JP2005181725A - Liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display element in which mono-domain alignment of a ferroelectric liquid crystal is obtained without forming an alignment defect such as a double-domain, and which is excellent in alignment stability and keeps the alignment unchanged irrespective of a change in temperature in the liquid crystal display element using the ferroelectric liquid crystal. <P>SOLUTION: The construction of the liquid crystal display element to be provided is characterized by placing a projecting and recessing substrate with a first substrate, an electrode layer formed on the first substrate and a projecting and recessing pattern and a counter substrate with a second substrate, an electrode layer formed on the second substrate and an alignment layer having alignment controllability and formed on the electrode layer in such a way that the projecting and recessing pattern on the projecting and recessing substrate and the alignment layer on the counter substrate are opposite to each other, and interposing the monostable ferroelectric liquid crystal between the projecting and recessing substrate and the counter substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display element in which the orientation of ferroelectric liquid crystal is controlled.

  Liquid crystal display elements have been widely used from large displays to portable information terminals because of their thinness and low power consumption, and their development is actively underway. So far, liquid crystal display elements have been developed and put to practical use, such as TN mode, STN multiplex drive, and active matrix drive using thin layer transistors (TFTs) for TN, but these use nematic liquid crystals. In addition, the response speed of the liquid crystal material is as slow as several ms to several tens of ms, and it cannot be said that it is sufficiently compatible with moving image display.

  Ferroelectric liquid crystal (FLC) is a liquid crystal suitable for high-speed devices because its response speed is as short as μs order. Ferroelectric liquid crystal is widely known as a bistable one proposed by Clark and Lagerwal, which has two stable states when no voltage is applied (FIG. 6), but is limited to switching in two states, light and dark. However, although it has a memory property, it has a problem that gradation display cannot be performed.

In recent years, the state of a liquid crystal layer when a voltage is not applied has been stabilized in one state (hereinafter referred to as “monostable”). ) Is continuously changed, and the transmitted light intensity is analog-modulated so that gradation display is possible (Non-Patent Document 1, FIG. 6). As the liquid crystal exhibiting such monostability, a ferroelectric liquid crystal that changes phase with the cholesteric phase (Ch) -chiral smectic C phase (SmC ^* ) and does not pass through the smectic A phase (SmA) is used.

  Ferroelectric liquid crystals are more difficult to align due to higher molecular ordering than nematic liquid crystals, and defects such as zigzag defects and hairpin defects are likely to occur. Such defects cause a decrease in contrast due to light leakage. Become. In particular, in a ferroelectric liquid crystal that does not pass through the SmA phase, two regions having different layer normal directions (hereinafter referred to as “double domain”) are generated (FIG. 7). Such a double domain becomes a display which is reversed in black and white at the time of driving, which is a big problem (FIG. 8). As a method for improving the double domain, there is known an electric field applied slow cooling method in which a liquid crystal cell is heated to a temperature equal to or higher than a cholesteric phase and gradually cooled while a DC voltage is applied (Non-Patent Document 2). When the temperature rises again above the phase transition point, alignment disturbance occurs, and there is a problem that alignment disturbance occurs in a portion where the electric field between the pixel electrodes does not act.

  On the other hand, as a method for improving the alignment defect of the ferroelectric liquid crystal, which does not have monostability, Patent Document 1 and Patent Document 2 have a pair of substrates bonded via stripe-shaped barrier ribs. Discloses a method for improving the alignment state of the ferroelectric liquid crystal by enclosing the ferroelectric liquid crystal in a space formed by the above method. FIG. 9 shows an example of a conventional simple matrix type liquid crystal display element. 9B to 9E are plan views of FIG. 9A, and the alignment film 103 and the liquid crystal layer 105 are omitted. In the liquid crystal display device according to this method, as shown in FIG. 9A, an electrode layer 102 and an alignment film 103 are formed on opposite surfaces of a pair of substrates 101, respectively, and a stripe-shaped partition wall 104 is formed. Is. The width of the partition wall 104 is about the width of the portion between the electrode layers 102 where the electrode layer 102 is not formed. The thickness of the partition wall 104 is substantially the same as that of the liquid crystal layer 105. Is about the width of the electrode layer 102. In such a liquid crystal display element, it is possible to control the alignment of the ferroelectric liquid crystal by partitioning the liquid crystal layer with partition walls. However, when the alignment direction 106 of the alignment film is parallel to the extending direction of the partition walls 104 ( FIG. 9B) has a problem that liquid crystal cracks may occur. This is presumably because the liquid crystal layer is partitioned by the partition walls, so that the volume shrinkage due to the temperature change of the ferroelectric liquid crystal cannot be accommodated in the layer. On the other hand, when the alignment direction 106 is perpendicular to the extending direction of the partition wall 104 (FIG. 9C), there is an advantage that there is no liquid crystal cracking because there is no obstacle to the flow of the ferroelectric liquid crystal. There is a problem that alignment defects such as domains are likely to occur.

  Therefore, in Patent Document 3, the orientation of the alignment direction 106 and the extension direction of the partition wall 104 is set to 50 ± 20 ° (FIG. 9D), thereby controlling the alignment of the ferroelectric liquid crystal and causing the liquid crystal cracks. A method of preventing is disclosed. In Patent Document 4, the partition 104 is formed in, for example, a zigzag shape (FIG. 9E) to control the orientation of the ferroelectric liquid crystal, and two domains are alternately and periodically formed. A method is disclosed. However, in the method of providing the partition wall, the ferroelectric liquid crystal confined by the partition wall shrinks in volume as the temperature changes, and the partition wall shrinks following the ferroelectric liquid crystal corresponding to the stress generated between the substrates. If this is not possible, voids are generated in the liquid crystal display element. When a gap is generated in the liquid crystal display element in this way, a portion without liquid crystal is formed in the liquid crystal display element. When the liquid crystal display element is driven, the portion is not driven and accurate display cannot be performed. It causes deterioration of various characteristics such as a decrease in contrast.

  Furthermore, a method for improving the alignment state of the ferroelectric liquid crystal by forming a concavo-convex shape in the portion between the electrode layers and where the electrode layer is not formed instead of the partition walls as described above is also disclosed ( Patent Document 5). However, even in this method, it is difficult to control the alignment of the ferroelectric liquid crystal without generating voids in the liquid crystal display element due to the volume shrinkage of the ferroelectric liquid crystal. Furthermore, in this method, an alignment film is formed on both of the two substrates, and this alignment film cancels the effect of the unevenness, so that there is a problem that the double domain cannot be eliminated.

  In addition, none of the above methods suppresses the occurrence of alignment defects in ferroelectric liquid crystal having monostability, and a method for improving the double domain is not described.

  On the other hand, in recent years, full-color liquid crystal display elements have been actively developed. As a method for realizing color display, there are generally a color filter method and a field sequential color method. In the color filter system, a white light source is used as a backlight, and color display is realized by attaching R, G, B micro color filters to each pixel. On the other hand, the field sequential color system switches the backlight to R, G, B, R, G, B ... in time, and opens and closes the black and white shutter of the ferroelectric liquid crystal to synchronize with it, and the afterimage effect of the retina Thus, the colors are mixed temporally to realize color display. In this field sequential color system, color display is possible with one pixel, and it is not necessary to use a color filter with low transmittance. Therefore, the color display can be made high definition, and low power consumption and low cost can be realized. Useful in terms. However, since the field sequential color system divides one pixel in time, in order to obtain good moving image display characteristics, it is necessary that the liquid crystal as a black and white shutter has high-speed response. This problem can be solved by using a ferroelectric liquid crystal, but the ferroelectric liquid crystal has a problem that alignment defects are likely to occur as described above, and has not been put into practical use.

JP 7-318912 A Japanese Patent Laid-Open No. 7-159792 JP 2000-66176 A JP 2001-51278 A Japanese Patent No. 2715209 NONAKA, T., LI, J., OGAWA, A., HORNUNG, B., SCHMIDT, W., WINGEN, R., and DUBAL, H., 1999, Liq. Cryst., 26, 1599. PATEL, J., and GOODBY, J. W., 1986, J. Appl. Phys., 59, 2355.

  The present invention has been made in view of the above problems, and in a liquid crystal display element using a ferroelectric liquid crystal, a monodomain alignment of the ferroelectric liquid crystal is obtained without forming an alignment defect such as a double domain. The main object of the present invention is to provide a liquid crystal display element that is capable of maintaining the orientation with respect to temperature change and having excellent orientation stability.

  In order to achieve the above object, the present invention provides a concavo-convex substrate having a first substrate, an electrode layer and a concavo-convex pattern formed on the first substrate, a second substrate, and the second substrate. The counter substrate having the formed electrode layer and the alignment film formed on the electrode layer and having alignment ability is disposed so that the concavo-convex pattern of the concavo-convex substrate and the alignment film of the counter substrate face each other, and Provided is a liquid crystal display element characterized in that a dielectric liquid crystal exhibiting monostability is sandwiched between an uneven substrate and the counter substrate.

  According to the present invention, a concavo-convex pattern is formed on the surface of the concavo-convex substrate facing the counter substrate, an alignment film is formed on the surface of the counter substrate facing the concavo-convex substrate, and the ferroelectric liquid crystal is sandwiched therebetween. As a result, the ferroelectric liquid crystal can be aligned without forming alignment defects such as double domains. Moreover, since the alignment treatment is performed using the alignment film without using the voltage application slow cooling method, the alignment can be maintained with respect to the temperature change, and the occurrence of alignment defects such as double domains can be suppressed. Has the advantage. Furthermore, since the ferroelectric liquid crystal exhibits monostability, the effect of the configuration of the present invention becomes remarkable.

  In the present invention, it is preferable that the concavo-convex pattern is composed of lattice-shaped or striped convex portions.

  In the above invention, it is preferable that the lattice-shaped or stripe-shaped convex portion is formed so that a linear portion of the lattice-shaped or stripe-shaped convex portion intersects the alignment direction of the alignment film. Furthermore, it is preferable that the smaller one of the angles formed by the linear portions of the lattice-shaped convex portions and the alignment direction of the alignment film is within a range of 30 ° to 45 °. This is because the alignment of the ferroelectric liquid crystal can be effectively controlled.

  In the present invention, it is preferable that the electrode layer or the uneven pattern of the uneven substrate is in direct contact with the ferroelectric liquid crystal. In the case where an alignment film is also formed on the concavo-convex substrate side, the effect of the concavo-convex pattern is canceled by this alignment film, which may adversely affect the alignment control of the ferroelectric liquid crystal. It is preferable that no alignment film is formed on the electrode layer, and the electrode layer or the uneven pattern is in direct contact with the ferroelectric liquid crystal.

  Further, in the present invention, the ferroelectric liquid crystal preferably does not have a smectic A phase in the phase series. As described above, the ferroelectric liquid crystal having no smectic A phase in the phase series is likely to cause alignment defects such as a double domain, but the double domain is formed by sandwiching the ferroelectric liquid crystal between the concavo-convex pattern and the alignment film. This is because the occurrence of alignment defects such as the above can be suppressed, and the effect of the configuration of the present invention becomes remarkable.

  Furthermore, in the present invention, the alignment film is preferably a photo-alignment film. This is because the photo-alignment process is a non-contact alignment process, which is useful in that it does not generate static electricity or dust and can quantitatively control the alignment process.

  In the present invention, it is preferable that the height of the convex portion is smaller than the thickness of the liquid crystal layer formed by sandwiching the ferroelectric liquid crystal.

  Furthermore, the liquid crystal display element of the present invention is preferably driven by a field sequential color system. The liquid crystal display device has a high response speed and can align the ferroelectric liquid crystal without causing alignment defects. Therefore, the liquid crystal display element can be driven by the field sequential color method, and has a wide viewing angle and high-definition video. This is because display can be realized.

  The liquid crystal display element of the present invention can align ferroelectric liquid crystal without forming alignment defects such as zigzag defects, hairpin defects, double domains, etc., and has alignment stability that hardly causes alignment disorder due to temperature change. There is an effect that an excellent liquid crystal display element can be obtained.

Hereinafter, the liquid crystal display element of the present invention will be described in detail.
The liquid crystal display element of the present invention includes a first substrate, an uneven substrate having an electrode layer and an uneven pattern formed on the first substrate, a second substrate, and an electrode formed on the second substrate. A counter substrate having a layer and an alignment film formed on the electrode layer and having alignment ability is disposed so that the concavo-convex pattern of the concavo-convex substrate and the alignment film of the counter substrate face each other. A ferroelectric liquid crystal exhibiting monostability is sandwiched between opposing substrates.

  Such a liquid crystal display element of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing an example of the liquid crystal display element of the present invention, and FIG. 2 is a schematic sectional view. As shown in FIG. 2, the liquid crystal display element of the present invention has a concavo-convex substrate 11 and a counter substrate 12, and a ferroelectric liquid crystal is sandwiched between the concavo-convex substrate 11 and the counter substrate 12, and the liquid crystal layer 5 Is configured. The uneven substrate 11 has a first substrate 1a, an electrode layer 2d formed on the first substrate 1a, and an uneven pattern 3 formed on the electrode layer 2d. On the other hand, the counter substrate 12 includes a second substrate 1b, electrode layers 2a and 2c formed on the second substrate 1b, and an alignment film 4 formed on the electrode layers 2a and 2c. In FIG. 1, the liquid crystal layer and the alignment film are omitted.

  As described above, the liquid crystal display element of the present invention forms a concavo-convex pattern on the surface of the concavo-convex substrate facing the counter substrate, and forms an alignment film on the surface of the counter substrate facing the concavo-convex substrate. Generation of alignment defects such as defects and double domains can be suppressed, and uniform alignment of the ferroelectric liquid crystal can be obtained. In addition, since the present invention aligns ferroelectric liquid crystal without using a voltage application slow cooling method, alignment disorder due to temperature changes, which is a problem of the voltage application slow cooling method, is less likely to occur and alignment stability is improved. It has the advantage of being excellent. The reason why a good alignment state can be obtained by forming a concavo-convex pattern on the concavo-convex substrate side and forming an alignment film on the counter substrate side is not clear. It is considered that this is due to the difference in the interaction between the alignment regulating force due to the concavo-convex pattern and the ferroelectric liquid crystal.

  In addition, the ferroelectric liquid crystal used in the present invention exhibits monostability, and has a property of having only one stable state when no voltage is applied, for example, as shown in FIG. In such a ferroelectric liquid crystal, two regions (double domains) having different layer normals are likely to be generated as shown in FIG. The occurrence of defects can be suppressed.

  In the liquid crystal display element of the present invention, for example, as shown in FIG. 1, one substrate is a TFT substrate in which thin film transistors (TFTs) 7 are arranged in a matrix, and the other substrate is a common electrode having a common electrode 2d formed on the entire surface. The electrode substrate is preferably a combination of these two substrates. An active matrix liquid crystal display element using such a TFT will be described below.

  In FIG. 1, the concavo-convex substrate 11 is a common electrode substrate with the electrode layer being the common electrode 2d, while the counter substrate 12 is composed of the x electrode 2a, the y electrode 2b, and the pixel electrode 2c. It is a TFT substrate. In such a liquid crystal display element, the x electrode 2a and the y electrode 2b are respectively arranged vertically and horizontally. By applying a signal to these electrodes, the TFT element 7 is operated to drive the ferroelectric liquid crystal. be able to. A portion where the x electrode 2a and the y electrode 2b intersect with each other is insulated by an insulating layer (not shown), and the signal of the x electrode 2a and the signal of the y electrode 2b can be operated independently. A portion surrounded by the x electrode 2a and the y electrode 2b is a pixel which is a minimum unit for driving the liquid crystal display element of the present invention, and at least one TFT element 7 and a pixel electrode 2c are formed in each pixel. ing. In the liquid crystal display element of the present invention, the TFT element 7 of each pixel can be operated by sequentially applying a signal voltage to the x electrode 2a and the y electrode 2b.

  Furthermore, the liquid crystal display element of the present invention can be used as a color display by forming a micro color filter in which TFTs 7 are arranged in a matrix between the common electrode 2d of the concavo-convex substrate 11 and the first substrate 1a.

  1 and 2, the side on which the common electrode 2d is formed is the concavo-convex substrate 11, and the side on which the TFT element 7, the pixel electrode 2c and the like are formed is the counter substrate 12, but the liquid crystal display element of the present invention Is not limited to such a configuration, and the side on which the common electrode is formed may be a counter substrate, and the side on which a TFT element, a pixel electrode, or the like is formed may be an uneven substrate. Further, in FIG. 2, the concave / convex pattern 3 is formed on the electrode layer 2d, but in the present invention, the concave / convex pattern may be formed between the first substrate and the electrode layer.

In the liquid crystal display element of the present invention, for example, as shown in FIG. 2, polarizing plates 6a and 6b may be provided outside the first substrate 1a and the second substrate 1b. Only light that is polarized and polarized in the alignment direction of the liquid crystal molecules can be transmitted. The polarizing plates 6a and 6b are arranged with the polarization direction twisted by 90 °. This controls the direction of the optical axis of the liquid crystal molecules and the magnitude of the birefringence in the voltage non-applied state and the applied state, and creates a bright state and a dark state by using the ferroelectric liquid crystal molecules as a black and white shutter. Can do. For example, when no voltage is applied, the polarizing plate 6a is installed so as to be aligned with the orientation of the liquid crystal molecules, so that the light transmitted through the polarizing plate 6a cannot rotate the polarization direction by 90 °, and the polarizing plate 6b It is cut off and darkened. On the other hand, in the voltage application state, the orientation of the liquid crystal molecules is set so as to have an angle θ (preferably θ = 45 °) with respect to the polarizing plates 6a and 6b. It twists and passes through the polarizing plate 6b and becomes bright. As described above, the liquid crystal display element of the present invention uses the ferroelectric liquid crystal as a black and white shutter, and thus has an advantage that the response speed can be increased.
Each component of the liquid crystal display element of the present invention will be described in detail below.

1. Constituent Member of Liquid Crystal Display Element (1) Uneven substrate First, an uneven substrate will be described. In the present invention, the concavo-convex substrate has a first substrate, an electrode layer and a concavo-convex pattern formed on the first substrate. As the configuration of the concavo-convex substrate, as described above, the first substrate, the electrode layer, and the concavo-convex pattern may be sequentially formed, or the first substrate, the concavo-convex pattern, and the electrode layer may be sequentially formed.

In the present invention, it is preferable that the electrode layer or the uneven pattern of the uneven substrate is in direct contact with the ferroelectric liquid crystal. That is, it is preferable that the surface of the concavo-convex substrate facing the counter substrate is not subjected to an alignment treatment. According to the present invention, as described above, a concavo-convex pattern is formed on the surface of the concavo-convex substrate facing the counter substrate, and an alignment film is formed on the surface of the counter substrate facing the concavo-convex substrate. Generation of alignment defects such as double domains can be suppressed, and uniform alignment of the ferroelectric liquid crystal can be obtained. If the surface of the concavo-convex substrate facing the counter substrate is subjected to an alignment process, the alignment process may negate the effect of the concavo-convex pattern, and the ferroelectric liquid crystal may not be uniformly aligned. is there.
Hereinafter, each structure of such an uneven substrate will be described.

(I) Concave and convex pattern In the liquid crystal display element of the present invention, ferroelectric liquid crystal is sandwiched between the concave and convex pattern and an alignment film described later. According to the present invention, it is considered that a good alignment state can be obtained by the interaction between the alignment regulating force due to the concavo-convex pattern and the ferroelectric liquid crystal, and the difference between the alignment regulating force due to the alignment film and the interaction between the ferroelectric liquid crystal. It is done.

  Such a concavo-convex pattern is not particularly limited as long as it can control the orientation of the ferroelectric liquid crystal when the ferroelectric liquid crystal is sandwiched between the concavo-convex pattern and the alignment film. 3 (a) and 3 (b) are preferably configured by the lattice-shaped or stripe-shaped convex portions 3. Moreover, when a convex part is a grid | lattice form, as a shape of a grid | lattice, a square or a rectangle may be sufficient.

  In this invention, it is preferable that the linear part of the said convex part cross | intersects the orientation direction of the alignment film mentioned later. Here, the straight portion of the convex portion means, for example, an arrow portion 31 as shown in FIGS. 3A and 3B, and the direction of the straight portion 31 is the alignment direction 32 of the alignment film. It is preferred that they intersect. The reason for this is not clear, but it is thought that the ferroelectric liquid crystal is sandwiched between different layers, such as the concavo-convex pattern and the alignment film, that is, the asymmetry of the upper and lower substrates contributes to the alignment control of the ferroelectric liquid crystal. It is done. In addition, the ferroelectric liquid crystal used in the present invention exhibits monostability, and has a property of having only one stable state when no voltage is applied, for example, as shown in FIG. In such a ferroelectric liquid crystal, two regions (double domains) having different layer normals are likely to be generated as shown in FIG. 7, but in the present invention, for example, as shown in FIG. It is considered that the occurrence of alignment defects such as double domains can be suppressed by crossing the three straight portions 31 with the alignment direction 32 of the alignment film. Note that the arrows 33 in FIGS. 3A and 3B indicate the layer normal 33 of the ferroelectric liquid crystal 34.

  The angle formed by the straight line portion of the convex portion and the alignment direction of the alignment film is not particularly limited as long as it intersects, but differs depending on the uneven pattern. When the concavo-convex pattern is constituted by stripe-shaped convex portions, as shown in FIG. 3A, the angle θ formed by the linear portion 31 of the stripe-shaped convex portions 3 and the alignment direction 32 of the alignment film is It is preferably in the range of 45 ° ± 25 °, more preferably in the range of 45 ° ± 10 °, particularly 45 °. This is because the orientation of the ferroelectric liquid crystal can be effectively controlled when the angle is in the above-described range. On the other hand, when the concavo-convex pattern is composed of lattice-shaped convex portions, as shown in FIG. 3B, the straight portions 31, 31 ′ of the lattice-shaped convex portions 3 and the alignment direction 32 of the alignment film Of the angles formed, the smaller angle θ is preferably about 30 ° to 45 °, more preferably within the range of 35 ° to 45 °, and particularly preferably 45 °. This is because the orientation of the ferroelectric liquid crystal can be effectively controlled when the angle is in the above-described range.

  The width of the convex portion of the concavo-convex pattern used in the present invention is usually about 0.1 μm to 2 μm, although it varies depending on the shape of the concavo-convex pattern. If the width of the convex portion is wider than the above range, the alignment of the ferroelectric liquid crystal may be abnormal in the concave and convex portion, causing light leakage in the dark state and possibly reducing the contrast. On the contrary, if the width of the convex portion is too small, it may be difficult to form the convex portion. Further, in order to suppress the alignment abnormality of ferroelectric liquid crystal and the decrease in contrast, the width of the convex portion is preferably as narrow as possible. Among the above, the range of 0.5 μm to 1.5 μm is preferable, and more preferable. Is in the range of 0.8 μm to 1.2 μm.

  Further, the pitch of the convex portions varies depending on the shape of the concavo-convex pattern, but is preferably about 5 μm to 500 μm, more preferably 10 μm to 200 μm, and particularly preferably within the range of 10 μm to 100 μm. If the pitch of the convex portion is narrower than the above range, the contrast may be lowered due to poor alignment of the ferroelectric liquid crystal near the convex portion. On the other hand, if the pitch of the convex portion is wider than the above range, the alignment by the concavo-convex pattern is possible. This is because it may be difficult to obtain the control effect.

  Furthermore, as a ratio of the width of the convex portion and the concave portion in the concave / convex pattern, the width of the concave portion is preferably wider than the width of the convex portion. Specifically, (the width of the convex portion) :( the width of the concave portion) is preferably 1: 5 to 1,000, more preferably 1:10 to 200, and particularly preferably 1:10 to 100. If the ratio of the width of the convex portion to the concave portion is too small, it becomes difficult to control the alignment of the ferroelectric liquid crystal, and if too large, the pitch of the convex portion is limited, so that it may be difficult to form the convex portion. Because.

  Note that the width of the convex portion indicates a width 21 as shown in FIG. 4, the width of the concave portion indicates a width 24, and the pitch of the convex portion indicates a pitch 22 as shown in FIG. It is shown. The widths of the convex portions and concave portions, and the pitch of the convex portions are values observed and measured using a non-contact atomic force microscope.

  The reason why it is preferable that the concave / convex pattern used in the present invention is a predetermined pattern as described above is not clear, but for example, when alignment films are formed on both upper and lower substrates, each alignment film and ferroelectric liquid crystal In the present invention, an alignment film is formed only on one substrate (counter substrate), and the upper and lower substrates are made asymmetric. Thus, it is considered that the monodomain alignment can be obtained and the layered structure of the ferroelectric liquid crystal can be stably held by the predetermined uneven pattern formed on the other substrate (uneven substrate). Therefore, in the present invention, it is considered that the alignment regulating force by the concavo-convex pattern is controlled by making the concavo-convex pattern a predetermined pattern, and as a result, the alignment of the ferroelectric liquid crystal is controlled.

  Furthermore, the height of the convex portion of the concavo-convex pattern is not particularly limited as long as it is smaller than the thickness of the liquid crystal layer to be described later and is a height that does not hinder the alignment control of the ferroelectric liquid crystal. The thickness is preferably about 50 nm to 1000 nm, and more preferably in the range of 100 nm to 500 nm.

  Here, the height of the convex portion being smaller than the thickness of the liquid crystal layer means that the convex portion 3 on the electrode layer 2d does not reach the alignment film 4 as shown in FIG. Specifically, the height of the convex portion is preferably 0.05 to 0.8, more preferably 0.1 to 0.3, with respect to the thickness 1 of the liquid crystal layer.

  The height of the convex portion indicates a height 23 as shown in FIG. The height of the convex portion is a value measured by observing the cross section of the convex portion with an SEM.

  The cross-sectional shape of the concavo-convex pattern may be any shape as long as a predetermined pattern can be formed, and may be a rectangle or a triangle, but is preferably a rectangle.

  Moreover, as a formation position of a convex part, it should just be formed so that the orientation direction of an alignment film and the linear part of a convex part may cross | intersect as mentioned above, The positional relationship of a convex part and an electrode layer is especially limited. Not done. For example, as shown in FIG. 5 (a), the stripe-shaped convex portions 3 may be formed in the same direction as the directions of the x electrode 2a and the y electrode 2b, and as shown in FIG. 5 (b), the convex portions 3 may be formed in a direction different from the directions of the x electrode 2a and the y electrode 2b. As shown in FIG. 5A, when the convex portion 3 and the x electrode 2a and the y electrode 2b are formed in the same direction, the alignment direction of the alignment film is different from the directions of the x electrode and the y electrode. It is preferable that

  In FIG. 5A, the protrusions 3 are formed so as to coincide with the pitch of the y electrodes 2b. However, as described above, the present invention is not limited to such formation positions. The pitches of the convex portions and the electrode layers may be different.

  Further, for example, as shown in FIG. 5A, when the convex portion 3 is formed in the same direction as the matrix of the electrode layer (x electrode 2a, y electrode 2b), the ferroelectric liquid crystal has an alignment direction and a vertical direction. However, since the viewing angle in the oblique direction is narrow, it is preferable to perform optical compensation for widening the viewing angle. Specifically, the viewing angle can be improved by attaching a viewing angle compensation film to the outside of the liquid crystal cell or providing a layer for expanding the viewing angle inside the liquid crystal cell.

  Further, in the present invention, as shown in FIG. 1, for example, an x electrode 2a, a y electrode 2b, a TFT element 7, a pixel electrode 2c and the like are formed on the counter substrate 12 to form a TFT substrate, and the uneven substrate 11 has a common electrode 2d and the like. May be formed as a common electrode substrate, or although not shown, the counter substrate may be a common electrode substrate and the concavo-convex substrate may be a TFT substrate. That is, the uneven pattern may be formed on the TFT substrate side or may be formed on the common electrode substrate side. In the present invention, in particular, it is preferable that the concave / convex pattern is formed on the common electrode substrate side, and it is more preferable that it is formed between the first substrate and the common electrode. This is because such a configuration has no voltage drop and is advantageous.

  The material for forming such a concavo-convex pattern is not particularly limited as long as it can form a predetermined pattern as described above, but the material itself preferably has no orientation. As described above, in the present invention, it is considered that the alignment of the ferroelectric liquid crystal is controlled by controlling the alignment regulating force by the concavo-convex pattern. Therefore, when the concavo-convex pattern forming material has orientation This is because there is a possibility of adversely affecting the alignment control of the ferroelectric liquid crystal.

  A specific forming material is not particularly limited as long as it is a resin that can be generally used for a liquid crystal display element, but a curable resin is preferable. This is because the curable resin is cured, and thus the uneven pattern can be stably maintained. Examples of such a curable resin include an energy ray curable resin that is cured by irradiation with energy rays, and a thermosetting resin that is cured by heat. Among them, it is preferable to use an energy ray curable resin. . Examples of the energy beam curable resin include a UV curable resin that is cured by irradiation with ultraviolet rays, and an electron beam curable resin that is cured by irradiation with an electron beam. preferable. This is because the method of using ultraviolet rays as energy rays is an already established technique and can be easily applied to the present invention.

  Such a UV curable resin is not particularly limited as long as it is cured by irradiation with ultraviolet rays, but is a resin in which a polyfunctional monomer component and / or oligomer component and / or polymer component is cured by photopolymerization. It is preferable.

  Although it does not specifically limit as said polyfunctional monomer component, A polyfunctional acrylate monomer is used suitably. Specifically, ethylene glycol (meth) acrylate, diethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) Acrylate, hexane di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate, glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol diacrylate, penta Erythritol (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol Ruhekisa (meth) acrylate can be exemplified dipentaerythritol penta (meth) acrylate.

  The oligomer component is not particularly limited, and examples thereof include urethane acrylate, epoxy acrylate, polyester acrylate, epoxy, vinyl ether, and polyene / thiol.

  The polymer component is not particularly limited, and examples thereof include a photocrosslinking polymer. Specifically, a polyvinyl cinnamate-based resin that causes a photodimerization reaction can be used.

  Furthermore, you may add a photoinitiator to the said UV curable resin as needed. As such a photopolymerization initiator, a radical photopolymerization initiator that can be activated by ultraviolet light, for example, ultraviolet light of 365 nm or less is used. Specifically, benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamine) benzophenone, α-amino-acetophenone, 4,4-dichlorobenzophenone, 4- Benzoyl-4-methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, p-tert-butyldichloro Acetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyldimethyl ketal, benzylmethoxyethyl acetal, benzoin methyl ether, Nzoin butyl ether, anthraquinone, 2-tert-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzsuberon, methyleneanthrone, 4-azidobenzylacetophenone, 2,6-bis (p-azidobenzylidene ) Cyclohexane, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-methoxycarbonyl) oxime, 1-phenyl-propanedione-2- ( o-ethoxycarbonyl) oxime, 1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxime, Michler's ketone 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, naphthalenesulfonyl chloride, quinoline Sulfonyl chloride, n-phenylthioacridone, 4,4-azobisisobutyronitrile, diphenyl disulfide, benzthiazole disulfide, triphenylphosphine, camphorquinone, Adeka N1717, carbon tetrabromide, tribromophenyl sulfone, Examples thereof include a combination of a photoreductive dye such as benzoin peroxide, eosin and methylene blue with a reducing agent such as ascorbic acid or triethanolamine. In this invention, these photoinitiators can be used 1 type or in combination of 2 or more types.

  The content of such a photopolymerization initiator is preferably in the range of 0.5 to 30% by weight, particularly in the range of 1 to 10% by weight, in the UV curable resin.

  The method for forming the concavo-convex pattern is not particularly limited as long as a predetermined pattern can be formed, and a general patterning method can be used. For example, it can be performed by a photolithography method, an inkjet method, a screen printing method, a 2P method (Photo polymerization method), or the like. Among these, the 2P method (Photo polymerization method) can be preferably used in the present invention.

  Hereinafter, a method for forming a concavo-convex pattern using the 2P method will be described. First, a curable resin is applied on a transfer member having a concavo-convex pattern, and a surface facing the liquid crystal layer of the first substrate provided with the electrode layer is brought into contact with the curable resin. At this time, a curable resin may be applied to the surface of the first substrate provided with the electrode layer facing the liquid crystal layer, and a transfer member having an uneven pattern may be brought into contact with the curable resin. Next, the concavo-convex pattern made of the curable resin can be transferred by irradiating the curable resin with energy to cure and peeling the transfer member.

  When applying the curable resin, the curable resin may be diluted with a solvent. Examples of usable solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, ethylene glycol and propylene glycol; terpenes such as α- and β-terpineol; acetone, methyl ethyl ketone, cyclohexanone and N-methyl-2. -Ketones such as pyrrolidone; aromatic hydrocarbons such as toluene, xylene, tetramethylbenzene; cellosolve, methyl cellosolve, ethyl cellosolve, carbitol, methyl carbitol, ethyl carbitol, butyl carbitol, propylene glycol monomethyl ether, Propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether Glycol ethers such as triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, carbitol acetate, ethyl carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, propylene Acetic acid esters such as glycol monoethyl ether acetate can be exemplified. Moreover, 1 type (s) or 2 or more types can be mixed and used from these solvents.

  As the content of such a solvent, since it may be applied without adding a solvent to the curable resin, it is in the range of 0 to 99.9% by weight in the curable resin, particularly 0 to 80% by weight. It is preferable to be within the range.

  Examples of the coating method include spin coating, roll coating, printing, dip coating, curtain coating (die coating), and the like.

  Examples of the method of curing the curable resin include a method of irradiating energy rays, a method of heating, and the like. In the present invention, a method of irradiating energy rays is preferable. The energy ray as used in the present invention means an energy ray capable of causing polymerization with respect to the monomer and polymer contained in the curable resin, and if necessary, a polymerization initiator is contained in the curable resin as described above. It may be included.

  Such an energy ray is not particularly limited as long as it is an energy ray capable of polymerizing a curable resin, but usually ultraviolet light or visible light is used from the viewpoint of the ease of equipment and the like. Irradiation light having a wavelength of 150 to 500 nm, preferably 250 to 450, and more preferably 300 to 400 nm is used. Of these, the method of irradiating ultraviolet rays (UV) as energy rays is a preferable method. This is because the method using UV as the actinic radiation is an already established technique, and therefore it is easy to apply to the present invention including the photopolymerization initiator to be used.

  As the light source of this irradiation light, low pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), high pressure discharge lamp (high pressure mercury lamp, metal halide lamp), short arc discharge lamp (super high pressure mercury lamp, xenon lamp, mercury xenon) Lamp). Among these, use of a metal halide lamp, a xenon lamp, a high-pressure mercury lamp, etc. is recommended. The irradiation intensity is appropriately adjusted depending on the composition of the curable resin and the amount of the polymerization initiator.

(Ii) First substrate Next, the first substrate used in the present invention will be described. The 1st board | substrate used for this invention will not be specifically limited if generally used as a board | substrate of a liquid crystal display element, For example, a glass plate, a plastic plate, etc. are mentioned preferably. The surface roughness (RSM value) of the first substrate is preferably 10 nm or less, more preferably 3 nm or less, and still more preferably 1 nm or less. The surface roughness is a value measured using an atomic force microscope (AFM).

(Iii) Electrode layer Next, the electrode layer used in the present invention will be described. The electrode layer used in the present invention is not particularly limited as long as it is generally used as an electrode of a liquid crystal display element, but at least one is preferably formed of a transparent conductor. Preferred examples of the transparent conductor material include indium oxide, tin oxide, indium tin oxide (ITO), and the like. When the liquid crystal display element of the present invention is an active matrix type liquid crystal display element using TFTs, one of the electrode layers of the concavo-convex substrate and the counter substrate is an entire surface common electrode formed of the transparent conductor. On the other hand, an x electrode and a y electrode are arranged in a matrix, and a TFT element and a pixel electrode are arranged in a portion surrounded by the x electrode and the y electrode. In this case, the step of the electrode layer formed by the pixel electrode, TFT element, x electrode, and y electrode is preferably 0.2 μm or less. This is because if the step is too large, the alignment of the ferroelectric liquid crystal may be disturbed.

  As the electrode layer, a transparent conductive film can be formed on the first substrate by a vapor deposition method such as a CVD method, a sputtering method, or an ion plating method, and the x electrode and the y electrode are formed by patterning this in a matrix shape. Can be formed.

(2) Counter substrate Next, the counter substrate used in the present invention will be described. The counter substrate used in the present invention has a second substrate, an electrode layer formed on the second substrate, and an alignment film formed on the electrode layer. Hereinafter, each configuration of the counter substrate will be described. The second substrate is the same as that described in the column of the first substrate of the concavo-convex substrate, and the electrode layer is the same as that described in the column of the electrode layer of the concavo-convex substrate. Description is omitted.

(I) Alignment film The alignment film used in the present invention is not particularly limited as long as the liquid crystal can be aligned. For example, a film subjected to rubbing treatment, photo-alignment treatment, or the like is used. it can. Among these, in the present invention, a photo-alignment film subjected to photo-alignment treatment is preferable. This is because the photo-alignment process is a non-contact alignment process, which is useful in that it does not generate static electricity or dust and can quantitatively control the alignment process. Hereinafter, such a photo-alignment film will be described.

(Photo-alignment film)
The photo-alignment film is anisotropic to the film obtained by irradiating the substrate coated with the constituent material of the photo-alignment film, which will be described later, with light whose polarization is controlled to cause a photoexcitation reaction (decomposition, isomerization, dimerization). Is used to align the liquid crystal molecules on the film.

  The constituent material of the photo-alignment film used in the present invention is particularly limited as long as it has the effect of aligning the ferroelectric liquid crystal (photo-alignment) by irradiating light and causing a photoexcitation reaction. However, such materials can be broadly divided into photoisomerization types in which only the molecular shape changes and reversible orientation changes are possible, and photoreaction types in which the molecules themselves change.

  Here, the photoisomerization reaction refers to a phenomenon in which a single compound changes to another isomer by light irradiation. By using such a photoisomerizable material, a stable isomer among a plurality of isomers is increased by light irradiation, whereby anisotropy can be easily imparted to the photo-alignment film.

  In addition, the photoreaction is not limited as long as the molecule itself is changed by light irradiation and anisotropy can be imparted to the photoalignment property of the photoalignment film, but anisotropy is imparted to the photoalignment film. Is easier, it is preferably a photodimerization reaction or a photolysis reaction. Here, the photodimerization reaction refers to a reaction in which two reaction molecules oriented in the polarization direction by light irradiation undergo radical polymerization and two molecules are polymerized. By this reaction, the alignment in the polarization direction can be stabilized and anisotropy can be imparted to the photo-alignment film. On the other hand, the photolysis reaction refers to a reaction that decomposes molecular chains such as polyimide oriented in the polarization direction by light irradiation. This reaction leaves molecular chains aligned in the direction perpendicular to the polarization direction, and can provide anisotropy to the photo-alignment film.

  In the present invention, as a constituent material of the photo-alignment film, among the above, a photo-reactive material that imparts anisotropy to the photo-alignment film by causing a photodimerization reaction, or a photo-isomerization reaction It is preferable to use a photoisomerizable material that imparts anisotropy to the photo-alignment film. Furthermore, since the exposure sensitivity is high and the range of material selection is wide, it is more preferable to use a material that imparts anisotropy to the photo-alignment film by a photodimerization reaction.

  The wavelength region of the light that causes the photoexcitation reaction of the constituent material of the photo-alignment film is preferably in the ultraviolet light range, that is, in the range of 10 nm to 400 nm, and more preferably in the range of 250 nm to 380 nm. .

  The photoisomerization type material is not particularly limited as long as it is a material that can impart anisotropy to the photoalignment film by a photoisomerization reaction, but dichroism that makes absorption different depending on the polarization direction. It is preferable to include a photoisomerization reactive compound that has an isomerization reaction upon irradiation with light. Anisotropy can be easily imparted to the photo-alignment film by causing isomerization of the reaction site oriented in the polarization direction of the photoisomerization-reactive compound having such characteristics.

  In the photoisomerization reactive compound, the isomerization reaction is preferably a cis-trans isomerization reaction. This is because either the cis isomer or the trans isomer is increased by light irradiation, whereby anisotropy can be imparted to the photo-alignment film.

  Examples of the photoisomerization-reactive compound used in the present invention include a monomolecular compound or a polymerizable monomer that is polymerized by light or heat. These may be appropriately selected according to the type of the ferroelectric liquid crystal to be used. However, the anisotropy is imparted to the photo-alignment film by light irradiation and then polymerized to stabilize the anisotropy. Therefore, it is preferable to use a polymerizable monomer. Among such polymerizable monomers, after anisotropy is imparted to the photo-alignment film, it can be easily polymerized while maintaining the anisotropy in a good state, so that it is an acrylate monomer or a methacrylate monomer. preferable.

  Specific examples of such a photoisomerization-reactive compound include compounds having a cis-trans isomerization-reactive skeleton such as an azobenzene skeleton or a stilbene skeleton.

  Among the photomolecular isomerization reactive compounds of the monomolecular compound or polymerizable monomer as described above, the photoisomerization reactive compound used in the present invention is preferably a compound having an azobenzene skeleton in the molecule. This is because the azobenzene skeleton contains a lot of π electrons, and thus has a high interaction with liquid crystal molecules and is particularly suitable for controlling the alignment of ferroelectric liquid crystals.

  In addition, the photoreactive material utilizing the photodimerization reaction is not particularly limited as long as it is a material that can impart anisotropy to the photoalignment film by the photodimerization reaction, but it is a radical polymerizable material. It is preferable to include a photodimerization reactive compound having a dichroism having a functional group and different absorption depending on the polarization direction. This is because by radical polymerization of the reaction site oriented in the polarization direction, the orientation of the photodimerization reactive compound is stabilized and anisotropy can be easily imparted to the photo-alignment film.

  Examples of the photodimerization reactive compound having such characteristics include a dimerization reactive polymer having at least one reactive site selected from cinnamate ester, coumarin, quinoline, chalcone group and cinnamoyl group as a side chain. Can do. Among these, the photodimerization reactive compound is preferably a dimerization reactive polymer containing any one of cinnamate ester, coumarin and quinoline as a side chain. This is because anisotropy can be easily imparted to the photo-alignment film by radical polymerization of α and β unsaturated ketone double bonds aligned in the polarization direction as reaction sites.

  The main chain of the dimerization reactive polymer is not particularly limited as long as it is generally known as a polymer main chain, but the reaction sites of the side chains such as aromatic hydrocarbon groups are not limited. It is preferable that it does not have a substituent containing a lot of π electrons that hinders the interaction.

  Moreover, the constituent material of the photo-alignment film used in the present invention may contain an additive as long as the optical alignment property of the photo-alignment film is not hindered. Examples of the additive include a polymerization initiator and a polymerization inhibitor.

  Next, the photo-alignment processing method will be described. First, a coating solution obtained by diluting the constituent material of the above-described photo-alignment film with an organic solvent is applied to the surface of the second substrate provided with the electrode layer facing the liquid crystal layer, and dried. In this case, the content of the photodimerization reactive compound or the photoisomerization reactive compound in the coating liquid is preferably in the range of 0.05% by weight to 10% by weight, More preferably, it is in the range of 2% by weight. If the content is smaller than the above range, it will be difficult to impart an appropriate anisotropy to the alignment film. Conversely, if the content is larger than the above range, the viscosity of the coating liquid will increase, so a uniform coating film will be formed. It is because it becomes difficult to form.

  As a coating method, a spin coating method, a roll coating method, a rod bar coating method, a spray coating method, an air knife coating method, a slot die coating method, a wire bar coating method, or the like can be used.

  The thickness of the film obtained by applying the above constituent materials is preferably in the range of 1 nm to 1000 nm, more preferably in the range of 3 nm to 100 nm. This is because if the thickness of the film is thinner than the above range, sufficient optical alignment may not be obtained, and conversely, if the thickness is thicker than the above range, it may be disadvantageous in cost.

  The obtained film can impart anisotropy by causing a photoexcitation reaction by irradiating light with polarization controlled. The wavelength range of the light to be irradiated may be appropriately selected according to the constituent material of the photo-alignment film to be used, but is preferably in the ultraviolet light range, that is, in the range of 100 nm to 400 nm, more preferably 250 nm. Within the range of ˜380 nm.

  The photo-alignment treatment of the film can also be performed by irradiating non-polarized ultraviolet rays obliquely. The light irradiation direction is not particularly limited as long as it can cause the above-described photoexcitation reaction. However, since the alignment state of the ferroelectric liquid crystal can be improved, the upper and lower photo-alignment films Both are preferably in the range of 10 ° to 45 ° oblique to the substrate surface, more preferably in the range of 30 ° to 45 °.

  Furthermore, when a polymerizable monomer is used as a constituent material of the photo-alignment film, among the above photoisomerization-reactive compounds, after photo-alignment treatment, it is polymerized by heating to form a photo-alignment film. The provided anisotropy can be stabilized.

  As described above, the orientation direction of the photo-alignment film after the photo-alignment treatment is preferably intersected with the straight portion of the convex portion, and may form a predetermined angle with the linear portion of the convex portion. preferable. This is because the alignment of the ferroelectric liquid crystal can be controlled effectively.

(3) Liquid Crystal Layer Next, the liquid crystal layer used in the present invention will be described. The liquid crystal layer used in the present invention is configured by sandwiching a ferroelectric liquid crystal with the concavo-convex pattern and the photo-alignment film. The ferroelectric liquid crystal used in the liquid crystal layer is not particularly limited as long as it exhibits a chiral smectic C phase (SmC ^* ) and exhibits monostability, but the phase sequence of the ferroelectric liquid crystal is Phase change with nematic phase (N) -cholesteric phase (Ch) -chiral smectic C phase (SmC ^* ), or nematic phase (N) -chiral smectic C phase (SmC ^* ), not via smectic A phase (SmA) A material is preferred. Such a liquid crystal material having monostability that does not pass through the smectic A phase is suitably used when the liquid crystal display element of the present invention is driven by a field sequential color system. Here, monostable refers to the property of having only one stable state when no voltage is applied as described above, and in particular, half V-shaped driving in which liquid crystal molecules operate only when either positive or negative voltage is applied. This is preferable in that the opening time of the black-and-white shutter can be increased and a bright color display can be realized.

  Further, in the present invention, by using such a monostable liquid crystal material that does not pass through the smectic A phase, driving by an active matrix method using a thin film transistor (TFT) is possible, and voltage modulation is performed. Thus, gradation control is possible, and high-definition and high-quality display can be realized.

  The liquid crystal display element of the present invention can perform color display by arranging a micro color filter on the TFT substrate side or the common electrode substrate side. However, by utilizing the high-speed response of the ferroelectric liquid crystal, the micro color filter can be used. Without using a filter, color display by a field sequential color system is possible in combination with an LED light source.

  Furthermore, since the ferroelectric liquid crystal exhibits monostability, the liquid crystal display element of the present invention is basically driven by an active matrix method using TFT, but can also be driven by a segment method. is there.

  The ferroelectric liquid crystal used in the present invention preferably constitutes a single phase. Here, constituting a single phase means that a polymer network is not formed as in a polymer stabilization method or a polymer stabilization method. Thus, by using a single-phase ferroelectric liquid crystal, there are advantages that the manufacturing process becomes easy and the drive voltage can be lowered.

  The thickness of the liquid crystal layer composed of the ferroelectric liquid crystal is preferably in the range of 1.2 μm to 3.0 μm, more preferably 1.3 μm to 2.5 μm, still more preferably 1.4 μm to 2 μm. Within the range of 0.0 μm.

  As a method for forming the liquid crystal layer, a method generally used as a method for manufacturing a liquid crystal cell can be used. For example, an isotropic liquid is formed by heating the ferroelectric liquid crystal in a liquid crystal cell in which a concavo-convex substrate and a counter substrate are prepared in advance, and the liquid crystal layer is injected by using the capillary effect and sealed with an adhesive. Can be formed. The thickness of the liquid crystal layer can be adjusted by a spacer such as beads.

(4) Polarizing plate Next, the polarizing plate used for this invention is demonstrated. The polarizing plate used in the present invention is not particularly limited as long as it transmits only a specific direction in the wave of light, and those generally used as a polarizing plate of a liquid crystal display element can be used. .

2. Next, a method for manufacturing a liquid crystal display element of the present invention will be described. The liquid crystal display element of this invention can be manufactured by the method generally used as a manufacturing method of a liquid crystal display element. Hereinafter, as an example of a method for manufacturing a liquid crystal display element of the present invention, a method for manufacturing an active matrix liquid crystal display element using TFT elements will be described.

  First, a transparent conductive film is formed on the first substrate by the vapor deposition method described above to form a common electrode on the entire surface. Furthermore, a concavo-convex pattern is formed on the common electrode by the patterning method described above to obtain a concavo-convex substrate. On the second substrate, an x electrode and a y electrode are formed by patterning a transparent conductive film on a matrix, and a switching element and a pixel electrode are provided. Furthermore, a photo-alignment film material is applied on the x electrode, the y electrode, the switching element, and the pixel electrode, and a photo-alignment process is performed to form a photo-alignment film, thereby forming a counter substrate. Beads are dispersed as spacers on the photo-alignment film of the counter substrate formed in this way, and a sealing agent is applied to the periphery so that the concavo-convex pattern of the concavo-convex substrate and the photo-alignment film of the counter substrate are bonded to each other, It is thermocompression bonded. Then, the ferroelectric liquid crystal is injected in an isotropic liquid state using the capillary effect from the injection port, and the injection port is sealed with an ultraviolet curable resin or the like. Thereafter, the ferroelectric liquid crystal can be aligned by slow cooling. Thus, the liquid crystal display element of this invention can be obtained by sticking a polarizing plate on the upper and lower sides of the obtained liquid crystal cell.

3. Next, the use of the liquid crystal display element of the present invention will be described. The liquid crystal display element of the present invention is preferably driven by a field sequential color system. As described above, the field sequential color system divides one pixel in time, and requires high-speed response in order to obtain good moving image display characteristics. In this respect, the liquid crystal display element of the present invention uses a ferroelectric liquid crystal, and has a high response speed and a wide viewing angle, so that the moving image display characteristics are excellent, and it is driven by a field sequential color system to achieve high definition. This is because an accurate color display is possible.

  In this case, as the ferroelectric liquid crystal, it is preferable to use a material having monostability that expresses a chiral smectic C phase from the cholesteric phase without passing through the smectic A phase. Such a material exhibits electro-optic characteristics in which the inclination of the major axis of liquid crystal molecules is the same when a positive voltage is applied and when a negative voltage is applied, and the light transmittance with respect to the applied voltage is asymmetric. This characteristic is referred to herein as half-V shaped switching (HV-shaped switching). By using a material exhibiting such HV-shaped switching characteristics, the opening time as a black and white shutter can be made sufficiently long. Accordingly, each color that can be switched over time can be displayed brighter, and a bright color liquid crystal display element can be realized.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be specifically described with reference to examples.

[Example 1]
(Production of uneven substrate)
A 0.1% silane coupling agent ethanol solution was applied to the cleaned glass substrate with electrodes using a spinner and dried to form an anchor layer having a thickness of 10 nm. On this anchor layer, a UV curable monomer is applied, a polycarbonate original plate having a desired concavo-convex pattern formed thereon is pressed and cured at a pressure of 5 kg / cm ² while being irradiated with ultraviolet rays of about 100 mJ / cm ^2. After peeling off the original plate, it was further cured by irradiating with 1000 mJ / cm ² of ultraviolet rays to form a concavo-convex pattern. Thereby, an uneven substrate was obtained. This concavo-convex pattern had a lattice shape with a convex portion width: 0.2 μm, a pitch: 20 μm, and a height: 400 nm.

(Preparation of counter substrate)
A 2% cyclopentanone solution containing a photodimerization reactive compound having a cinnamate group in the side chain was applied to a cleaned glass substrate with an electrode using a spinner and dried to form a photo-alignment film of about 80 nm. . This photo-alignment film was irradiated with polarized ultraviolet rays, and subjected to an alignment treatment so as to be in a direction of 45 ° with the direction of the linear portion of the lattice-like uneven pattern of the uneven substrate. Thereby, a counter substrate was obtained.

(Evaluation)
A 1.5 μm spacer sphere was sprayed on the uneven substrate side, a sealant was applied to the counter substrate side, and these substrates were bonded to face each other, thereby preparing a test cell. A ferroelectric liquid crystal (trade name: R2301 manufactured by Clariant Japan Co., Ltd.) was injected into this cell at an isotropic phase temperature, and after slow cooling to room temperature, the alignment state was observed. Got. Further, when the voltage-transmittance characteristics of the test cell were measured, HV driving characteristics were shown.

[Example 2]
(Production of uneven substrate)
A concavo-convex substrate was produced in the same manner as in Example 1. The concavo-convex pattern of the concavo-convex substrate was a stripe shape having a convex portion width of 1 μm, a pitch of 20 μm, and a height of 400 nm.

(Preparation of counter substrate)
A photo-alignment film is formed in the same manner as in Example 1, and this photo-alignment film is irradiated with polarized ultraviolet rays so that the alignment process is performed so that the direction of the linear portion of the stripe-like uneven pattern of the uneven substrate is 45 °. Was given. Thereby, a counter substrate was obtained.

(Evaluation)
A test cell was produced in the same manner as in Example 1, and ferroelectric liquid crystal was injected into this cell. Furthermore, after cooling slowly to room temperature, when the orientation state was observed, the uniform orientation of the monodomain was obtained.

[Comparative Example 1]
(Production of uneven substrate)
A concavo-convex substrate was produced in the same manner as in Example 1.

(Preparation of counter substrate)
A photo-alignment film was formed in the same manner as in Example 1, and this photo-alignment film was irradiated with polarized ultraviolet rays, and subjected to an alignment process so that it was in the same direction as the direction of the linear portion of the lattice-like concavo-convex pattern of the concavo-convex substrate. did. Thereby, a counter substrate was obtained.

(Evaluation)
A test cell was produced in the same manner as in Example 1, and ferroelectric liquid crystal was injected into this cell. Furthermore, after slow cooling to room temperature, the orientation state was observed, and double domains were observed.

[Comparative Example 2]
(Production of uneven substrate)
A concavo-convex substrate was produced in the same manner as in Example 2.

(Preparation of counter substrate)
A photo-alignment film is formed in the same manner as in Example 1, and this photo-alignment film is irradiated with polarized ultraviolet light, and an alignment process is performed so that the direction is the same as the direction of the linear portion of the striped uneven pattern of the uneven substrate. did. Thereby, a counter substrate was obtained.

(Evaluation)
A test cell was produced in the same manner as in Example 1, and ferroelectric liquid crystal was injected into this cell. Furthermore, after slow cooling to room temperature, the orientation state was observed, and double domains were observed.

[Comparative Example 3]
(Production of uneven substrate)
A concavo-convex substrate was produced in the same manner as in Example 1, and a coating solution containing a photodimerization reactive compound having a cinnamate group in the side chain was spin-coated on the concavo-convex pattern, and the film thickness was about 80 nm. The photo-alignment film was laminated. This photo-alignment film was subjected to polarized ultraviolet light exposure and subjected to an alignment treatment so as to be in the same direction as the linear portion of the lattice-like uneven pattern of the uneven substrate. Thereby, an uneven substrate was obtained.

(Preparation of counter substrate)
A photo-alignment film was formed in the same manner as in Example 1, and this photo-alignment film was irradiated with polarized ultraviolet rays, and subjected to an alignment process so that it was in the same direction as the direction of the linear portion of the lattice-like concavo-convex pattern of the concavo-convex substrate. did. Thereby, a counter substrate was obtained.

(Evaluation)
A test cell was produced in the same manner as in Example 1, and ferroelectric liquid crystal was injected into this cell. Furthermore, after slow cooling to room temperature, the orientation state was observed, and double domains were observed.

[Examples 3 and 4]
Test cell in the same manner as in Example 1 except that the angle formed by the direction of the straight line portion of the concavo-convex pattern of the concavo-convex substrate and the alignment treatment direction of the photo-alignment film of the counter substrate was 40 ° or 30 °. Was made. When ferroelectric liquid crystal was injected into this cell and slowly cooled to room temperature, the alignment state was observed. The results shown in Table 1 below were obtained.

[Comparative Examples 4 to 6]
Except that the angle formed by the direction of the straight line portion of the lattice-shaped uneven pattern of the uneven substrate and the alignment treatment direction of the photo-alignment film of the counter substrate was 20 °, 10 ° or 5 °, the same as in Example 1 A test cell was prepared. When ferroelectric liquid crystal was injected into this cell and slowly cooled to room temperature, the alignment state was observed. The results shown in Table 1 below were obtained.

It is a schematic perspective view which shows an example of the liquid crystal display element of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display element of this invention. It is explanatory drawing for demonstrating the positional relationship of the uneven | corrugated pattern and the orientation direction of an alignment film in the liquid crystal display element of this invention. It is explanatory drawing for demonstrating an uneven | corrugated pattern. It is explanatory drawing for demonstrating the positional relationship of the uneven | corrugated pattern and electrode layer in the liquid crystal display element of this invention. It is the graph which showed the change of the transmittance | permeability with respect to the applied voltage of a ferroelectric liquid crystal. It is the figure which showed the difference in the orientation defect by the difference in the phase sequence which a ferroelectric liquid crystal has. It is the photograph which showed the double domain which is the orientation defect of a ferroelectric liquid crystal. It is explanatory drawing for demonstrating the conventional liquid crystal display element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a ... 1st board | substrate 1b ... 2nd board | substrate 2a, 2b, 2c, 2d ... Electrode layer 3 ... Uneven | corrugated pattern 4 ... Orientation film 5 ... Liquid crystal layer 6a, 6b ... Polarizing plate 11 ... Uneven substrate 12 ... Opposite substrate

Claims (9)

  A concavo-convex substrate having a first substrate, an electrode layer and a concavo-convex pattern formed on the first substrate, a second substrate, an electrode layer formed on the second substrate, and the electrode layer A counter substrate having an alignment film formed and having an alignment ability is disposed so that the concave / convex pattern of the concave / convex substrate and the alignment film of the counter substrate face each other, and monostability is provided between the concave / convex substrate and the counter substrate. A liquid crystal display element characterized by sandwiching a ferroelectric liquid crystal exhibiting the above.   The liquid crystal display element according to claim 1, wherein the concavo-convex pattern is configured by lattice-shaped or stripe-shaped convex portions.   The grid-like or stripe-like convex part is formed so that a linear portion of the grid-like or stripe-like convex part intersects the alignment direction of the alignment film. Liquid crystal display element.   4. The liquid crystal according to claim 3, wherein the smaller one of the angles formed by the linear portions of the lattice-shaped convex portions and the alignment direction of the alignment film is within a range of 30 ° to 45 °. Display element.   5. The liquid crystal display element according to claim 1, wherein an electrode layer or an uneven pattern of the uneven substrate is in direct contact with the ferroelectric liquid crystal.   The liquid crystal display element according to claim 1, wherein the ferroelectric liquid crystal does not have a smectic A phase in a phase series.   The liquid crystal display element according to claim 1, wherein the alignment film is a photo-alignment film.   The height of the said convex part is smaller than the thickness of the liquid-crystal layer comprised by the said ferroelectric liquid crystal being clamped, The claim from any one of Claim 2 to 7 characterized by the above-mentioned. Liquid crystal display element. The liquid crystal display element according to any one of claims 1 to 8, wherein the liquid crystal display element is driven by a field sequential color system.

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