JPS5925228B2 - Driving method of liquid crystal display device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for driving a liquid crystal display device.

When dynamically driving a liquid crystal, crosstalk, that is, current looping occurs, causing display to be performed on other unnecessary display sections. To solve this problem, various driving methods have been devised in the past.

As an example, in the case of a matrix type display, the voltages applied in the row and column directions are distributed as shown in Tables A and B of FIG. According to this method, an alternating current voltage is applied to the liquid crystal at regular intervals, so it is excellent in extending the life of the liquid crystal. However, when looking at the voltage applied to the intersection of rows and columns, voltage -1/, υ is applied to the intersection that should respond with duty (number of digits - 1)/number of digits, and voltage is applied with duty 1/number of digits. υ is applied, but the voltage ``υ'' is always applied to the non-responsive intersection.However, when the duty of the liquid crystal decreases, the response voltage increases rapidly.Therefore, the non-responsive portion becomes non-responsive. The voltage must be greater than 1/3 υ, and the response voltage must be less than or equal to voltage υ.Taking these into consideration, the number of digits is limited to 4.This problem In order to solve this problem, it is possible to apply a high frequency signal to the non-responsive rows to erase them.

Although this solves the problem of crosstalk, it has the disadvantage of increasing the applied voltage. In other words, as the number of digits increases, the response voltage of the liquid crystal increases rapidly, resulting in a disadvantage that the high frequency voltage applied for erasing also increases. Therefore, the present invention takes advantage of the property that when a unipolar high-frequency pulse below the saturation voltage is continuously applied to a liquid crystal, it gradually responds, and applies the unipolar high-frequency pulse to the liquid crystal display element to be selected. A voltage of 0 or an alternating current high frequency pulse is applied to unselected liquid crystal display elements to make them non-responsive before the cumulative response is caused by a high frequency pulse.
This eliminates the above drawbacks.

An embodiment of the present invention will be described below based on the drawings.

In FIG. 2, reference numeral 1 denotes a timing signal generator that supplies timing signals of FIG. 3, which will be explained later, to row electrodes X1, X2, . . . , X7.

2 is a column electrode y,, y2, according to the data display content.
...This is a selection pulse generator that supplies high frequency pulses to y5.

Next, the pulse application method will be explained with reference to FIGS. 3 and 4.

The row electrodes Xl, X2... A high frequency pulse f1 is supplied at the time.

For example, when displaying the number "5", the pulses shown in FIG. 4 are supplied to the column electrodes Yl, y2, . . ., Y5. FIG. 5A shows the voltage applied between the row electrode X4 and column electrode y1 at this time, and FIG. 5A shows the voltage applied between the row electrode X5 and column electrode y1. Figure 5A. In the case of FIG. 5A, a unipolar high-frequency pulse is constantly applied, and the liquid crystal responds cumulatively, becoming completely responsive.

Therefore, display elements X4-y1 are displayed. In the case of FIG. 5B, since the voltage is held at the voltage 'O' for the time t1 of one period t, the liquid crystal returns to the non-responsive state before it makes a cumulative response.

Therefore, the display element X5-y1 is kept in a non-responsive state.
is not displayed. Similarly to the above, a unipolar high frequency pulse is constantly applied to a desired display element, it responds cumulatively, and maintains the responsive state after responding. Since the voltage applied to the other display elements becomes "O" during the time t1 of one cycle t, they are held in a non-responsive state.In this way, the hatched part shown in the second diagram is displayed, and the "5" ” is displayed. 6th,
FIG. 7 shows another example of voltage application.

In Figure 6, the potentials of unselected row and column electrodes are set to ``0''.
Then, high-frequency pulses A and b with a duty of 1× are supplied to the selected row and column electrodes. Therefore, the voltage applied to non-selected display elements becomes ``0'' at regular intervals, and the liquid crystal is kept in a non-responsive state.On the other hand, high-frequency pulses c or d are applied to the selected display elements, and the liquid crystal cumulatively responds. In Figure 7, the potentials of unselected row and column electrodes are set to 0 at regular intervals.
The selected row and column electrodes are supplied with high frequency voltages E and f with a duty of 1Z.

Therefore, the voltage applied to non-selected display elements becomes 0 at a constant period.
, and the liquid crystal remains in a non-responsive state. A high frequency pulse g or h is applied to the selected display element, and the liquid crystal responds cumulatively. FIGS. 8 and 9 show still other examples of voltage application. No. 8X19X2'.

1X7 shows the pulse applied to the row electrode X19X2'''''X7, and FIGS. 9y1 and 9y2 show the high frequency pulses applied to the unselected column electrode and the selected column electrode, respectively.

The non-selected electrode has a potential of 0 during the time T2 of one cycle. Figure 10A is Figure 8x3 and Figure 9y, respectively.
Figure 10B shows the voltage waveform applied to the display element to which the voltages shown in Figures 8x3 and 9y2 are supplied.

FIG. 11 shows the pulses supplied to the row and column electrodes,
The figure shows the voltage applied between each electrode due to this pulse. In FIG. 10A, an alternating current high frequency pulse P is applied once per period, and thereafter the applied voltage becomes ゛O゛ for a time T2, and the liquid crystal of this display element is held in a non-responsive state and no display is displayed.

That is, the pulse i of duty 1Z in FIG. 11 is supplied to the non-selected column once per cycle, the AC high frequency pulse p is applied between the electrodes, and then the applied voltage becomes ゛O゛ for a time T2. It becomes hidden. In Figure 10B, a constant unipolar high frequency voltage (pulses J, k, l in Figure 11)
is applied, the liquid crystal of this display element responds cumulatively, and displays.

In the above embodiment, the duty of the high frequency pulse is 1Z.
However, it is not limited to this, and may be arbitrarily selected depending on the frequency and the number of digits. Furthermore, the method of applying voltage to each display element is not limited to the method described above, and any method that produces the same operation as described above may be used.

Furthermore, the life of the liquid crystal can be extended by reversing the voltage applied to each display element every cycle or every period or more. Furthermore, in the above embodiment, the voltage ``0'' was supplied to the electrodes in the row direction at a constant cycle, and the display element was selected by the voltage applied to the electrodes in the column direction. The display elements may be selected by supplying the voltage at a constant cycle and applying the voltage to the electrodes in the row direction.

Furthermore, the display is not limited to matrix display, and may be used for segment display. As detailed above, according to the present invention, a unipolar high-frequency signal is applied to the liquid crystal display element to be selected so that it responds cumulatively, and a unipolar high-frequency pulse is applied to the unselected liquid crystal display element to cumulatively respond. Since a voltage of 0 or an AC high frequency pulse is applied before the display is activated to make the display non-responsive, a high-contrast display without crosstalk can be obtained with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a table showing a conventional voltage application method, FIG. 2 is an explanatory diagram showing drive electrodes and a drive circuit, and FIGS. 3, 4, and 5 are time charts showing signals applied to drive electrodes. Figures 6 and 7 are tables showing the voltage application method of other embodiments of the present invention, Figure 8910 is a time chart showing the signals applied to the drive electrodes, and Figure 11 is the voltage according to the signals in Figures 8 to 10. It is an explanatory diagram showing an application method. Xl

Claims (1)

[Claims] 1. In a liquid crystal display device consisting of a display element in which a liquid crystal is interposed between two electrodes, a timing signal is sequentially supplied to one electrode of each display element, and the other electrode of the selected display element is supplied with a timing signal similar to that of the one electrode. A signal is supplied such that a unipolar high-frequency pulse is constantly applied due to the potential difference between the two electrodes, thereby causing the liquid crystal to respond cumulatively. A signal is supplied so that a unipolar high frequency pulse is applied due to the potential difference between the timing signal and the timing signal. A method for driving a liquid crystal display device that responds.