CN103424933A

CN103424933A - Liquid crystal element and liquid crystal display

Info

Publication number: CN103424933A
Application number: CN2013101785423A
Authority: CN
Inventors: 加藤惠介; 都甲康夫
Original assignee: Stanley Electric Co Ltd
Current assignee: Stanley Electric Co Ltd
Priority date: 2012-05-18
Filing date: 2013-05-15
Publication date: 2013-12-04
Anticipated expiration: 2033-05-15
Also published as: JP5992203B2; CN103424933B; KR20130129120A; JP2013242379A; KR102036620B1

Abstract

The present invention relates to a liquid crystal element and a liquid crystal display, which can be improved in the memory nature under the hot environments of the liquid crystal display using the liquid crystal element and this using transition between two oriented states. The liquid crystal element includes a 1st substrate and a 2nd substrate which orientation treatment is performed to each whole surface, and were arranged oppositely; a liquid crystal layer provided between the whole surface of said 1st substrate, and the whole surface of said 2nd substrate; two or more columnar spacers provided between the whole surface of said 1st substrate, and the whole surface of said 2nd substrate. A pre tilt angle which said 1st substrate and said 2nd substrate are set up in the direction of the aforementioned orientation treatment so that a liquid crystal element of the aforementioned liquid crystal layer may produce the 1st oriented state twisted in the 1st direction, and each gives to a liquid crystal element of the liquid crystal layer concerned in an interface with the aforementioned liquid crystal layer is not less than 20 degrees. The aforementioned liquid crystal layer contains a chiral material of a property to produce the 2nd oriented state to which the aforementioned liquid crystal element was twisted in the 2nd direction contrary to said 1st direction.

Description

Liquid crystal cell, liquid crystal indicator

Technical field

The present invention relates to the improvement technology of the electro-optical characteristic in liquid crystal cell and liquid crystal indicator.

Background technology

Disclose the liquid crystal display cells (oppositely TN type liquid crystal cell) of the novelty of having utilized the transformation between two kinds of state of orientation in TOHKEMY 2011-203547 communique (patent documentation 1).The liquid crystal display cells of this conventional example has the 1st substrate and the 2nd substrate that has carried out orientation process and is configured in the liquid crystal layer that carries out twisted-oriented between them, includes chiral material in liquid crystal layer.And, when while in establishing liquid crystal layer, not containing chiral material, the sense of rotation of liquid crystal molecule distortion is the 1st sense of rotation, chiral material applies the rotatory towards 2nd sense of rotation contrary with the 1st sense of rotation to liquid crystal molecule.In addition, the 1st substrate and the 2nd substrate have carried out orientation process in the mode that produces respectively the tilt angle below 45 ° more than 20 °.Be provided with electrode on the 1st substrate and the 2nd substrate, described electrode can produce respectively electric field on the bed thickness direction of liquid crystal layer and perpendicular direction.According to this structure, can realize thering is the Memorability that can maintain show state, and obtain the liquid crystal display cells of the display quality excellence of high-contrast.

For example, but, in the liquid crystal display cells of above-mentioned conventional example, although Memorability at room temperature is high, when peripheral temperature uprises (more than 60 ℃), Memorability reduces sometimes, a part can't keep show state.Therefore, such as the variation in peripheral temperature such as vehicle-mounted purposes, aircraft purposes, outdoor applications, under large service condition, Memorability is insufficient.In addition, in the liquid crystal display cells of conventional example, due to the disclination line produced between the clearance material interspersing among between substrate, sometimes cause the transmissivity in the zone of the bent distortion of exhibition (splay twist) orientation of distortion on above-mentioned the 2nd sense of rotation to reduce, have in this respect room for improvement.And, the shape of disclination line has been reflected in boundary line between the zone of reverse twist (reverse twist) orientation of distortion on above-mentioned the 1st sense of rotation and the zone of the bent twisted-oriented of exhibition, thereby sometimes, boundary line becomes concavo-convex, cause display quality to reduce, also have in this respect room for improvement.

[patent documentation 1] TOHKEMY 2011-203547 communique

Summary of the invention

One of purpose of concrete mode of the present invention is, provides and can improve the liquid crystal cell that has utilized the transformation between two kinds of state of orientation and the technology of having used the Memorability of liquid crystal indicator under hot environment of this liquid crystal cell.

One of purpose of concrete mode of the present invention is, the technology that can prevent due to the reduction of the liquid crystal cell that has utilized the transformation between two kinds of state of orientation and the display quality that used the disclination line in the liquid crystal indicator of this liquid crystal cell to cause is provided.

The liquid crystal cell of a mode of the present invention comprises: the 1st substrate and the 2nd substrate that (a) relatively configure, and the 1st substrate and the 2nd substrate one side separately have been implemented orientation process, (b) liquid crystal layer, it is arranged between the one side of the one side of the 1st substrate and the 2nd substrate, and (c) a plurality of column spacers, it is arranged between the one side of the one side of the 1st substrate and the 2nd substrate, (d) direction of the orientation process of the 1st substrate and the 2nd substrate is set to, produce the 1st state of orientation of liquid crystal molecule distortion on the 1st direction of liquid crystal layer, and, described the 1st substrate and the 2nd substrate are more than 20 ° at the tilt angle that is given to the liquid crystal molecule of this liquid crystal layer with the interface of liquid crystal layer respectively, (e) liquid crystal layer contains chiral material, this chiral material has following character: the 2nd state of orientation that produces liquid crystal molecule distortion on the 2nd direction with the 1st opposite direction.

In above-mentioned liquid crystal cell, be configured to the gap that keeps the 1st substrate and the 2nd substrate with a plurality of column spacers, make thus the same the playing a role of columnar interval image dividing wall of the zone that is configured in the 1st state of orientation and the boundary vicinity in the zone of the 2nd state of orientation, can produce two kinds of discontinuous states of state of orientation.Thus, can block the transformation of state of orientation two-wayly, can improve Memorability, therefore, even under the condition of high temperature, also can stably keep each state of orientation.Therefore, can also be applied to the purposes that vehicle-mounted purposes, aircraft purposes, outdoor applications etc. require high reliability.In addition, and spherical sept is compared as the situation of clearance material, eliminated the disclination line between clearance material, the reduction of the display quality that therefore can avoid the shape by the disclination line to cause.And the weak scattering caused because of the disclination line disappears, therefore the transmissivity in the zone of the 2nd state of orientation (opening up bent twisted state) increases, and the contrast on each of the 1st state of orientation and the 2nd state of orientation is interregional improves.

In above-mentioned liquid crystal cell, a plurality of column spacers for example have respectively the profile of wire or point-like when overlooking.

Above-mentioned liquid crystal cell also comprises voltage applying unit, this voltage applying unit applies voltage in order to produce electric field to described liquid crystal layer, produce electric field by described voltage applying unit on the direction substantially vertical with described the 1st substrate and described the 2nd substrate one side separately, make thus described liquid crystal layer change to described the 1st state of orientation, by on the direction with described the 1st substrate and described the 2nd a substrate almost parallel separately, producing electric field, make thus described liquid crystal layer change to described the 2nd state of orientation.

The liquid crystal indicator of a mode of the present invention has a plurality of pixel section, and the plurality of pixel portion is not used the liquid crystal cell of the invention described above and formed.

According to said structure, can access liquid crystal indicator as described below: the bistability (Memorability) of two kinds of state of orientation by utilizing liquid crystal cell, thereby basically do not need electric power while rewriting except showing, and at high temperature also can not reduce Memorability, display quality is also very excellent.

The accompanying drawing explanation

Fig. 1 is the schematic diagram that the action of reverse TN type liquid crystal cell schematically is shown.

Fig. 2 is the concept map of the relation of the state of orientation of the liquid crystal layer while changing from the reverse twist state to the bent twisted state of exhibition for explanation and direction of an electric field.

Fig. 3 is the cut-open view that the structure example of reverse TN type liquid crystal cell is shown.

Fig. 4 is the schematic diagram of shape when the overlooking of column spacer is shown.

Fig. 5 is the schematic cross sectional views that the electric field that uses each electrode pair liquid crystal layer to apply is described.

Fig. 6 is the figure that the structure example of liquid crystal indicator schematically is shown.

Fig. 7 is the figure of microscopic examination picture that the liquid crystal cell of embodiment 1 is shown.

Fig. 8 is the figure of microscopic examination picture that the liquid crystal cell of embodiment 2 is shown.

Label declaration

1: the upside substrate

2: the downside substrate

3: liquid crystal layer

51: the 1 substrates

52: the 1 electrodes

53,57: alignment films

54: the 2 substrates

55: the 2 electrodes

56: dielectric film

58: the 3 electrodes

59: the 4 electrodes

60: liquid crystal layer

61: column spacer

71,72,73: driver

74: pixel section

A1～An, B1～Bm, C1～Cn, D1～Dn: control line

Embodiment

Below, with reference to accompanying drawing, embodiments of the present invention are described.

Fig. 1 roughly illustrates reverse TN(RTN) schematic diagram of the action of type liquid crystal cell.As the basic structure of reverse TN type liquid crystal cell, there is upside substrate 1 and the downside substrate 2 of relative configuration and be arranged on the liquid crystal layer 3 between them.Upside substrate 1 and downside substrate 2 surface have separately been implemented to the orientation process such as friction treatment.Upside substrate 1 and downside substrate 2 according to their orientation process direction (meaning with arrow in figure) in the cross one another mode of the angle of 90 ° of front and back, relatively configuration.Liquid crystal layer 3 forms by upwards between side group plate 1 and downside substrate 2, injecting nematic liquid crystalline material.Used the liquid crystal material that is added with chiral material in this liquid crystal layer 3, this chiral material produces following effect: make liquid crystal molecule upper distortion of specific direction (being the right rotation direction in the example of Fig. 1) in its azimuth direction.About so reverse TN type liquid crystal cell, by the effect of chiral material, under original state, liquid crystal layer 3 becomes and is carrying out the bent twisted state of exhibition that carries out distortion in the Zhan Qu orientation.When the liquid crystal layer 3 of opening up bent twisted state for this, while applying the voltage over saturation voltage on its bed thickness direction, liquid crystal molecule is transferred to the reverse twist state (evenly twisted state) of distortion on the anticlockwise direction.In the liquid crystal layer 3 of such reverse twist state, the liquid crystal molecule in main body (bulk) tilts, and therefore shows the effect of the driving voltage that reduces liquid crystal cell.

Fig. 2 is the concept map of the relation of the state of orientation of the liquid crystal layer while changing from the reverse twist state to the bent twisted state of exhibition for explanation and direction of an electric field.As shown in Fig. 2 (A), for the electric field in horizontal direction (Electric field) with respect to real estate, by the direction setting that applies of electric field, be, make it as far as possible not parallel with the long axis direction of the liquid crystal molecule (being the liquid crystal molecule with grain pattern in figure) of the substantial middle of the bed thickness direction of liquid crystal layer under the reverse twist state, but become vertical or subvertical state.Thus, the liquid crystal molecule of the substantial middle of the bed thickness direction of liquid crystal layer re-starts orientation along direction of an electric field, so, as shown in Fig. 2 (B), the state of orientation of liquid crystal layer is from the reverse twist state-transition to opening up bent twisted state.In addition, when the liquid crystal layer for the reverse twist state, parallel or when connecing subparallel state and having applied electric field with the long axis direction of the liquid crystal molecule of the substantial middle with its bed thickness direction, be difficult to produce the transformation from the reverse twist state to the bent twisted state of exhibition.This is because the substantial middle in the bed thickness direction of liquid crystal layer, can produce because of electric field the reorientation of liquid crystal molecule hardly.According to above situation, in order oppositely to change freely between two kinds of state of orientation in TN type liquid crystal cell, the electric field (transverse electric field) of the electric field (longitudinal electric field) that the needs generation is corresponding with the bed thickness direction of liquid crystal layer and perpendicular direction, and, for transverse electric field, need to become substantially vertical with the long axis direction of the liquid crystal molecule of the substantial middle of the bed thickness direction of the liquid crystal layer of reverse twist state or close to vertical direction.About for applying freely the element structure of these longitudinal electric fields and transverse electric field, below enumerate object lesson and describe.

Fig. 3 is the cut-open view that the structure example of reverse TN type liquid crystal cell is shown.Liquid crystal cell shown in Fig. 3 has the basic structure that accompanies liquid crystal layer 60 between the 1st substrate (upside substrate) 51 and the 2nd substrate (downside substrate) 54.Below, in further detail the structure of liquid crystal cell described.In addition, about the parts such as encapsulant to being sealed around liquid crystal layer 60, omit diagram and explanation.

The 1st substrate 51 and the 2nd substrate 54 are respectively transparency carriers such as glass substrate, plastic base.As shown in the figure, the mode that the 1st substrate 51 is relative with one side each other with the 2nd substrate 54, be provided with specified gap (for example a few μ m) and fit.In addition, although omitted special diagram, can on any one substrate, form the switching devices such as thin film transistor (TFT).

The 1st electrode 52 is arranged on the one side side of the 1st substrate 51.In addition, the 2nd electrode 55 is arranged on the one side side of the 2nd substrate 54.The 1st electrode 52 and the 2nd electrode 55 are respectively by forming such as nesa coatings such as tin indium oxides (ITO), carrying out composition.

Dielectric film (insulation course) 56 is arranged on the 2nd substrate 54 in the mode that covers the 2nd electrode 55.This dielectric film 56 for example, such as being silicon oxide film, silicon nitride film, silicon oxynitride film or their inorganic insulating membrane or the organic insulating films (acrylic compounds organic insulating film) such as stacked film.

The 3rd electrode the 58, the 4th electrode 59 is separately positioned on the above-mentioned dielectric film 56 on the 2nd substrate 54.The 3rd electrode 58 in present embodiment and the 4th electrode 59 are respectively to have a comb-like electrode that a plurality of electrodes prop up, and prop up the mode of alternately arranging with electrode each other and are configured (with reference to Fig. 4 described later).The 3rd electrode 58 and the 4th electrode 59 are respectively by forming such as nesa coatings such as tin indium oxides (ITO), carrying out composition.About the 3rd electrode the 58, the 4th electrode 59 electrode separately, prop up, for example width is 20 μ m, and electrode gap is set as to 20 μ m and is configured.

Alignment films 53 is arranged on the one side side of the 1st substrate 51 in the mode that covers the 1st electrode 52.In addition, alignment films 57 is arranged on the one side side of the 2nd substrate 54 in the mode that covers the 3rd electrode 58 and the 4th electrode 59.Each

alignment films

53,57 has been implemented to the orientation process (for example friction treatment) of regulation.

Liquid crystal layer 60 is arranged on the 1st substrate 51 and the 2nd substrate 54 each other.The dielectric constant anisotropy Δ ε that forms the liquid crystal material of liquid crystal layer 60 is just (Δ ε > 0).In this liquid crystal material, be added with for making liquid crystal molecule become the chiral material of twisted-oriented.

Column spacer 61 is configured between the 1st substrate 51 and the 2nd substrate 54, gap is between the two remained to the element thickness (for example a few μ m) of regulation.These column spacers 61 are for example used the photoresist material and form.In the present embodiment, each column spacer 61 is pre-formed on the 1st substrate 51.

Fig. 4 (A) and Fig. 4 (B) are the schematic diagram of shape when the overlooking of column spacer is shown respectively.For example, shown in Fig. 4 (A), each column spacer 61 forms respectively the upwardly extending wire of the 1st side (in illustrated example be rectangular rectangular-shaped), and equally spaced configuration on the 2nd direction.In addition, the configuration space of column spacer 61 can not be also uniformly-spaced.In addition, for example, shown in Fig. 4 (B), each column spacer 61 can form respectively point-like (being square shape in illustrated example), is configured to equally spaced rectangular.In addition, the shape of each column spacer 61 is not limited to square shape, and configuration space can not be also uniformly-spaced.Even use the column spacer 61 of any one shape, from making the more stable angle of element thickness, more than 3.8% of territory, the total area occupied area total area while all wishing the overlooking of each column spacer 61 in the zone of the optical modulation for showing etc.

Fig. 5 is the schematic cross sectional views that the electric field that uses each electrode pair liquid crystal layer to apply is described.Fig. 5 (A) is the schematic diagram that the configuration of the 1st～4th electrode is shown with overlooking.Fig. 5 (B)～Fig. 5 (D) is the schematic diagram that the configuration of the 1st～4th electrode is shown with analysing and observe.The 1st electrode 52 and the 2nd electrode 55 are opposite each other, at both, in overlapping zone, dispose the 3rd electrode 58 and the 4th electrode 59.In addition, to prop up that a plurality of electrodes with the 4th electrode 59 prop up be that mode repeatedly to replace one by one configures to a plurality of electrodes of the 3rd electrode 58.

As shown in Figure 5 (B), by between the 1st electrode 52 and the 2nd electrode 55, applying voltage, can between two electrodes, produce electric field.As shown in the figure, electric field now is along the electric field of the thickness direction (element thickness direction) of the 1st substrate 51 and the 2nd substrate 54, i.e. " longitudinal electric field ".

In addition, as shown in Fig. 5 (C), by between the 3rd electrode 58 and the 4th electrode 59, applying voltage, can between two electrodes, produce electric field.As shown in the figure, electric field now is and the electric field of the direction of the 1st substrate 51 and the 2nd substrate 54 almost parallel separately, i.e. " transverse electric field ".Afterwards, sometimes also will use the pattern of such electric field to be called " IPS pattern ".

In addition, as shown in Fig. 5 (D), by between the 2nd electrode 55 relatively configuring across dielectric film 56 and the 3rd electrode 58 and the 4th electrode 59, applying voltage, can between two electrodes, produce electric field.As shown in the figure, electric field now is along the electric field of the direction with the 1st substrate 51 and the 2nd substrate 54 almost parallel separately, i.e. " transverse electric field ".After, sometimes also will use the pattern of such electric field to be called " FFS pattern ".

In the liquid crystal cell of present embodiment, under original state, the liquid crystal molecular orientation of liquid crystal layer 60 is the bent twisted state of exhibition.With respect to this, when using as mentioned above the 1st electrode 52 and the 2nd electrode 55 to produce longitudinal electric field, the state of orientation of the liquid crystal molecule of liquid crystal layer 60 is to the reverse twist state-transition.Afterwards, when using the 3rd electrode 58 and the 4th electrode 59 to produce transverse electric field (IPS pattern), the state of orientation of liquid crystal layer 60 changes to the bent twisted state of exhibition.In addition, even when using the 2nd electrode the 55, the 3rd electrode the 58, the 4th electrode 59 to produce transverse electric field (FFS pattern), the state of orientation of liquid crystal layer 60 is also similarly from the reverse twist state, to the bent twisted state of exhibition, to change.With the IPS pattern relatively in, the tendency that exists the FFS pattern can make the state of orientation of liquid crystal layer 60 change more equably.This is because also applied transverse electric field on each electrode of the 3rd electrode the 58, the 4th electrode 59.Therefore, from aperture opening ratio (transmissivity, contrast) aspect, consider, can say that the FFS pattern is more suitable.

The reason that can switch between the bent twisted state of exhibition and reverse twist state about the state of orientation of liquid crystal layer 60, investigated as follows.In the bent twisted state of exhibition, the liquid crystal molecule approximate horizontal ground of the substantial middle of the bed thickness direction of liquid crystal layer 60 is orientated, and, after by longitudinal electric field, becoming the reverse twist state, the liquid crystal molecule of the substantial middle of bed thickness direction tilts to vertical direction.Afterwards, transverse electric field by IPS pattern or FFS pattern, liquid crystal molecule to the substantial middle of the bed thickness direction of the liquid crystal layer 60 in the reverse twist state applies transverse electric field, open up the liquid crystal molecule of this substantial middle of the liquid crystal layer 60 in bent twisted state towards due director orientation, therefore again change to the bent twisted state of the exhibition as original state.Hence one can see that, and the longitudinal electric field of applying in a flexible way and transverse electric field can be to opening up bent twisted state and the reverse twist state is switched.

Then, an example of the manufacture method of liquid crystal cell is elaborated.

ITO film by the glass substrate to the ITO film carries out composition, makes the 1st substrate 51 with the 1st electrode 52.Can carry out by general photoetching technique the composition of ITO film herein.As the ITO engraving method, use wet etching (iron chloride).In the shape pattern of the 1st electrode 52 here, at extraction electrode, partly with in the part that is equivalent to display pixel remain with the ITO film.Similarly, the ITO film by the glass substrate to the ITO film carries out composition, makes the 2nd substrate 54 with the 2nd electrode 55.

Form column spacer 61 on the 1st electrode 52 of the 1st substrate 51.For example, be coated with transparent negative photosensitive resin (for example making spinner rotate for 30 seconds) by spinner on the one side of the 1st substrate 51, and carry out prebake (for example 100 ℃, 120 seconds).In addition, by adjusting the rotating speed of spinner, can in the scope of thickness 0.5 μ m～5 μ m left and right, carry out equably film forming.Also can replace with the slot coated device coating of spinner.Now, film forming arrives thickness 10 μ m left and right equably.After film forming, across the photomask with exposing patterns corresponding with the column spacer 61 of intended shape, utilize and take contact exposure machine that high-pressure mercury-vapor lamp is light source to the photosensitive resin film irradiation ultraviolet radiation.Conditions of exposure for example is made as with illumination 5.79mW/cm ²Irradiate 35 second (200mJ/cm ²).Afterwards, be impregnated in the tetramethylammonium hydroxide aqueous solution of concentration 1%, make thus photoresist develop, and rinsed with pure water, after drying substrates, cure with 220 ℃ of masters that carry out 30 minutes in dustless baking box.Form thus a plurality of column spacers 61 on the one side of the 1st substrate 51.

Form dielectric film 56 on the 2nd electrode 55 of the 2nd substrate 54.Now, in order at extraction electrode, partly not locate to form dielectric film 56, need to take measures.As its method, can list following method: partly locate to form resist at extraction electrode in advance, the method for being peeled off after forming dielectric film 56; Form the method etc. of dielectric film 56 by sputtering method etc. under the state that has covered the extraction electrode part by metal mask etc.In addition, as dielectric film 56, can list the inorganic insulating membranes such as organic insulating film or silicon oxide film or silicon nitride film and their combination etc.Here, by acrylic acid series organic insulating film and silicon oxide film (SiO ₂Film) stacked film is as dielectric film 56.

Locate to paste heat-resistant film (Kapton Tape) in extraction electrode part (terminal part), be coated with the material liquid of organic dielectric film at this state backspin.For example, with 2000rpm, rotating under the condition in 30 seconds, obtaining the thickness of 1 μ m.In dustless baking box, it is cured to (for example, 220 ℃, 1 hour).Be pasted with under the state of heat-resistant film by sputtering method (alternating current discharge) formation SiO ₂Film.For example, by base plate heating to 80 ℃, form

Herein, when peeling off heat-resistant film, can be by organic insulating film, SiO ₂Film is peeled off together neatly.Afterwards, toasted (for example, 220 ℃, 1 hour) in dustless baking box.This is in order to improve SiO ₂The insulativity of film and the transparency.Although be not to form SiO ₂Film, but by forming SiO ₂Film, can improve adhesion and the composition of the ITO film formed on it, so be preferably formed SiO ₂Film.And insulativity also improves.On the other hand, also can consider not form organic insulating film and only pass through SiO ₂Film obtains the method for insulativity, but now, due to SiO ₂Film easily becomes Porous, therefore preferably thickness is guaranteed for

Left and right.In addition, also can become the stacked film with SiNx.In addition, as the formation method of inorganic insulating membrane, although narrated sputtering method, also can use the formation methods such as vacuum vapour deposition, ion beam method, CVD method (chemical vapour deposition technique).

Then, form the 3rd electrode 58 and the 4th electrode 59 on dielectric film 56.Specifically, at first on dielectric film 56, by sputtering method (alternating current discharge), form the ITO film.For example, by its base plate heating to 100 ℃, on whole, form approximately The ITO film of left and right.By general photoetching technique, this ITO film is carried out to composition.As photomask now, use the photomask with shading light part corresponding with the comb-like electrode shown in above-mentioned Fig. 5.About comb-like electrode, for example can establish the width that electrode props up is that 20 μ m～30 μ m, electrode gap are 20 μ m～200 μ m.In addition, if partly locate also there is no pattern at above-mentioned extraction electrode, also can the ITO film of downside be removed by etching, therefore use and partly locate also to form figuratum photomask at extraction electrode.

The 1st substrate 51 and the 2nd substrate 54 of making as mentioned above cleaned.Specifically, at first washed (scrub or hydro-peening, pure water clean), carried out the UV cleaning after having removed moisture, finally carried out the IR drying.

Then, form respectively

alignment films

53,57 on the 1st substrate the 51, the 2nd substrate

54.As alignment films

53,57, for example use polyimide film, the side chain density that this polyimide film has reduced the material used usually used as vertical alignment layer obtains.The material liquid (oriented material) of alignment films is applied to the 1st substrate the 51, the 2nd substrate 54 one side separately, in dustless baking box, they is cured to (for example 160 ℃, 1 hour).Coating process as the material liquid of alignment films, can be used flexographic printing, ink jet printing or spin-coating method.Although used spin-coating method here, even if use other mode result, be also same.The thickness of

alignment films

53,57 is for example

The friction treatment of then, each

alignment films

53,57 being carried out as orientation process.The amount of being pressed into during friction for example is set as 0.8mm.Thus, each

alignment films

53,57 can make liquid crystal molecule produce the tilt angle of 20 °～60 ° of left and right.

Then, by the 1st substrate 51 and the 2nd substrate 54 laminatings.Printing and sealing material in advance on the 1st substrate 51.Then, between the 1st substrate 51 and the 2nd substrate 54, inject liquid crystal material, form thus liquid crystal layer 60.For example add CB15 as chiral material in liquid crystal material.

Complete thus the liquid crystal cell of present embodiment.Such liquid crystal cell of present embodiment is when completing, and liquid crystal layer 60 is oriented to the bent twisted state of exhibition.Now, transmissivity (or reflectivity) is lower, becomes the outward appearance of darker state.And, when liquid crystal layer 60 is applied to longitudinal electric field, the orientation transition of liquid crystal layer 60 is the reverse twist state, also maintain this state after having closed electric field.Now, transmissivity (or reflectivity) is higher, becomes the outward appearance of brighter state.Then, when liquid crystal layer 60 is applied to transverse electric field, the orientation of liquid crystal layer 60 changes to the bent twisted state of exhibition again, also maintains this state after closing electric field.Contrast now has following trend: in the time of near tilt angle is 45 °, contrast is the highest, along with tilt angle step-down contrast also reduces.Particularly when tilt angle is less than 20 °, contrast significantly reduces, and poor (or reflectivity is poor) of opening up the transmissivity of bent twisted state and reverse twist state almost disappears, and confirms the situation that demonstration property is inadequate.

Then, the structure example of the liquid crystal indicator of the low-power consumption the carried out driving of the Memorability of having utilized above-mentioned liquid crystal cell to have described.

Fig. 6 is the figure that the structure example of liquid crystal indicator schematically is shown.Liquid crystal indicator shown in Fig. 6 is by a plurality of pixel section 74, to be arranged in rectangular and the liquid crystal indicator pure matrix type that forms has been used above-mentioned liquid crystal cell as each pixel section 74.Specifically, liquid crystal indicator is configured to and comprises: the m root control line B1～Bm extended on directions X; These control lines B1～Bm is provided to the driver 71 of control signal; The n root control line A1～An extended on Y-direction across with control line B1～Bm respectively; These control lines A1～An is provided to the driver 72 of control signal; The n root control line C1～Cn and the D1～Dn that on Y-direction, extend across with control line B1～Bm respectively; These control lines C1～Cn and D1～Dn are provided to the driver 73 of control signal; And the pixel section 74 that is arranged on each intersection point place of control line B1～Bm and control line A1～An.

Each control line B1～Bm, A1～An, C1～Cn and D1～Dn form such as the nesa coatings such as ITO by forming striated.The part that control line B1～Bm and A1～An intersect is as the 1st above-mentioned electrode 52 and the 2nd electrode 55 performance functions (with reference to Fig. 3).In addition, control line C1～Cn is arranged in the zone corresponding with each pixel section 74, props up (omitting diagram in Fig. 6) with the electrode of comb teeth-shaped as the 3rd electrode 58 and is connected.Equally, control line D1～Dn is arranged in the zone corresponding with each pixel section 74, props up (omitting diagram in Fig. 6) with the electrode of comb teeth-shaped as the 4th electrode 59 and is connected.

As the driving method of the liquid crystal indicator of structure shown in Fig. 6, can consider the whole bag of tricks.For example,, to according to control line B1, B2, B3 ... every line shows that the method (line drives method successively) of rewriting describes.Now, as long as the pixel section 74 that hope is carried out to relatively bright demonstration (reverse twist state) applies longitudinal electric field, the pixel section 74 that hope is carried out to relatively dark demonstration (opening up bent twisted state) applies transverse electric field and gets final product.

For example, control line B1 is applied to the square-wave voltage (for example about 5V and be 150Hz) of the degree of the transformation that can not produce state of orientation, control line A1～An, C1～Cn and D1～Dn are applied and synchronize with it or the square-wave voltage of the threshold voltage left and right of the half period that staggers (for example 5V left and right and be 150Hz).

At length say, in control line A1～An, with hope, carrying out control line corresponding to the pixel section 74 of brighter demonstration, apply and the stagger square-wave voltage of half period of the square-wave voltage that imposes on control line B1.Now, control line C1～Cn and D1～Dn are not applied to voltage.Thus, become the actual state that has applied the voltage (longitudinal electric field) of 10V left and right of the liquid crystal cell of pixel section 74.If this voltage is more than saturation voltage, make the transformation of liquid crystal layer 60 generation state of orientation, can change the transmissivity of this pixel section 74.On the other hand, the control line for corresponding with the pixel section 74 that does not need change to show in control line A1～An, apply the square-wave voltage of synchronizeing with the square-wave voltage that imposes on control line B1.Now control line C1～Cn and D1～Dn are not applied to voltage yet.Thus, in this pixel section 74, become the alive state of in fact not executing.Therefore, do not produce the transformation of state of orientation in liquid crystal layer 60, transmissivity does not change.

In addition, in control line C1～Cn and D1～Dn, with hope, showing slinkingly control line corresponding to the pixel section 74 that shows, apply and the stagger square-wave voltage of half period of the square-wave voltage that imposes on control line B1.Now control line A1～An is not applied to voltage.Thus, become the actual state that has applied the voltage (transverse electric field) of 10V left and right of the liquid crystal cell of pixel section 74.If this voltage is more than saturation voltage, make the transformation of liquid crystal layer 60 generation state of orientation, can change the transmissivity of this pixel section 74.On the other hand, the control line for corresponding with the pixel section 74 that does not need change to show in control line C1～Cn and D1～Dn, apply the square-wave voltage of synchronizeing with the square-wave voltage that imposes on control line B1.Now control line A1～An is not applied to voltage yet.Thus, in this pixel section 74, become the alive state of in fact not executing.Therefore, do not produce the transformation of state of orientation in liquid crystal layer 60, transmissivity does not change.

By according to control line B2, B3 ... carry out successively driving as above, can carry out the dot matrix demonstration.The show state of rewriting by driving as above can semi-permanently keep.When rewriting this demonstration, as long as again from control line B1, carry out above-mentioned control.In addition, although show the example that applies the present invention to so-called pure matrix liquid crystal display device here, also can apply the present invention to use the active array type LCD of thin film transistor (TFT) etc.In the situation that active array type LCD does not need the every lines such as control line B1 are rewritten, therefore can shorten the rewriting time.In addition, the voltage more than 2 times of threshold value can also be applied, therefore rewriting more at a high speed can be carried out.Yet, because be exists the electrode that transverse electric field is used and longitudinal electric field is used on the substrate of a side, therefore every 1 pixel needs two thin film transistor (TFT)s etc.

(embodiment 1)

Manufactured the liquid crystal cell of the column spacer with the wire of extending in one direction.In the present embodiment, on one-sided substrate, having formed is highly the column spacer of 4 μ m left and right.When the photosensitive resin coating material, the rotating speed of spinner is made as to 600rpm.In addition, use with the shape of column spacer accordingly opening become the negativity photomask (live width is that 40 μ m, distance between centers of tracks are 400 μ m) of wire, expose.Operation in addition is identical with above-mentioned embodiment.Preferably in the part of the primary seal material for the sealing liquid crystal layer, do not form the column spacer of this wire.Then, as alignment films, used polyimide film, this polyimide film is adjusted into the side chain density of the material that uses usually used as vertical alignment layer can produce suitable tilt angle and obtain.Stoving temperature is set between 160 ℃～260 ℃.As the formation method of alignment films, can use flexographic printing, ink jet printing or spin-coating method.Although used spin-coating method here, even if use other mode results, be also identical.The thickness of alignment films is

Then carried out friction treatment.The amount of being pressed into during friction is 0..8mm, twist angle

It is 70 °.Element thickness d is 4 μ m.Added chiral material at the liquid crystal material injected.The addition of chiral material is d/p=0.20～0.53.About polarization plates, with the axis of homology each other roughly the axis of homology of quadrature and each polarization plates with frictional direction, become the mode of 15 ° to configure.

Fig. 7 (A)～Fig. 7 (D) is the figure of microscopic examination picture that the liquid crystal cell of embodiment 1 is shown.In each figure, seem that relatively bright zone is corresponding to exhibition bent twisted state (initial orientation), seem that darker zone is corresponding to reverse twist state (zone of switching by longitudinal electric field).In the past, the border entanglement in two zones and become zigzag, when examining this part, observe following situation: the spherical sept of random scatter has conjointly formed regional boundary line, depend on the position of spherical sept and keep the orientation remember condition.On the other hand, as shown in Fig. 7 (A)～Fig. 7 (D), in embodiment 1, observe following situation: the transformation from the reverse twist state to the bent twisted state of exhibition is blocked along the column spacer of wire.At length say, according to the order of Fig. 7 (A), Fig. 7 (B), Fig. 7 (C), Fig. 7 (D), the state when with time sequencing, showing electric field and apply.Although also relevant with the electrode position for generation of longitudinal electric field, but, boundary portion between bearing of trend by the dividing wall that makes to be realized by column spacer and the zone of the zone of opening up bent twisted state and reverse twist state (, can apply the end of the electrode of longitudinal electric field) consistent, can make the zone of these two orientations become discontinuous state, can utilize column spacer to block the transformation of state of orientation two-wayly, can improve the Memorability of state of orientation.Liquid crystal cell for this embodiment 1, in order to investigate the stability that keeps state of orientation, with 90 ℃ of heating, within about 30 minutes, observe, confirming each state of orientation (opening up bent twisted state or reverse twist state) stably keeps, before and after heating, the boundary portion place between exhibition bent warped regions and reverse twist zone also do not change (with reference to Fig. 7 (D)).In addition we know, do not see the disclination line of observing fully in the liquid crystal cell of embodiment 1 in the bent twisted-oriented of the exhibition zone of liquid crystal cell in the past.Known disclination line is be connected and formed by the spherical sept as gap control material, and, in the liquid crystal cell of the present embodiment 1 that does not need gap control material, can eliminate the disclination line.

(embodiment 2)

Manufactured the liquid crystal cell with the column spacer that is configured to rectangular point-like.In the present embodiment, on one-sided substrate, having formed is highly the column spacer of 4 μ m left and right.When the photosensitive resin coating material, the rotating speed of spinner is made as to 600rpm.In addition, use with the shape of column spacer accordingly opening become the negativity photomask of point-like (spot size be

Dot density is 3.8% left and right), expose.Operation in addition is identical with above-mentioned situation.Preferably in the part of the primary seal material for the sealing liquid crystal layer, do not form the column spacer of this point-like.Creating conditions in addition is identical with the situation of embodiment 1.

Fig. 8 is the figure of microscopic examination picture that the liquid crystal cell of embodiment 2 is shown.In the drawings, seem that relatively bright zone is corresponding to exhibition bent twisted state (initial orientation), seem that darker zone is corresponding to reverse twist state (zone of switching by longitudinal electric field).Known according to Fig. 8, the boundary line of opening up the zone of the zone of bent twisted state and reverse twist state becomes linearity clearly.Here known: the boundary line of observing in Fig. 8 is roughly consistent with the end of electrode for applying longitudinal electric field, like this, the position of the column spacer by making point-like and the position consistency of electrode, can make the boundary line of opening up bent twisted state and reverse twist state become clear.In addition, in order to obtain the configuration of column spacer as above, as long as adjust accordingly the position of photomask in the exposure when forming column spacer with the position of electrode, need not append especially operation.Although the situation that is linearity to the end shape of electrode here is illustrated, the end shape of electrode can be also curve-like.Now, as long as use the photomask that is designed to configure according to the position of curve the column spacer of point-like.In addition, even the position slight modification of column spacer, as long as make dot density roughly the same, just can not exert an influence to performance and display quality.In addition, about the position of column spacer now, preferably, towards the column spacer of the inboard ionization electrode of electrode end bee-line, be configured in ionization electrode end 100 μ m with interior position.In addition, as shown in the embodiment of Fig. 8, if column spacer carries out planar configuration with 100 μ m spacings, the whichever position all meets above-mentioned condition, does not therefore need to make electrode consistent accurately with the position of column spacer.Even at the gap ratio 100 μ m of column spacer in large or irregular situation, if adopt following configuration, no problem, that is: the end of the electrode from forming pixel towards inboard 100 μ m with interior zone, the column spacer at bee-line place is consistent with the end shape of electrode.In addition, as shown in the present embodiment 2, in the situation that used the column spacer of point-like, with the situation of the column spacer that has used the wire as embodiment 1, compare, more easily inject liquid crystal material.This is because hinder the mobile key element of liquid crystal material few.

As mentioned above, according to present embodiment and each embodiment, the Memorability of liquid crystal cell under hot environment of having utilized the transformation between two kinds of state of orientation can be improved, and the reduction of the display quality that caused by the disclination line can be prevented.

In addition, the manufacturing process of liquid crystal cell is basically roughly the same with the manufacturing process of general liquid crystal cell and factor that cause cost to rise is few.That is, can utilize the manufacturing technology identical with general liquid crystal cell to be manufactured at low cost.

In addition, in the liquid crystal cell of present embodiment etc., do not need electric power when demonstration is rewritten, therefore can realize that super low-power consumption drives, can realize being suitable for that transmission-type shows, the demonstration of any one situation of reflection-type in showing yet.Particularly when being applied to the reflection-type demonstration, with the obvious advantage.

In addition, due to can applications exploiting the driving method (line rewriting method successively etc.) of Memorability of state of orientation, therefore do not need to use the switching devices such as thin film transistor (TFT), can carry out jumbo dot matrix demonstration by pure matrix display.Therefore, can realize that large capacity shows with low cost.

In addition, the invention is not restricted to the content of above-mentioned embodiment, can carry out various distortion in the scope of main idea of the present invention and implement.For example, in above-mentioned embodiment etc., as the object lesson of orientation process, enumerate friction treatment, but also can use orientation process (for example, optical alignment method, inclination vapour deposition method etc.) in addition.In addition, the example that the value conditions of enumerating in explanation etc. also only are applicable to, needn't be defined in this.In addition, can in forming the liquid crystal material of liquid crystal layer, add can polymerization under the effect of ultraviolet ray etc. material (monomer), and make above-mentioned monomer polymerization by irradiation ultraviolet radiation etc. after between substrate, injecting liquid crystal material.Now, can further improve the Memorability of state of orientation.

Claims

1. a liquid crystal cell, this liquid crystal cell comprises:

The 1st substrate and the 2nd substrate that relatively configure, the 1st substrate and the 2nd substrate one side separately have been implemented orientation process;

Be arranged on the liquid crystal layer between the one side of the one side of described the 1st substrate and described the 2nd substrate; And

Be arranged on a plurality of column spacers between the one side of the one side of described the 1st substrate and described the 2nd substrate,

About described the 1st substrate and described the 2nd substrate, the direction of described orientation process is set to the 1st state of orientation of the liquid crystal molecule distortion on the 1st direction that produces described liquid crystal layer, and, described the 1st substrate and described the 2nd substrate respectively with the interface of described liquid crystal layer, the tilt angle that is given to the liquid crystal molecule of this liquid crystal layer is more than 20 °

Described liquid crystal layer contains chiral material, and this chiral material has following character: the 2nd state of orientation that produces the distortion on the 2nd direction with described the 1st opposite direction of described liquid crystal molecule.

2. liquid crystal cell according to claim 1, wherein,

Described a plurality of column spacer has respectively the profile of wire or point-like when overlooking.

3. liquid crystal cell according to claim 1 and 2, wherein,

This liquid crystal cell also comprises voltage applying unit, and this voltage applying unit applies voltage in order to produce electric field to described liquid crystal layer,

Produce electric field by described voltage applying unit on the direction substantially vertical with described the 1st substrate and described the 2nd substrate one side separately, make thus described liquid crystal layer change to described the 1st state of orientation, by on the direction with described the 1st substrate and described the 2nd a substrate almost parallel separately, producing electric field, make thus described liquid crystal layer change to described the 2nd state of orientation.

4. a liquid crystal indicator, this liquid crystal indicator has a plurality of pixel section, and the other right to use of the plurality of pixel portion requires the described liquid crystal cell of any one in 1～3 and forms.