JPS59187323A - Driving method of liquid crystal display element - Google Patents

Abstract

PURPOSE:To reduce the voltage applied to heat electrodes by preheating liquid crystal on the heat electrodes whose temperature is raised above initial temperature. CONSTITUTION:Switching elements S11, S21, S31, and S41 are switches for applying the voltage V1 of a heating power source 35 to heat electrodes 31, 32, 33, and 34, and switching elements S12, S22, S32, and S42 are switches for applying the voltage V2 of a preheating power source 36. When a heat electrode is heated, the switching element S12 is turned on firstly to apply the preheating voltage V2. At this time, the liquid crystal on the heat electrodes rise in temperature up to temperature T1. Then, the switching element S12 is turned off and the switching element S11 is turned on to apply the heating voltage V1, so that the temperature of the liquid crystal rises up to T2. This driving method allows driving by the preheating voltage V2 and heating voltage V1 which are lower than conventionl heating voltages.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a display device using a liquid crystal, and more particularly to a liquid crystal display device that utilizes thermo-electro-optic effects of slimy liquid crystals and the like.

[Prior art]

Thermal/electrical-optical effects of liquid crystals? The display device used is U.S. Patent No. 3,796,999 or U.S. Patent No. 3,836,2.
These devices, which are described in detail in No. 43, irradiate a cell filled with a liquid crystal material (for example, Smetachine liquid crystal) with a laser beam to locally heat any part of the cell, causing a phase transition of the liquid crystal material. The process includes a process of raising the temperature above the temperature, and a process of controlling the entire optical material of the i-layer after cooling by applying or not applying an electric field in the subsequent cooling process, thereby achieving a complete display.

Furthermore, M. Hareng et al.
rectView, Matrix @Address
ed Smect ic A, L, C.

D. Panel, 1982 International
alRe5earchConference (19
82) published a display device based on almost the same principle as above, but they used Joule heat, which is generated by passing electricity through a heat electrode provided on the substrate of a liquid crystal cell, as a heat source. We are using.

According to the paper by M. Hareng et al., the smetatenodic liquid crystal in its initial state has a homeotropic pink orientation as shown in Figure 1, which can be seen in terms of its transparency.

In this state, the liquid crystal component is heated by the heat generated when electricity is applied to the heat rod, making it an isotropic liquid. After that, when the power is turned off, the nematic phase returns again? At this point, the scattering state (
The simmering state or transparent state (initial state) is determined.

In order to achieve this operation, an element configuration as shown in FIG. 2 and a method of applying one pressure are known.゛The cross-sectional structure of the liquid crystal element is as shown in Fig. 2(a), in which a transparent electrode 23 provided on a transparent base plate 21 faces a transparent liquid crystal layer 25 of an appropriate thickness. It consists of a heat electrode provided on the substrate 22.

Transparent Ward @! 23 and the heat source 24 are arranged in an X-Y matrix as shown in FIG. 2 (C).
As shown in , the temperature of the liquid crystal 25 on the 1' electrode is raised by applying a voltage in time series to the 0'(lj) electrode.At this time, the temperature of the liquid crystal 25 on the Table 71 is achieved according to the above-mentioned principle by increasing the temperature in the temperature range where the isotropic liquid phase decreases (T).

Unfortunately, during the cooling process, the electric field applied to the VC is applied to the transparent electrode 23.
It is done by

The disadvantage of this prior art is that heat 1 has a high 'iiV pressure applied to the poles. For example, M, 11-4a
Another paper by Renshi”A F l;]t 5rnec
tic JJ igui dCrystal ]J
isplay” S I D 8 2 DI
CnoESi” PP.

252-253 (1982J VCl, 6t, 25V
(1)-% pressure was required.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a driving method capable of reducing the applied pressure of a heat electrode.

[Summary of the invention] The present invention is characterized in that the liquid crystal on the heat electrode to be heated is preheated to a temperature higher than the initial temperature, and the temperature is raised to an isotropic liquid phase using a relatively low heating pulse voltage. cormorant [Embodiments of the invention]

VC for detailed explanation of the present invention, Figures 3 and 4.
There are kumquats. In Fig. 3, the heat electrode 31°32.33
．． 34 and the switching element S+ connected to this
What is the connection status between +~842, heat power supply 35, and preheating power supply 36? show. Here, the switching element SLI + S
21 + S31 + S41 ke Heat power supply 35 voltage■,? It operates as a switch for applying heat to the electrode, and the switching element S,2゜822, S3□,S
42 operates as a switch that applies voltage 2 of the preheating power source 36.

Heating of the heat' electrode is carried out in time series as in the conventional example, but in the present invention, as shown in FIGS. 4(a) and 4(b), the pre-pA voltage is ■2
Apply. That is, to explain the driving method for all examples of the heat electrodes 31 in FIG. 3, first, as shown in FIG. 4(a), the switching element 81 is turned on and a preheating voltage 2 is applied. At this time, the liquid crystal above the heat
As shown in Figure (C), the temperature is raised to temperature TI. after that,
When the switching elements s and 2i are turned off and the switching elements 8++ and 2i are turned on to apply a heat voltage of 1 and 1, the temperature of the liquid crystal rises at T2.

At this time, the preheating temperature is the initial temperature T. must be lower than the temperature TNr at which it transitions to the isotropic liquid phase. Furthermore, the temperature T raised by the heat voltage is 18
Must be 1 or more.

According to such a driving method, it is possible to drive with a preheating voltage (2) and a heating voltage (v, iq) lower than that on the heating electrode described in the conventional example.

The inventors' experience was to use a mixture of cyanobiphenyl liquid crystals (manufactured by S-IBDH) as the smectisota liquid crystal.
The thickness of the liquid crystal layer was set to 15 μrn, and the heating electrode was made of an aluminum vapor-deposited film.The conventional method required a heating voltage of 40V, but this method'''
Is C the heat voltage? It has become clear that it can be reduced at 25V to 30V'E.

Furthermore, when carrying out the entire invention, it is also effective to apply a preheating voltage to the heat electrode whose temperature is to be raised next during the period when the heat voltage is being applied to any heat electrode. FIG. 5 shows the voltage waveform applied to the heat electrode and the temporal change in temperature in this case.

〔Effect of the invention〕

According to the present invention, since the time required for preheating temporally overlaps with the heat voltage application time in the previous stage, the time required for preheating can be substantially shortened.

[Brief explanation of the drawing]

Figure 1 shows the thermal/electrical optical effects of smectinta liquid crystal.
FIG. 2 is an explanatory diagram of a conventional example, FIG. 3 is a plotter diagram of an embodiment of the present invention, and FIGS. 4 and 5 are waveform diagrams of FIG. 3. S + + + S211 S 31 , S 4 H
...Sinching element, s'+2, 822.832
184□...Swiss tink element, 31.32,33.
34...Heat electrode, 35...Heat river power supply, 36
...Power supply for preheating. Agent Patent Attorney Akio Takahashi Figure 1 (cL) ri3 $3 Trouble I $4 Figure 52 珈″■--i＼4

Claims (1)

[Claims] 1. A liquid crystal layer, means for changing the temperature of the liquid crystal, and an electric field?
In a method of driving a liquid crystal display device, the method includes a means for applying a heat voltage and a voltage pulse, before applying a heat voltage pulse that raises the temperature of the liquid crystal to an isotropic liquid phase, to a temperature lower than the temperature at which the liquid crystal reaches the isotropic liquid phase. A driving force method for liquid crystal display elements characterized by applying a full preheating voltage pulse to raise the temperature. 2. In claim 1, the preheating pressure pulse is applied at the same time as the heat pressure pulse, and the preheating voltage pulse application port is applied after the heat voltage pulse is applied. A method for driving a liquid crystal display element, characterized in that: