RU1830545C - Control process of ferroelectric liquid crystal panel - Google Patents

Abstract

Usage: the invention relates to automation and computer engineering and can be used in controlling liquid crystal devices. SUMMARY OF THE INVENTION: the method is characterized in that the switching pulse, which is formed on the LCD matrix element as the difference between the information and gate pulses, consists of three fragments, the middle of which has a duration equal to the sum of two other fragments, which serve to compensate for the constant component that is. 5 ill.

Description

The invention relates to electronic equipment, and more particularly to the management of liquid crystal devices, in particular to the control of matrix ferroelectric liquid crystal devices having bistability.

An object of the present invention is to increase the information rate of a ferroelectric liquid crystal device while reducing power consumption by reducing repolarization cycles and eliminating flicker.

In FIG. 1 shows the dependence of the switching time on the amplitude of the switching pulse for switching pulses of various shapes; NC FIG. 2 is a timing chart of control pulses in accordance with the invention, Example 1; in FIG. 3 is a timing chart of control pulses in accordance with the invention, Example 2; in FIG. 4 is a timing chart of control pulses in accordance with the invention, Example 3; Fig. 5 is a timing chart of control pulses in accordance with the invention, Example 4, control of pulses of the same polarity.

In FIG. 1: 1 - switching time when controlling single pulses; 2 - switching time for voltage control in the form of a meander; T is the switching time; U is the amplitude of the switching pulse.

In Figs. 2-5: (along the abscissa axis — time, along the ordinate axis — voltage), 3 — gating pulses in the first and second half frames; 4 - information pulses when recording 1; 5 - information pulses when writing 0; 6 is a timing diagram of a voltage on a gated row element during recording 1; 7 is a timing diagram of a voltage on a gated string element when writing 0; 8 - duration (recording time) of the line; 9-duration of the first half frame.

Matrix addressing scheme of a ferroelectric liquid crystal device

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The equipment must satisfy the following requirements: the voltage pulse applied to the element of the gated line must contain a fragment whose amplitude product is equal to or higher than the switching threshold in the required direction and the remaining fragments are possible to reduce the recording time of the line and thereby to increase the performance of the device. The elements of the remaining rows should not change their state, i.e. a voltage pulse must be applied to them at any time, the product of the amplitude and the duration of which is significantly lower than the switching threshold. At the same time, for any element over a certain period of time, the constant component of the applied voltage must be compensated, regardless4 of the content of the input information.

The prototype uses a prepulse of opposite polarity in the gated signal to compensate for the DC component, which leads to the disadvantages of the addressing scheme described above. In the present invention, the compensating part of the pulse applied to the element of the gated string is divided into two fragments, with one compensating fragment of the opposite polarity preceding the switching fragment, the second fragment of the opposite polarity following the switching one. Moreover, the total duration of fragments of opposite polarity does not exceed the duration of the switching fragment, and their amplitude is one and a half times less, the quality indicator is three. As can be seen from Figures 2-5, full compensation of the constant component occurs in this case in two half frames. A decrease in the amplitude of the compensating parts by more than one and a half times with respect to the amplitude of the switching part will lead to an increase in the voltage amplitude on the elements of the gated string, the state of which does not need to be changed, and will reduce the quality index of the addressing circuit.

The presence in the switching pulse applied to the element of the device, only one fragment having the product of the amplitude by the duration equal to or higher than the switching threshold, leads to lower power consumption and increased addressing speed compared to the prototype by reducing the pulse duration required to switch at the same amplitude electric floor. On the

FIG. Figure 1 shows the dependence of the switching time on the pulse amplitude for pulses of various shapes. The addressing mode proposed in the prototype corresponds to switching pulses in the form of a meander, i.e. first switching in the opposite direction, and then in the desired. The addressing method in accordance with the invention corresponds to

switching by single pulses, which allows reducing the pulse duration and, therefore, increasing the addressing speed by no less than one and a half times. Examples of the specific shape of the control line and column pulses shown in Figures 2 and 3 do not need to be understood. Figure 4 shows the shape of the control pulses in which, in the first half frame, 1 is recorded on odd lines, 0 on even lines, and on the second, vice versa. The advantage of such a scheme is the elimination of the addition of pulses of one polarity at the end of the length of the previous line and the beginning of the next and, as a consequence, an increase in the quality index in some cases.

To obtain a recording speed of information close to television, i.e. line recording time of the order of 60 μs

The switching pulse should have an amplitude of about 20 V. At the same time, the control microcircuits should ensure the formation of pulses with an amplitude of + 20V and -20V. The modification of the matrix control circuit shown in Fig. 5 provides the generation of pulses of the required configuration on the device elements when applying only one polarity to the rows and columns of pulses, i.e. halves control chip requirements.

The use of the proposed matrix control scheme for a megetoelectric liquid crystal device will make it possible to increase the speed of the device (reduce the recording time of a string by 25-30%) by more than halving the power consumption and eliminating flicker.

Claims (1)

SUMMARY OF THE INVENTION A method for controlling a matrix ferroelectric liquid crystal panel, comprising simultaneously supplying to the horizontal and vertical busbars of the panel sequences of strobe and information signals in the form of a set of different-polarity pulses, characterized in that that, in order to increase the speed and quality of the display by eliminating flicker and reducing power consumption, a set of different-polarity pulses is formed of three different-polarity pulses relative to each other, the average duration of which is equal to the sum of the extreme durations, the pulse amplitudes of the information signal are equal, and the amplitude average1, ms The g of the strobe signal pulse exceeds the extreme amplitudes so that the sum of the amplitudes of the average strobe and information signal pulses is greater than or equal to the switching threshold voltage. 0.5 Q4 0.3 Q2 0.1 twenty f№ tf-b y bHJ --- LTLrLn: i i i i  aJUTL-jrUTUU; I tffl u-u LJ nirv, i i No-jtl $ jt. 2 thirty U, & FIG. / -jtf I I 4& - gZTs M --- Ftf -Fig. 3 w I I & II Ii ifRfeftf-JinfUlTL TJtnJL -TILP; -fbfl -J1 LJ ruin U, i ,,,. 1 n Inji-iil Ina l. 8., I II (rig 4 i i .--- jil Wui