DE19934124A1 - Manufacturing LCDs involves applying electric field during display cell filling process, nematic liquid crystal medium in display cell is homeotropically oriented when in rest state - Google Patents

Abstract

The method involves applying an electric field during the filling process with a field strength of 0.1 to 50 Volts per micron. A nematic liquid crystal medium that is used in the display cell is homeotropically oriented when in the rest state. The liquid crystal material is dielectrically negative. An Independent claim is also included for the use of a LCD, and for a LCD.

Description

Field of the invention

The present application relates to liquid crystal displays, in particular those with homeotropically oriented liquid crystal medium. It concerns further a method for producing such liquid crystal displays, especially of the ECB type. This procedure is used during the Filling the liquid crystal medium into the liquid crystal cell a field preferably an electric field applied. Optionally, that can Liquid crystal medium are additionally heated. Through this Measure or action will, compared to conventional Method that reduces filling time and the orientation of the Liquid crystal medium in the liquid crystal cell improved.

State of the art and task

In the production of liquid crystal displays is usually a Display cell assembled. This usually consists of two Substrates that are parallel to each other at a small distance, the ge desired layer thickness of the display corresponds to each other become. For this purpose, the peripheral edges of the two substrates glued together, but with a single or a number of several filling openings is left open. Are several openings provided, they are usually on one side of the cell. In some Cases, however, they can lie on different sides of the cell, where usually an arrangement on opposite sides is an advantage. Through this opening, or in the case of using multiple openings, through at least one of these openings, the liquid crystal medium in filled the cell. This can be done by capillarity. When filling By capillarity in the cell are preferably two or more openings provided, at least one of which as far as possible from the  other, especially those opposite, is arranged around the Allow exit of the gas in the cell.

However, this procedure is especially for displays with a larger area too time consuming. For this reason, it is common in mass production, to fill the liquid crystal displays in a vacuum filling system. there After lowering the pressure in the system, the empty cell will be in the Liquid crystal medium lowered and with the or the filling openings immersed. The cells have an or for this particular method several filling holes usually only on one side of the cell are arranged and all immersed in the liquid crystal medium. After immersing all filling holes in the liquid crystal medium the pressure in the filling station is increased. Usually up to about 1 bar.

However, it is also possible one or more openings on another Side, in particular at one of the above-mentioned openings opposite side to use, to the z. Legs Connecting device connected to the generation of negative pressure can be. In this case, the generation of negative pressure in the Filling system can be reduced or even completely avoided.

By filling the cells with the help of negative pressure becomes the speed of the filling process usually increased considerably.

A further increase in filling speed can in some cases be achieved by heating the liquid crystal material. For this becomes the container of liquid crystal and / or the whole filling station heated. The increased temperature reduces the viscosity of the Liquid medium.

However, this method is often set a narrow limit, as with rising temperature and the vapor pressure of the liquid crystal medium increases sharply and thus the volatility of the liquid crystal medium. This phenomenon is particularly disturbing, as the common ones Liquid crystal media mixtures of different types of Represent liquid crystal compounds that differ from the  Contribute vapor pressure over the medium whose volatility so in Dependence on their respective partial pressure over the mixture different. In particular, the liquid crystal compounds only two (typically six-membered) ring systems, such as. B. benzene rings or Cyclohexane rings, contained in the molecule, have relatively high vapor pressures compared to liquid crystal compounds the three or even four Ring systems included. This is especially true for the dielectric neutral connections.

Because of the different vapor pressures and thus different Volatilities of various individual compounds of the common ones Liquid crystal media is at reduced pressure and especially at increased temperature over time, including during the filling process, to observe a change in the composition. The less Volatile compounds, these are generally the more dielectric anisotropic compounds with two ring systems and the compounds, containing three or four ring systems accumulate in the mixture and there is an undesirable change in the properties of the liquid-crystal medium. The accumulation of the stronger dielectric anisotropic compounds usually leads to a reduction of Threshold voltage and in particular the accumulation of the three or four Ringsysteme containing compounds to increase the Clarification, although the increase in the threshold voltage in some Partial compensation can be made, but usually by one Increasing the viscosity and often reducing the Low-temperature stability of the nematic phase is accompanied.

For displays with vertical, so homeotropic edge orientation of the liquid crystal medium, such. For example, " e lectrically c ontrolled b irefringence" (ECB) displays are " c olor s uper h omeotropic" (CSH) displays or " v erally a ligned n ematic" (VAN) displays can, the filling time for displaying comparable goemetric dimensions is again significantly increased, compared to displays with planar, ie homogeneous surface orientation, such. TN and STN ads.

VAN displays are known inter alia from Koma, N. et al., International Display Workshop (IDW) '97 pp. 789-792 (1997), Kyehun, Kyeung Hyeon, et al. Asia Display 98 (18th IDRC) p. 383-386 (1998) and Tanaka, Y. et al., SID 99 Digest p. 206-209 (1999).

Such liquid crystal displays with homeotropic initial orientation may be those containing dielectric negative liquid crystal media use, such. B. the already mentioned above ECB displays (esp. CSH and VAN ads), as well as those that are dielectrically positive Use liquid crystal media, such as. B. Ads with an im Initial state homeotropically oriented, dielectrically positive Liquid crystal medium and to the liquid crystal layer substantially parallel field, z. B. with interdigital electrodes or with electrodes such they are used in IPS ads. This last embodiment with Dielectrally positive liquid crystal material is also called "inverse ECB" designated.

Especially for ads with homeotropic oriented Liquid crystal material, the filling time of the liquid crystal cells is too high, often for displays with a diagonal of 14 "even more than two Days.

Thus, especially for those ads with homeotropic Rando rientierung of the liquid crystal medium, but also for conventional Ads and in general for ads with homogeneous border orientation of the liquid crystal medium, the need to increase the filling speed increase.

the solution of the problem

In the investigations underlying the present application It has been found that the filling process by the application of a field, especially an electric field is significantly accelerated.

Alternatively, or in addition to an electric field can also ma be used. The field strength of the  magnetic field preferably 0.1 to 1 Tesla, with the smaller Field strengths are particularly preferred.

The application of an electric field to the cell during filling gangs can be done in different ways.

Thus, liquid crystal displays have electrodes with which the Liquid crystal display elements are controlled. Typical TN, STN and ECB ads have e.g. B. on each one of the two substrates either segment electrodes or pictorial electrodes with common or split counter electrodes or more or less matrix-shaped Row and column electrodes. Ads with so-called "interdigital Electrodes "such as IPS displays or VAN displays with dielectric positive liquid crystal media have electrodes on one of the substrates. These electrodes are used to drive the liquid crystal switching elements are intended and used in the present Application called pixel electrodes.

Depending on the type of display, the pixel electrodes can be controlled in different ways: "directly", by means of separate control lines, in "time division multiplexing", eg. By means of intersecting row and column lines or in "active" driving methods, by means of row and column lines, a matrix of each of the individual liquid crystal switching elements associated active electronic switching elements (eg., Diodes, thin film transistors) (TFTs of thin film transistors) and varistors. In particular, with the active matrix displays (AMDs of a ctive m atrix d isplays) these control lines are also referred to as bus lines. In this application, these drive lines are referred to as drive electrodes.

In addition to the already mentioned pixel electrodes and drive electrodes can with the different liquid crystal displays even more be provided electrically conductive structures. As typical examples are here so-called "masks" or "black masks", metallic Mirrors and external capacitors (eg storage capacitors) too call. These structures, the z. T. already in the known ads  are provided, as far as they are electrically conductive, in the present application referred to as auxiliary electrodes.

The pixel electrodes, the drive electrodes and the auxiliary electrodes of the Liquid crystal cell together in this application as Cell electrodes.

To accelerate the filling process of the liquid crystal cells z. B. to the cell electrodes, ie to the pixel electrodes, the Driving electrodes or the auxiliary electrodes of the liquid crystal cell, a corresponding voltage can be applied.

One possibility is the electrical voltage only to one of create three types of cell electrodes. But it can also be a Voltage to several or all of the different types of Cell electrodes are applied. It is also possible the electrical voltage to a combination of different types of To create cell electrodes, such. B. between a mirror layer or a mask and a BUS line.

The individual electrodes can be supplied with voltage at the same time be or in a chronological order, for. B. all BUS lines simultaneously or in succession.

All these methods of applying a voltage to the Cell electrodes have the advantage of no additional electrodes need. They are, however, depending on the display type and the used Cell electrodes limited in terms of usable voltages. Especially with active matrix displays, eg. B. driven at TFT Displays lead to high voltages at the pixel electrodes or especially at the gate bus and data bus lines regularly to defects in the active materials of the electrical switching elements.

Another disadvantage of using the cell electrodes is that the Orientation of the liquid crystal medium in this method only in Area of the electrodes to which the voltage is applied takes place. So will  z. B. when applying the voltage to the pixel electrodes the Liquid crystal medium only within the pixels and not in the Pixel interspaces oriented and thus only a part of the possible Acceleration of the filling process achieved.

In many cases, however, this method already brings the desired Be acceleration of the filling process. In addition, increasing the tempe Ratur and / or a magnetic field are used.

When using the cell electrodes to apply the voltage during the filling process can be made by selective selection of the used Cell electrodes are optimized to accelerate the filling process. In particular, the shape and orientation of the Cell electrodes are adapted to the filling process. So z. B. by Driving the pixel electrodes of VAN displays with dielectrically positive Liquid crystal materials with appropriate orientation of the Electric field in the flow direction or substantially in the flow direction the liquid crystal of the filling process are maximally accelerated. For this is optionally a corresponding arrangement of the filling openings advantageous. Furthermore, it is advantageous to design the cell electrodes in such a way that the largest possible proportion of the advertising space during filling is swept by the electric field.

An alternative method to speed up the filling process of Liquid crystal cells consist in the application of an electric field specially designed for this purpose electrode lines. These special electrodes are used in this application unlike the Cell electrodes called filling electrodes. These filling electrodes can become within the liquid crystal cell, in particular on the Liquid crystal medium facing sides of the substrates are, wherein the electrical requirements of the display code used must be taken into account. You can, however, also on the Outside of the substrates or other components of Liquid crystal cell or the liquid crystal display can be provided, as well as external to the liquid crystal cell and the liquid crystal display be executed independent electrodes.  

These fill electrodes may be on one side of the liquid crystal layer be appropriate or on both sides. The tension can vary, depending on Embodiment, both between the filling electrodes or between the Fill electrodes and the cell electrodes, wherein the drive electrodes and in particular the auxiliary electrodes are preferred to be applied.

An advantage of using filling electrodes, if necessary together with auxiliary electrodes and / or electrically uncritical Driving electrodes, the possibility of using is also higher Voltages compared to using the display electrodes and in particular the pixel electrodes. In addition, the course of the Füllelektroden the filling process and in particular to the flow direction of the Liquid crystal medium can be optimally adapted.

These filling electrodes, as mentioned above, both at the Inner sides and be provided on the outer sides of the cells. It is understood that provided on the insides of the cells electrodes opposite the bus and pixel electrodes as well as the active ones Switching elements (eg the TFTs) must be isolated.

On the outside of the cells provided filling electrodes can, however, they do not have to be transparent. As transparent electrodes can Among other advantageous ITO electrodes are used. When non-transparent electrodes may be metal films or Metal layers are used. These can be z. Aluminum, Silver, gold or other metals exist. Aluminum is due to its good reflection properties for visible light, due to its good manageability and, not least, also because of its relative low cost in general preferred. Silver and gold stand out on the other hand with comparable layer thicknesses by their better Conductivity and their higher corrosion resistance. Using correspondingly thin layers, gold films can also be transparent.

When using non-transparent filling electrodes for reflective displays, z. B. reflective TN displays, these can be on an outside of the Cells may be provided and optionally serve as a mirror layer, they  However, they can also be removed after the filling process. at transmissive and usually transflective Indications become non-transmissive filling electrodes after filling usually removed. An example, among others, for non-transparent Filling electrodes that can remain in the display are those already above mentioned, so-called black masks.

When using external filling electrodes, these can be different be executed. In the simplest case, they can have a plate shape than Line or wire electrodes or in various other Embodiments be formed.

During filling to the electrodes is preferred AC voltage. Preferred field strengths are 0.2 to 10 V / μm, particularly preferably 0.3 to 5 V / μm, very particularly preferably 0.5 to 2 V / μm and in particular about 1 V / μm.

If the voltage is applied to electrodes within the cell, are the preferred applied voltages in the order of their Preferred 1 to 50 V, 2 to 30, 10 to 25 V.

Preference is given to the inventive method for the preparation of Liquid crystal displays with homeotropic initial orientation applied and the liquid crystal displays according to the invention are prefers those with homeotropic initial orientation. For this Displays use dielectric in a preferred embodiment negative liquid-crystal media, such. For example, the ECB Ads (especially CSH and VAN ads). In another preferred embodiment use the inventive Display dielectrically positive liquid crystal media such. B. ads with in the initial state homeotropically oriented dielectrically positive Liquid crystal material and to the liquid crystal layer substantially parallel field, z. B. with interdigital electrodes. This last one Embodiment is also called "VAN" or "inverse ECB" display.  

The liquid-crystal displays according to the invention preferably contain nematic liquid-crystal media. Nematic liquid crystal media are Such liquid-crystal media used in the operation of the liquid crystal display, So at the operating temperatures of the liquid crystal display, in the nematic phase. The term "nematic phase" concludes here also the chiral nematic phase, also cholesteric phase called, one.

The used in the liquid crystal displays of the invention Liquid-crystal media are preferably nematic at 20 ° C and have nematic phases in a temperature range which is preferred at least 60 °, more preferably at least 90 °, especially preferably at least 100 °, and most preferably at least 120 ° is wide.

The temperature range of the nematic phase preferably extends at least from 0 ° C to at least 60 ° C, more preferably at least from -20 ° C to at least 70 ° C, most preferably at least from -30 ° C to at least 80 ° C and most preferred at least from -40 ° C to at least 80 ° C.

The operating temperature range of the liquid crystal displays is preferred from 30 ° C to 50 ° C (where the temperature is usually partially due to the Backlight over which the environment is raised), more preferably from 20 ° C to 60 ° C, most preferably from 10 ° C to 70 ° C, and most preferably from 0 ° C to 80 ° C.

Here, the preferred phase widths and Operating temperature ranges independently with the individual sub- and upper limits of the preferred temperature ranges, as well Each border independently be combined with each other, and further are the actual values for all specified ranges at least within the specified limits, the actual Values fall below the lower limits and the upper limits can exceed.  

In the method according to the invention are the liquid crystal media preferably in the liquid crystalline state, preferably in the nematic Phase filled in the liquid crystal cell.

Preference is given to using nematic liquid-crystal media. These are preferably either dielectrically negative and are preferred in used in conventional VA displays or they are dilektrisch positive and are preferred in VA displays with the liquid crystal layer used in parallel electric field.

The pressure in the filling system during filling is preferably in the range of 10 ^-3 to 10 ^-1 , preferably in the range of 5 × 10 ^-3 to 5 × 10 ^-2 , particularly preferably in the range of 7 × 10 ^-3 to 3 × 10 ^-2 , where all values, like all values for pressure in this application, are given in mBar.

The temperature of the liquid-crystal medium during filling in usually 10 ° C to 90 ° C, preferably 15 ° C to 70 ° C, more preferably 20 ° C to 60 ° C and most preferably 25 ° C to 50 ° C.

The filling times of the method according to the invention are for a display with a diagonal of 18 inches, preferably at a filling temperature of 50 ° C or less, preferably less than 50 hours (50 hours), especially preferably in the range of 2 hours to 45 hours, most preferably of 4 hours to 40 hours and more preferably in the range of 10 hours to 30 hours. At the However, most preferred are in the range of 12 hours to 24 hours.

The filling rates, preferably at a temperature of 50 ° C or less, are preferably greater than 10 ^-2 m / h, more preferably in the range of 1.5.10 ^-2 m / h to 0.25 m / h, most preferably of 1.2.10 ^-2 m / h to 0.13 m / h and particularly preferably in the range of 5.10 ^-2 m / h to 0.17 m / h.

The liquid-crystal displays according to the invention preferably have the following characteristics. The layer thickness of the liquid crystal layer is 2 microns to 6 microns, preferably 2.5 microns to 4 microns, especially  preferably 3 μm to 4.5 μm and very particularly preferably 3.7 μm to 4.3 μm. For the preferred VAN displays, the twist angle is ("Twist" angle) 0 °, the orientation layer used is a homeotropic, orienting, so the liquid crystal director perpendicular to Substrate surface oriented polyimide or polyamide and the Angle of attack ("tilt" angle) is in the range of 80 ° to 90 °, preferably in Range of 88 ° to 90 ° and more preferably in the range of 89 ° to 90 °. The liquid crystal displays according to the invention, or according to the According to the method of the invention produced liquid crystal displays have preferred diagonals in the range of 10 "to 60", especially preferably in the range of 12 "to 50", most preferably in the Range of 14 "to 40" and especially in the range of 14 "to 30". Where the information of the diagonal on the visible Screen diagonals and the liquid crystal cells depending on Design a more or less wide, not for display serving edge may have. This is usually about 0.5 "to 1.5 "wide.

The number of filling holes is one or more, preferably two or more and most preferably three or more.

The farthest distance from the filling hole or the filling holes within the Liquid crystal cell is usually 70% to 105% of the above indicated diagonal of the indications.

The electrode configuration of the displays may be the same as that of the However, it can also be specific to the in be adapted to the method described in the present application.

In the present application, the terms dielectrically mean positive Compounds such compounds with a Δε <1.5, dielectrically neutral compounds those with -1.5 ≦ Δε ≦ 1.5 and dielectrically negative Compounds with Δε <-1.5. Here, the dielectric aniso of the compounds determined by adding 10% of the compounds in one liquid crystalline host are dissolved and from this mixture the Kapa in at least one test cell of 10 μm density with homeo  troper and with homogeneous surface orientation at 1 kHz becomes. The measuring voltage is typically 0.5V to 1.0V, however always less than the capacitive threshold of the respective liquid crystal mixture.

As a host mixture, for dielectrically positive compounds ZLI-4792 and for dielectrically neutral as well as dielectrically negative connections ZLI-3086, both from Merck KGaA, Germany. From the Change in the dielectric constant of the host mixture after addition the compound to be tested and Extrapolartion to 100% of The compound used will be the values for each seeking compounds.

The term threshold voltage refers in the present Login to the optical threshold for 10% relative contrast (Vio) unless explicitly stated otherwise.

However, with respect to the liquid-crystal mixtures having negative dielectric anisotropy, the term threshold voltage is used for the capacitive threshold voltage (V ₀ , also called Freedericksz threshold: V _Fr ), unless explicitly stated otherwise.

All concentrations in this application, unless explicitly stated otherwise ver, are given in percent by weight and refer to the ent speaking total mixture. All physical properties are and have been determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status Nov. 1997, Merck KGaA, Germany, and are warranted for a temperature of 20 ° C, unless explicitly stated otherwise. Δn is determined at 589 nm and Δε at 1 kHz. The threshold voltages as well as the other electro-optical properties were determined in test cells manufactured by Merck KGaA, Germany, using white light with a commercial measuring instrument from Otsuka, Japan. For this purpose, in the case of dielectrically positive liquid crystal material, cells were used according to Δn of the liquid crystals having a thickness corresponding to the 1st transmission minimum according to Gooch and Tarry. The optical delay d.Δn of the cells was thus about 0.50 μm. The cells were operated in the so-called normal white mode (English "normally white mode") to the respective adjacent rubbing directions perpendicular passage direction of the polarizers. The characteristic stresses were all determined by vertical observation. The threshold voltage was given V ₁₀ for 10% relative contrast, the mid limit voltage V ₅₀ for 50% relative contrast and the saturation voltage V ₉₀ for 90% relative contrast.

In the case of the liquid-crystal media with negative dielectric anisotropy, the threshold voltage was determined as the capacitive swelling V ₀ (also called the Freedericksz threshold) in cells with leucithin homeotropically oriented liquids.

If necessary, the liquid-crystal media according to the invention can also be used further additives and chiral dopants in the usual amounts ent hold. The amount of these additives used is 0 in total to 10% based on the amount of the entire mixture, preferably 0.1 until 6%. The concentrations of the individual compounds used is preferably 0.1 to 3%. The concentration of these and similar Additives is used in the indication of the concentrations as well as the concentrations tion areas of the liquid crystal compounds in the liquid crystal media not included.

The compositions consist of several compounds before zugt from 3 to 30, particularly preferably from 6 to 20, in particular preferably 7 to 16 and most preferably from 10 to 14 Compounds that are mixed in a conventional manner. In the Usually, the desired amount is used in lesser quantity Components in the components constituting the main component dissolved, expediently at elevated temperature. Is the chosen one Temperature above the clearing point of the main constituent, so is the Complex It is particularly easy to observe the resolution of the solution process. It is however, also possible, the liquid crystal mixtures on other usual Because, for. B. using premixes or from a so-called "multi-bottle system" produce.  

By means of suitable additives, the liquid according to the invention crystal phases are modified so that they are known in each type of TN-AMD or ECB, in particular VAN-AMD can be used.

The following examples serve to illustrate the inventions without restricting it. In the examples, the melting point T (C, N), the transition from the smectic (S) to the nematic (N) Phase T (S, N) and clearing point T (N, I) of a liquid crystal substance in degrees Celsius indicated. The percentages are by weight.

Unless otherwise indicated, all pros are above and below Numbers are percent by weight and the physical properties are the values at 20 ° C, unless explicitly stated otherwise.

All values given for temperatures in this application are ° C and all temperature differences according to the degree of difference, if not explicitly stated otherwise.  

In the present application and in the following examples, the structures of the liquid crystal compounds are indicated by acronyms, wherein the transformation into chemical formulas according to the following Tabel len A and B takes place. All radicals C _n H _{2n + 1} and C _m H _{2m + 1} are straight-chain alkyl radicals with n or m C atoms. The coding according to Table B is self-evident. In Table A, only the acronym for the basic body is given. In the individual case, a code for the substituents R ¹ , R ² , L ² and L ² follows separately from the acronym for the main body with a dash:

Table A

Table B

The liquid crystal mixtures preferably used according to the present invention preferably contain:

• - five or more compounds selected from the group of the Tables A and B indicated compounds and / or
• Two or more compounds selected from the group of Table A and / or
• Four or more compounds selected from the group of Table B given compounds.

The following examples are intended to illustrate the invention without limiting it. Above and below mean percentages by weight. All temperatures are in degrees Celsius. Δn means optical anisotropy (589 nm, 20 ° C), Δε the dielectric anisotropy (1 kHz, 20 ° C), HR the voltage holding ratio (at 100 ° C, after 5 minutes in the oven, 1 V), V ₁₀ , V ₅₀ and V _90, the threshold voltage, Mittgrauspension or saturation voltage were determined at 20 ° C.

Examples example 1

A liquid crystal medium having the following properties

Clearing point (T (N, I)) 73.0 ° C T (S, N) <-40 ° C Δn (589 nm, 20 ° C) .0830 Δε (1 kHz, 20 ° C) -5.1 K ₁₁ (20 ° C) 13.2 K ₂₂ (20 ° C) n. b. K ₃₃ (20 ° C) 14.0 V ₀ (20 ° C) 1.76 V ν ₂₀ (20 ° C) n. b. γ ₁ (20 ° C) 184 mPa.s

and the composition

connection Concentration / mass% CC-5-V 13.0 PCH-304FF 20.0 PCH-504FF 20.0 CCP 202ff 8.0 CCP 302FF 11.0 CCP 502FF 8.0 CCP 21FF 10.0 CCP 31ff 10.0 Σ           100.0         

was filled into different types of test cells. In each case with or filled without electric field. The test cells came from the Test cell production of Merch KGaA. The substrates were borosilicate glass, the electrodes of indium tin oxide had a sheet resistance of  10 Ω / (ohms per square inch). As an orientation layer was. lecithin the Merck KgaA used.

The filling was done by capillarity. The pressure was 1015 mbar, the Temperature 22 ° C.

The structure and dimension of the two related cell types, as well as their respective electrode layout are shown in Fig. 1. The layer thickness of the cells of type 1 is 20 microns, the type 2 is 30 microns.

As shown in Fig. 1, Type 1 cells have electrodes that extend over almost the entire area of the cells. In contrast, Type 2 cells have electrodes that cover only a portion of the cell area, similar to matrix displays such as those shown in Figs. B. AMD or STN multiplex displays is the case.

The results of the various filling experiments are given in Table 1 compiled.

The results of filling the cells of type 1 clearly show the Reducing the filling time by applying a voltage of 20 V to 580 s, compared to the filling time of 630 s without applied voltage, ie a reduction of almost 10%.

As expected, the filling process for cell type 2 is in the range of Füllstrecke B, in which no electrodes are present, by applying a Voltage also not affected. It is different in the area of the route C in which are located in a part of the cell cross section electrodes. Here For example, a significant shortening of the fill time from 738 s to 648 s will occur about 12% observed.

This reduction in filling time for the route C in the cells of the type 2 by 12% is about 50% larger than that of cell type 1 watching. Surprisingly, this ratio is just right the ratio of the field strengths used (the type 2 cells are correspondingly thinner than that of type 1). This result is  Surprisingly, because in cells of type 2, the electrodes are not over extend the entire area C of the cells, while the electrodes of the Cover cells of type 1 the whole area A.

Table 1

Fill times at different field strengths

Claims (10)

1. A method for producing a liquid crystal display cell, characterized in that a field is applied during the filling process. 2. Method nor claim 1, characterized in that the field laid is an electric field. 3. The method according to at least one of claims 1 and 2, characterized characterized in that the liquid crystal medium is a nematic liquid crystal medium. 4. The method according to at least one of claims 1 to 3, characterized characterized in that the liquid crystal medium in the display cell is homeotropically oriented at rest. 5. The method according to at least one of claims 1 to 4, that the Liquid crystal material is dielectrically negative. 6. The method according to at least one of claims 1 to 5, characterized characterized in that it is in the liquid crystal display cell is a VAN display cell. 7. The method according to at least one of claims 1 to 6, characterized characterized in that the field strength of the applied electric Field is 0.1 to 50 V / μm. 8. A liquid crystal display cell prepared by a method according to at least one of claims 1 to 8. 9. Use of a liquid crystal display cell according to claim 8 in egg ner liquid crystal display. 10. A liquid crystal display containing one or more liquid crystal Display cells according to claim 8.