during the period and the negative voltage application mode period, and is characterized by weighting the display data according to the characteristics of the liquid crystal cell.

FIG. 1 shows the configuration of a liquid crystal panel driving device according to the present invention that implements this method. The present invention scans a simple matrix liquid crystal panel 3 equipped with a data electrode driver 1 and a scan electrode driver 2 by applying a selection voltage and a non-selection voltage to the data electrode driver 1 during a positive voltage application mode period and a negative voltage application mode period. A power supply circuit 4 that provides a selection voltage and a non-selection voltage to the electrode driver 2 during a positive voltage application mode period and a negative voltage application mode period, and a data electrode driver 1
a control circuit 5 that sends a data signal to the scan electrode driver 2 and a scan signal to the scan electrode driver 2; and a voltage polarity switching circuit 6 that switches between a positive voltage application mode period and a negative voltage application mode period according to the signal from the control circuit 5. , a correction parameter generation circuit 7 that measures the ratio of brightness and darkness of data displayed on the selected scan electrode every scan electrode drive time and generates a correction parameter, and a correction voltage of a magnitude corresponding to the correction parameter. In a liquid crystal panel driving device that is driven by a correction voltage generation circuit 8 that generates a correction voltage and a correction voltage addition circuit 9 that adds this correction voltage to the scan voltage at the time of selection of the power supply circuit 4, the correction parameter generation circuit 7 includes a liquid crystal The present invention is characterized by the provision of a weighting circuit 10 that weights display data according to cell characteristics.

[0011]

[Function] In the liquid crystal panel driving device of the present invention, as shown in FIG. 1, the correction parameter generation circuit 7 is provided with a weighting circuit 10 for weighting display data according to the characteristics of the liquid crystal cell. Display data is weighted by giving different weight values depending on the capacity and color of the liquid crystal cell.

[0012] Therefore, an appropriate weight value can be given to each cell, and an appropriate horizontal trailing removal effect can always be obtained even when the characteristics of the cells are different.

[0013]

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, since the basic device configuration for driving the liquid crystal panel is the same as the device shown in FIG. 8, its explanation will be omitted. However, only the configuration of the correction parameter generation circuit, which is a feature of the present invention and differs in configuration from the conventional device, will be described.

First Embodiment FIG. 2 shows a first embodiment of the present invention. Figure 2(a) shows the cell arrangement of a liquid crystal panel that performs multi-gradation display by combining cells with different areas.Here, a cell with a large area is called an L cell, and a cell with a small area is called an S cell. call. Further, FIG. 2(b) shows a configuration diagram of a correction parameter generation circuit of a liquid crystal panel driving device according to the first embodiment of the present invention, and the same components as in FIG. 1 are given the same reference numerals. .

In FIG. 2(b), 21 is a binary counter circuit that counts data clock signals DCLK for synchronizing display data to generate a designated weighting value. 22 is a weighting circuit, and display data XDATA
And a weight value is generated based on the weighting designated value of the binary counter circuit 21. Reference numeral 23 denotes an integration circuit, which is reset by the horizontal synchronization signal SSYNC inputted to the reset input RST every one scan electrode selection period, integrates the weight value of the weighting circuit 22, and calculates the correction parameter every one scan electrode selection period. Occur. That is, in this embodiment, a binary counter circuit 21 that generates a designated weighting value is provided to synchronize the arrangement of data in the display data XDATA and the arrangement of cells on the liquid crystal panel, and provide weighting values with different characteristics. Configure it as follows.

The display data XDATA is a signal sent in a 1-bit format in which data indicating whether the cell is on or off is arranged in order from the leftmost cell, for example.
0 and 1 are output as weighting designation values corresponding to each cell, cell and S cell, respectively. With the above configuration, in this embodiment, the input display data XDATA is
A weighting circuit 22 determines whether it is a cell or an S cell.
makes a judgment and outputs the corresponding weight values WL and WS.

As a result, it becomes possible to accurately predict the degree of horizontal tailing that will occur, and appropriate correction becomes possible. Note that the arrangement of the L cells and S cells is not limited to the shape shown in FIG. 2(a). Moreover, although the case where there are two types of cells has been described as an example here, this is not limited to two types.

Second Embodiment FIG. 3 shows a second embodiment of the present invention. Figure 3(a) shows R(
This shows the cell arrangement of a multicolor display panel equipped with color filters of red), G (green), and B (blue).
They are arranged in the order of R, G, and B from the left. Further, FIG. 3(b) shows a configuration diagram of a correction parameter generation circuit of a liquid crystal panel driving device according to a second embodiment of the present invention, and the same components as in FIG. 1 are given the same reference numerals. .

In FIG. 3(b), display data XDAT
A is a signal that sends 4-bit data indicating whether each cell is on or off, for example, in groups of four cells starting from the leftmost cell (for example, R1, G1, B1, and R2 cells). The ternary counter circuit 31 stores R, G, and B in the display data XDATA.
0, 1, and 2 are output as weighting designation values corresponding to the three types of arrays, RGBR, GBRG, and BRGB, respectively. The weighting circuit 22 also includes a ternary counter circuit 3
It is sufficient to configure the memory with the weighting specified value (2 bits) by 1 as the upper address signal and the 4 bits of display data XDATA as the lower address signal. against GB
This can be achieved by storing each weight value of BRGB as data for RG and address 10××××B.

With the above-described configuration, in this embodiment, the weighting circuit 22 uses the input display data XDA
The arrangement of R, G, and B in TA is judged using the weighting designation value output from the ternary counter circuit 31, and the R, G, and B of each bit are determined.
Weight values of WR, WG, and WB are given to G and B, respectively, and the sum thereof is output as the weight value. As a result,
It is possible to deal with differences in the characteristics of each R, G, and B cell, and it becomes possible to accurately predict the degree of horizontal tailing that will occur, making it possible to perform appropriate correction.

[0021]Although this embodiment shows an example of a panel in which three colors, R, G, and B are arranged, this is not limited to R, G, and B, and is not limited to three colors. not. Third Embodiment FIG. 4 shows a third embodiment of the present invention. This figure shows a configuration diagram of a correction parameter generation circuit of a liquid crystal panel driving device according to a third embodiment of the present invention, and the same components as in FIG. 1 are given the same reference numerals.

In FIG. 4, display data XDATA is
An example is shown in which data indicating whether the cell is on or off is sequentially arranged and sent in one bit starting from the leftmost cell in the panel of FIG. 3(a). The ternary counter circuit 41 receives R in the display data XDATA.
, G, and B, the weighting designation values 0, 1, and 2 are output. Further, the coordinate counter circuit 44 inputs the data clock signal DCLK and outputs the coordinates on the scanning electrodes of the cell. The weighting circuit 22 receives the input display data XDA
For TA, WR, WG using the specified weighting value
, WB, weighting is performed based on the cell coordinates, and a weight value is output.

As a result, it is possible to deal with differences in the characteristics of each R, G, and B cell, and at the same time deal with differences in their display positions, making it possible to accurately predict the degree of horizontal tailing that will occur. Therefore, more appropriate correction becomes possible. In this embodiment, a ternary counter circuit 41 is provided to distinguish between R, G, and B;
The forward counter circuit 41 is abolished and the weighting circuit 22 is used instead.
It is also possible to have R, G, and B information corresponding to the cell coordinates in the cell coordinates, and weight the difference in cell characteristics and the difference in display position at the same time.

In the first to third embodiments, an example of a multi-color display panel was shown, but the present invention can also be similarly applied to panels in which cell characteristics differ due to differences in the orientation of liquid crystal molecules, etc. be able to.

[0025]

[Effects of the Invention] As explained above, according to the present invention,
The correction parameter generation circuit is provided with a weighting circuit that weights the display data according to the characteristics of the liquid crystal cell, and the display data is given a weight value of a different size depending on the capacitance of the liquid crystal cell and the color of the liquid crystal cell. By assigning weights to each cell, an appropriate weight value can be given to each cell, and as a result, even when the characteristics of the cells are different, the liquid crystal display always has an appropriate horizontal stripping removal effect. A driving device for the panel can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention.

FIG. 2(a) is a diagram showing the cell arrangement of the area gradation display panel, and FIG. 2(b) is a diagram showing the correction parameter generation of the liquid crystal panel driving device according to the first embodiment of the present invention. It is a block diagram of a circuit.

FIG. 3(a) is a diagram showing a cell arrangement of a color display panel, and FIG. 3(b) is a diagram showing a correction parameter generation circuit of a driving device for a liquid crystal panel according to a second embodiment of the present invention. FIG.

FIG. 4 is a configuration diagram of a correction parameter generation circuit of a liquid crystal panel driving device according to a third embodiment of the present invention.

FIG. 5 is a drive waveform diagram of cells α and β in FIG. 6;

FIG. 6 is a diagram showing an example of a display pattern on a liquid crystal panel.

FIG. 7 is a diagram showing a voltage averaging method.

FIG. 8 is a diagram illustrating the principle of a conventional liquid crystal panel driving device that eliminates display unevenness.

[Explanation of symbols]

1, 81...Data electrode driver 2, 82...Scan electrode driver 3, 83...LCD panel 4, 84...power supply circuit 5, 85...control circuit 6, 86...Voltage polarity switching circuit 7, 87...Correction parameter generation circuit 8, 88...Correction voltage generation circuit 9, 89...Correction voltage addition circuit 10, 22...Weighting circuit 21...Binary counter circuit 23... Integration circuit 31, 41...Ternary counter circuit 44...Coordinate counter circuit XDATA…display data DCLK...Data clock signal SSYNC...Horizontal synchronization signal

Claims (5)

[Claims] 1. A method for driving a liquid crystal panel, in which a simple matrix liquid crystal panel equipped with data electrodes and scan electrodes is driven using a voltage averaging method, the scan electrode being selected for each scan electrode drive. A liquid crystal display device that determines a correction voltage corresponding to the brightness/darkness ratio of the data displayed on the screen, and adds this correction voltage to the voltage applied to the liquid crystal cell with opposite polarity during the positive voltage application mode period and the negative voltage application mode period. A method for driving a liquid crystal panel, the method comprising weighting display data according to characteristics of a liquid crystal cell. 2. The method of driving a liquid crystal panel according to claim 1, wherein the display data is weighted according to the capacitance of the liquid crystal cell. 3. A method for driving a multicolor display liquid crystal panel in which a simple matrix type liquid crystal panel equipped with data electrodes and scan electrodes is driven using a voltage averaging method, wherein a selected color is selected for each scan electrode drive. A correction voltage of a magnitude corresponding to the ratio of brightness and darkness of data displayed on the scan electrode is determined, and this correction voltage is applied to the voltage applied to the liquid crystal cell with opposite polarity during the positive voltage application mode period and the negative voltage application mode period. 1. A method for driving a liquid crystal panel that performs summing, the method comprising weighting display data by giving different weight values to liquid crystal cells of each color. 4. The method of driving a liquid crystal panel according to claim 1, 2, or 3, further comprising weighting the display data according to the distance of the liquid crystal cell from the scan driver output, in addition to the method described above. 1. A method for driving a liquid crystal panel, characterized in that, when determining the magnitude of a correction voltage, the direction along a scan electrode is divided into a plurality of regions, and weighting is performed by setting the weight within the same region to a constant value. 5. A simple matrix type liquid crystal panel (3) equipped with a data electrode driver (1) and a scan electrode driver (2) is arranged such that the data electrode driver (1) has a positive voltage application mode period and a negative voltage application mode period. A power supply circuit (4) that supplies a selection voltage and a non-selection voltage to a scan electrode driver (2) during a positive voltage application mode period and a negative voltage application mode period, and a data electrode driver (1).
) and a control circuit (5) that sends a scan signal to the scan electrode driver (2), and a positive voltage application mode period and a negative voltage application mode period according to the signals from this control circuit (5). A voltage polarity switching circuit (6) to be switched, and 1
A correction parameter generation circuit (7) generates a correction parameter by measuring the ratio of brightness and darkness of data displayed on the selected scan electrode every scan electrode drive time, and a correction voltage of a magnitude corresponding to this correction parameter. A correction voltage generation circuit (8) that generates a correction voltage, and a correction voltage addition circuit (9) that adds this correction voltage to the scan voltage at the time of selection of the power supply circuit (4).
), wherein the correction parameter generation circuit (7) is provided with a weighting circuit (10) that weights display data according to characteristics of the liquid crystal cell. drive unit.