JP2008242030A - Manufacturing method of liquid crystal panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a liquid crystal panel with less variation in alignment direction when manufacturing the liquid crystal panel using an inorganic vapor-deposited film represented by an SiO obliquely vapor-deposited film as an alignment film. <P>SOLUTION: The manufacturing method includes: a vapor-deposition step of preparing a plurality of large-sized substrates 31a and 31b having a plurality of cell substrates and subjecting the plurality of large-sized substrates 31a and 31b to vapor deposition; a large-sized substrate division step of obtaining a plurality of divided substrates by dividing the large-sized substrates 31a and 31b along a vapor position center line by which a direction of projection of a vapor deposition beam for vapor deposition of the large-sized substrates into the large-sized substrates is parallel with end sides of the large-sized substrates, or a line parallel with it; and a sticking step of selecting two divided substrates disposed in positions in the same direction from a vapor deposition source 23 with respect to the vapor deposition center line, from among two different large-sized substrates and sticking the two divided substrates to each other as a pair of divided substrates so that their vapor-deposited surfaces face each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid crystal panel having a variation in alignment direction in a method for manufacturing a liquid crystal panel having an inorganic vapor deposition film as an alignment film.

  As one of liquid crystal alignment methods, an alignment method using an inorganic vapor deposition film has been studied for a long time. In particular, in recent years, in liquid crystal panels that handle a large amount of light as typified by projectors and the like, an application using an alignment method using an inorganic vapor deposition film is increasing due to a demand from light resistance. In addition, in the alignment method of ferroelectric liquid crystals characterized by high-speed response and memory characteristics, it is known that horizontal alignment with an inorganic vapor deposition film is effective for achieving more stable memory performance. ing.

  FIG. 2 is a view showing a panel combining a general oblique deposition method using SiO or SiO2 and a deposition substrate. A ferroelectric liquid crystal exhibiting bistability is injected into the panel and is horizontally aligned.

  As shown in FIG. 2 (c), a substrate including necessary elements such as a transparent electrode is deposited at a deposition angle 25 (a: 80-87) with respect to the deposition source 23 (inorganic oxide such as SiO) under vacuum conditions. Vapor deposition is performed. FIG. 2A is a cross-sectional view of a liquid crystal panel in which a pair of substrates (21a, 21b) thus deposited are combined so as to be parallel to each other. The liquid crystal panel is configured through a spacer (not shown) in the same manner as a general liquid crystal panel manufacturing method. FIG. 2B is a plan view of the liquid crystal panel. Each of the combined upper and lower substrates (21a, 21b) is bonded so that the vapor deposition direction (26) is parallel. When a ferroelectric liquid crystal having a phase series of IACC is injected into such a liquid crystal panel, the ferroelectric liquid crystal has a layer normal (27) along the deposition direction (26) as shown in FIG. 1 (b). It is known that the orientation is as follows.

  The liquid crystal molecules (29) of the ferroelectric liquid crystal move around the conical surface having a cone angle θ, but when the cell gap is thin, the liquid crystal molecules become a surface stable ferroelectric liquid crystal (SSFLC), which is shown in FIG. As shown in the figure, the liquid crystal molecules (29) settle in one of two stable states (28a, 28b) when no electric field is applied (memory state). When an electric field is applied, any stable state can be selected depending on the polarity of the electric field (for example, Patent Document 1).

  Next, a pair of polarizing plates is arranged outside the pair of substrates (21a, 21b) so that the polarization axes thereof are orthogonal to each other. As shown in the front view of FIG. 2B, the polarization axis of one of the pair of polarizing plates is aligned with one of the two stable states (28a, 28b) of the liquid crystal molecule (29), and the liquid crystal molecule (29 ) To be parallel to the long axis. In the case of FIG. 2, the polarization axis (P) of one polarizing plate is aligned with the position of stable state 1 (28a), and the polarization axis (A) of the other polarizing plate is orthogonal to the polarization axis (P). Deploy.

With such an arrangement, a display function is realized by the birefringence of the ferroelectric liquid crystal. That is, in the front view of FIG. 2B, by applying an electric field having a specific polarity and bringing the liquid crystal molecules into the stable state 1 (28a), the optical axis coincides with the polarization axis, and the light can be blocked. it can. This corresponds to the black display on the liquid crystal display. On the other hand, when an electric field opposite to the polarity is applied, the liquid crystal molecules (29) move to the stable state 2 (28b), the optical axis deviates from the polarization axis, and light leaks. This state corresponds to the bright state of the display. In this case, the transmittance is expressed by the following formula 1.
Formula 1: T = sin ² (4q) sin ² (pDnd / l)
(T: transmittance, q: tilt angle, Dn: anisotropy of refractive index of liquid crystal, d: thickness of liquid crystal layer, l: wavelength)

JP-A-5-281580 (2nd page, FIG. 2)

  However, the present inventor has found through experimentation that when producing a liquid crystal element using an inorganic vapor deposition film as an alignment film, there is a variation in contrast caused by a prospective angle derived from the width of the substrate during vapor deposition. Hereinafter, description will be made with reference to FIGS. 3 and 4.

  FIG. 3 is a diagram showing a substrate arrangement during vapor deposition generally performed so far and a liquid crystal cell constituted thereby. In order to increase production efficiency, large substrates are generally sized so that a certain number of liquid crystal cells can be produced together. For convenience, FIG. 3 shows a configuration in which 24 cell substrates can be taken from one large substrate 31, but in principle, any number of substrates can be obtained. The vapor deposition center line is a line in which the projection direction of the vapor deposition beam deposited on the large substrate 31 from the vapor deposition source 23 is parallel to the edge of the large substrate. FIG. 4 is an enlarged view of two cell substrates at positions on both sides of the deposition center line, FIG. 3A shows the cell substrate A1 and the cell substrate A2, and FIG. 3B shows the cell substrate B1 and the cell substrate B2. It is.

  As shown in FIG. 4, since the large substrate 31 has a certain width with respect to the vapor deposition source 23, there is a certain prospective angle Φ with respect to the vapor deposition source. For this reason, on the surface of the large-sized board | substrate which vapor-deposited, the actual vapor deposition direction has distribution rather than one direction depending on a place. That is, in the positions of arrows A and B immediately above the deposition source in FIG. 4, the deposition direction is along the substrate edge as expected, but as it is further away, the deviation gradually increases, In the arrows A− and B−, the deposition direction is shifted by an angle −Φ corresponding to the width of the substrate, and by the angle + Φ in the arrows A + and B + at the edge. The cell substrates A1 and A2 of the large substrate 31 deposited in FIG. 3 (a) and the surfaces of the large substrate 31 deposited in FIG. 3 (b) on which the cell substrate B1 and the cell substrate B2 are directly deposited face each other. As shown in the upper part of FIG. 4, the arrows overlap like the panel A1B2 (32a) and the panel A2B1 (32b) as shown in the upper part of FIG. Reflected as it is, the liquid crystal alignment direction after injecting the liquid crystal accordingly has a similar distribution.

  When the pair of substrates thus obtained is divided into individual liquid crystal cells and a polarizing plate is attached to the outside of the substrate to form a display, the above-described orientation distribution directly leads to the contrast distribution of the liquid crystal, resulting in variations in display quality. . That is, in FIG. 4, when the polarizing plates are attached with the arrows A and B as the optimum directions, the arrows A− and B− cause a deviation of the angle −Φ, and the arrows A + and B + cause a deviation of the angle + Φ. When a ferroelectric liquid crystal is used, the polarization axis of the polarizing plate is shifted from the arrows A and B by the cone angle θ of the ferroelectric liquid crystal so that the layer direction of the liquid crystal molecules overlaps the arrows A and B. Arrange. Then, a black state where light does not leak can be realized around the arrows A and B at the edge, but at the positions of the arrows A− and B− and the arrows A + and B +, the light is emitted even in the black state according to the above equation 1. Leakage and display unevenness within the same panel surface, resulting in poor display quality.

  In FIG. 4, when the size of each cell substrate is small and the number is increased accordingly, the positions AB, A−B +, A + B− belong to different panels, and the deviation in the alignment direction is caused. Will appear as misalignment between panels.

  In order to solve this problem, a method of reducing the angle Φ by reducing the size of the large substrate or increasing the distance between the large substrate and the vapor deposition source can be considered. However, when considering production efficiency, the larger the substrate, the more advantageous. The smaller the size of the vacuum evaporation machine, the less time is required for evacuation, which is advantageous in terms of productivity.

  In addition, if the individual panel size is small and the number of pieces to be taken is large, it is conceivable that a polarizing plate is stretched according to the actual orientation direction of each panel. Trimming the polarizing plate takes extra time and reduces production efficiency.

  In order to solve the above problems, the manufacturing method of the present invention employs the following method. A plurality of large substrates having a plurality of cell substrates are prepared, and a deposition process for depositing a plurality of large substrates and a projection direction of a vapor deposition beam deposited on the large substrate on the large substrate surface are Vapor deposition from two different large substrates, and a large substrate cutting process that vertically divides a large substrate along the vapor deposition center line, which is a line parallel to the edge, or the parallel line, and a plurality of divided substrates. Select two separated substrates that are arranged in the same direction from the evaporation source with respect to the center line, one by one, and bond the two separated substrates together as a pair of divided substrates so that the evaporation surfaces face each other And a process.

  In addition, a cell substrate dividing step of dividing the substrate into a plurality of pairs of cell substrates is provided after the bonding step. A liquid crystal is injected after the bonding step. The liquid crystal is a ferroelectric liquid crystal. In addition, a pair of polarizing plates arranged so that their polarization axes are orthogonal to each other are disposed outside the pair of cell substrates, and the deposition direction at a position substantially at the center of one of the cell substrates. The direction of the axis of polarization of the pair of polarizing plates is based on the normal direction of the ferroelectric liquid crystal in the central direction of the angle at which the vapor deposition direction at the substantially central position of the cell substrate intersects. It is characterized by setting. In the vapor deposition step, the vapor deposition film to be formed is SiO or SiO2.

  As described above, according to the present invention, in the manufacture of a liquid crystal panel in which a liquid crystal is sandwiched between a pair of substrates having an inorganic vapor deposition film as an alignment film on the opposite surface, the pair of substrates is against a vapor deposition source in the vapor deposition machine. By selecting and combining the same relative positions as the upper and lower substrates to form a liquid crystal panel, a liquid crystal panel with little variation in the alignment direction in the substrate can be manufactured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. 1, FIG. 2, and FIG. In the present invention, a cell substrate having the same relative position with respect to a vapor deposition source in the vapor deposition machine is selected as the upper and lower substrates and combined to constitute a liquid crystal panel. For example, when producing a two-piece panel from a large substrate, as shown in FIG. 1, the projection direction of the vapor deposition beam deposited on the large substrate onto the large substrate surface is parallel to the edge of the large substrate. 1, that is, along the vapor deposition center line of FIG. 1, with respect to the vapor deposition source 23, the cell substrate A1 on the left side of the large substrate 31a and the cell substrate A2 on the right side of the large substrate 31b The cell substrate B1 and the cell substrate B2 in the right part are divided, and the divided substrates arranged in the same position from the vapor deposition center line, that is, the left parts (cell substrates A1 and B1 in the figure) and the right part In this method, the liquid crystal cells are obtained by bonding them together (cell substrates A2 and B2 in the figure).

  As shown in FIG. 1, the cell substrate A1 that is the left portion of the large substrate 31a and the cell substrate B1 that is the left portion of the large substrate 31b, and the cell substrate A2 that is the right portion of the large substrate 31a and the right portion of the large substrate 31b. A panel A1B1 (41a) and a panel A2B2 (41b) are manufactured by combining the cell substrates B2. The upper part of FIG. 1 shows the case where the cell substrate A1 and the cell substrate of the cell substrate A2 are turned down.

Here, although the divided substrate is a single cell substrate, and in FIG. 1, each cell substrate A1 and cell substrate A2 are divided, the divided substrate may be divided so as to include a plurality of cell substrates. For example, as shown in FIG. 3A, parallel to the deposition center line, the column including the cell substrate A3 in the vertical direction, the column including the cell substrate A1, the column including the cell substrate A2,... As shown in FIG. 3, the divided substrate rows may be bonded to each other, and divided from each other and arranged in the same position from the vapor deposition center line divided in FIG. That is, a pair of divided substrates having a plurality of pairs of cell substrates (panels) may be obtained by facing the divided substrates in a row including the cell substrates A3 and the divided substrates in a row including the cell substrates B3.

  The in-plane distribution in the vapor deposition direction of the panel thus formed, for example, the panel A1B1 (41a) formed by combining on the left side of the large substrates 31a and 31b has the following characteristics. (1) Vapor deposition directions on the upper and lower substrates are crossed; (2) Crossed by twisting to the right toward the paper surface; (3) Average direction of crossing upper and lower vapor deposition directions, ie, liquid crystal The orientation direction is the angle -Φ / 2 (C- in the figure) at the left arrows A and -B, the angle + Φ / 2 (C + in the figure) at the right arrows A and B-, and the arrow at the center position of the panel De-e- is 0 degree (C in the figure).

  The panel A2B2 (41b) formed by combining the large substrates 31a and 31b on the right side has the same characteristics as the panel A1B1 (41a) except that the cloth is twisted leftward toward the paper surface.

  As described above, when the large substrate is divided into two equal parts according to the method of the present invention, the distribution in the orientation direction is about half that of the conventional method shown in FIG. Further, when further division can be performed in the left-right direction in production, the distribution in the orientation direction can be further reduced by combining divided substrates at the same relative position with respect to the vapor deposition source according to the method of the present invention.

  On the other hand, according to the present invention, the orientation directions on the upper and lower substrates always cross, and the deviation angle becomes the maximum angle Φ at both ends of the large substrate. As a result of examining how such a shift affects the alignment of the liquid crystal, it was confirmed that there is generally no influence in the range of tens of degrees, which is an expected angle at the time of vapor deposition. The cause is considered to be derived from the layer structure of the ferroelectric liquid crystal. That is, in general, a smectic liquid crystal such as a ferroelectric liquid crystal has a layer structure, and the smectic layer structure does not twist even if there is a certain amount of deviation in the alignment direction of the upper and lower substrates as in the panel of the present invention. It is uniformly oriented in the middle direction of the upper and lower substrate orientations. In addition, due to the demand from the vapor deposition substrate interface to maintain a certain pretilt, there is a shift in the alignment direction of the upper and lower substrates, as described above, coupled with the fact that the ferroelectric liquid crystal molecules remain at a certain position on the cone. This also results in no influence on the alignment of the ferroelectric liquid crystal.

  Hereinafter, the features and effects of the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

Two glass substrates (large substrate 31) having a size of 150 mm × 100 mm provided with ITO electrodes as shown in FIGS. 3A and 3B are set in a vacuum vapor deposition machine, and a film thickness of 600 mm is formed by a heat vapor deposition method. A SiO obliquely deposited film was prepared. The distance between the deposition source and the lower edge of the substrate was 1 m, and the deposition angle β was 85 degrees. The degree of vacuum during deposition and the deposition rate were 1 × 10 ⁻⁵ torr and 5 liters / second, respectively.

As shown in FIG. 3, the large-size substrates 31 were divided into columns along the line parallel to the deposition center line. In FIG. 1, only the portions of the cell substrates A1 and A2 and the portions of the cell substrates B1 and B2 of the large substrate 31 are illustrated in an enlarged manner. As shown in FIG. 1, the left substrates (cell substrate A1 and cell substrate B1) are combined with each other and the right substrates (cell substrate A2 and cell substrate B2) are combined with each other with a 1.5 mm ball spacer interposed therebetween. A cut substrate is obtained.

  Thereafter, a cell substrate cutting step is performed in which this pair of divided substrates is cut into 12 single panels, and a ferroelectric liquid crystal composition FELIX-015 / 100 manufactured by AZ Electronic Co., Ltd. is injected in an isotropic phase of 100 ° C. The temperature was lowered to room temperature at a rate of 2 ° C./min to obtain a uniform horizontal orientation. In this example, the injection was performed after dividing into individual panels, but it was not divided into individual panels, and was injected into a plurality of panels simultaneously in a state of a pair of divided substrates having a plurality of panels. A strip injection may be performed.

  To each panel, two polarizing plates that are crossed Nicols are pasted on both sides of the cell substrate so as to be shifted from the edge of the substrate by the tilt angle q (21.4 degrees) of the liquid crystal as shown in FIG. Each panel was completed.

  A black wave is measured by applying a 10 V / 100 Hz rectangular wave to each of the liquid crystal devices using the panels A1B1, A2B2, A3B3, and A4B4 thus obtained, and measuring the black transmittance. did. At the time of measurement, the non-illuminated state was 0%, and the transmittance when the two deflectors were paranicol was 100%. The transmittance of the liquid crystal device using the panel A1B1 close to the deposition center line and the liquid crystal device using the panel A2B2 was about 0.4%. On the other hand, the transmittance of panel A3B3 and panel A4B4 manufactured with cell substrates A3, A4, B3, and B4 that are farthest from the deposition center line is about 0.8%, and there is a slight light leakage, but sufficient contrast is obtained in both cases. It was a black state.

  In this embodiment, a SiO oblique deposition film was used as the deposition film, but good results were obtained even with the SiO 2 oblique deposition film.

Comparative example

  With respect to the panel A1B2 (32a) and the panel A2B1 (32b) illustrated in FIG. 4, the black transmittance was measured under the same conditions as in the example. The panel A1B2 (32a) and the panel A2B1 (32b) are manufactured by a combination of positions different from the left and right of the deposition center line and the right and left.

  The transmittance of panel A1B2 and panel A2B1 close to the deposition center line was about 0.3%. On the other hand, the transmittances of the panels A3B4 and A4B3 farthest from the deposition center line were about 2.4%, and significant light leakage occurred compared to the example. A decrease in contrast as a liquid crystal device is inevitable.

It is a panel combination figure based on the manufacturing method of this invention. It is a schematic diagram of a SiO or SiO2 oblique deposition method and a ferroelectric liquid crystal panel. It is the figure which showed the positional relationship of the large sized board | substrate provided with the several cell substrate, and a vapor deposition source. It is a panel combination figure based on the conventional manufacturing method.

Explanation of symbols

21a, 21b Substrate 22 Liquid crystal layer 23 Deposition source 24 Deposition beam 25 Deposition angle 26 Deposition direction 27 Layer normal direction 28a, 28b Stable state 29 Liquid crystal molecule 31 Large substrate 32a Panel A1B2
32b Panel A2B1
41a Panel A1B1
41b Panel A2B2

Claims (6)

A plurality of large substrates having a plurality of cell substrates are prepared, and a deposition process for depositing the plurality of large substrates,
The projection direction of the vapor deposition beam vapor-deposited on the large substrate is a vapor deposition center line which is a line parallel to the edge of the large substrate or the parallel line, and the large substrate. A large-sized substrate cutting step to obtain a plurality of divided substrates,
From the two different large substrates, two of the divided substrates that are arranged in the same position from the vapor deposition source with respect to the vapor deposition center line are selected one by one, and the two divided substrates are vapor deposited. A method of manufacturing a liquid crystal panel, comprising: a step of bonding as a pair of divided substrates so that the surfaces face each other.   The method for manufacturing a liquid crystal panel according to claim 1, further comprising a cell substrate dividing step of dividing into a plurality of pairs of cell substrates after the bonding step.   The liquid crystal panel manufacturing method according to claim 1, wherein liquid crystal is injected after the bonding step.   The method of manufacturing a liquid crystal panel according to claim 3, wherein the liquid crystal is a ferroelectric liquid crystal.   A pair of polarizing plates arranged so that their polarization axes are orthogonal to each other are disposed outside the pair of cell substrates, and the vapor deposition direction at a substantially central position of one of the cell substrates of the pair of cell substrates. And a layer normal direction of the ferroelectric liquid crystal in the central direction of the angle at which the vapor deposition direction at the substantially central position of the other cell substrate intersects, and the pair of polarized light with reference to the layer normal direction The method of manufacturing a liquid crystal panel according to claim 4, wherein the direction of the polarization axis of the plate is set. 2. The method of manufacturing a liquid crystal panel according to claim 1, wherein the vapor deposition film formed in the vapor deposition step is SiO or SiO2.

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