JP2009237444A - Method for manufacturing liquid crystal display element, nd the liquid crystal display elemnt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a liquid crystal display element provided with proper display performance. <P>SOLUTION: A first transparent conductive film is formed on a first transparent substrate, and a second transparent conductive film is formed on a second transparent substrate (step a). At least either the first transparent conductive film or the second transparent conductive film is irradiated with a laser beam, to form a portion provided with gradation, in a section or the thickness direction (step b). Alignment films are formed on the first and second transparent substrates so as to cover the first and second transparent electrodes, and alignment processing is applied to the alignment films (step c). A liquid crystal layer is formed in between the alignment films of the first and second transparent substrates (step d). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a liquid crystal display element and a liquid crystal display element.

  FIG. 9 is a flowchart showing an outline of a conventional method for manufacturing a liquid crystal display element.

  In the manufacturing process of the liquid crystal display element, first, in an evaporation process S201, an ITO film is evaporated on the glass substrate.

  Next, in a resist coating step S202, a photoresist is applied in a desired pattern on the ITO film.

  Subsequently, in step S203, the substrate coated with the photoresist is exposed with an exposure machine. After the exposure, the ITO film is patterned into a desired shape by developing, etching, and removing the photoresist.

  In step S204, alignment film application and rubbing are performed. An alignment film is applied to the ITO film surface of the glass substrate using a flexographic printing machine, an inkjet coating apparatus, or the like. In some cases, an insulating film is applied before the alignment film is applied. The applied alignment film is rubbed.

  In step S205, the two substrates that have been subjected to the alignment process by rubbing are overlapped and a liquid crystal material is injected. After the liquid crystal is injected, the injection port is sealed, and a polarizing plate is pasted on both substrates to complete a liquid crystal display element (see, for example, Patent Document 1).

  In the above-described method for manufacturing a liquid crystal display element, the entire manufacturing process of the liquid crystal display element is performed by steps S202 and S203 (steps for performing resist coating, exposure, development, etching, and peeling) for patterning the ITO film into a desired shape. To be complicated. In Steps S202 and S203, a large amount of chemicals such as a resist material, an etching solution, a stripping solution, and a cleaning solution are required. For this reason, chemical treatment equipment that reduces the influence on the surrounding environment is required, which is a major factor in increasing costs.

  In addition, since the ITO film in the portion where the photoresist is applied remains, and the ITO film in the portion where the photoresist is not applied is completely removed, a high contrast display can be displayed at the boundary between the two, but the display is blurred It is difficult to realize.

Japanese Patent Laying-Open No. 2005-300744

  The objective of this invention is providing the manufacturing method of a liquid crystal display element provided with favorable display performance.

  Moreover, it is providing the manufacturing method of a simple liquid crystal display element.

  Furthermore, it is providing the manufacturing method of the liquid crystal display element which can be implement | achieved at low cost.

  Moreover, it is providing a liquid crystal display element provided with favorable display performance.

  According to one aspect of the present invention, (a) forming a first transparent conductive film on a first transparent substrate and forming a second transparent conductive film on a second transparent substrate; Irradiating at least one of the first transparent conductive film and the second transparent conductive film with a laser beam to form a portion having gradation in the area or thickness direction; and (c) the first transparent conductive film. Forming an alignment film on the second transparent substrate so as to cover the first and second transparent conductive films, and performing an alignment treatment on the alignment film; and (d) the first and second processes. There is provided a method for manufacturing a liquid crystal display element, comprising a step of forming a liquid crystal layer between alignment films of a transparent substrate.

  According to another aspect of the present invention, a first transparent substrate on which a first electrode is formed, and a second transparent substrate on which a second electrode is formed, the first electrode, A second transparent substrate disposed so as to face the second electrode; a first alignment film formed on the first transparent substrate so as to cover the first electrode; A second alignment film formed on the second transparent substrate so as to cover the second electrode, the first alignment film of the first transparent substrate, and the second transparent substrate A liquid crystal layer sandwiched between the second alignment film and at least one of the first transparent conductive film and the second transparent conductive film has a gradation in the area or thickness direction. A liquid crystal display element including the portion is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a liquid crystal display element provided with favorable display performance can be provided.

  In addition, a simple method for manufacturing a liquid crystal display element can be provided.

  Furthermore, it is possible to provide a method for manufacturing a liquid crystal display element that can be realized at low cost.

  In addition, a liquid crystal display element having favorable display performance can be provided.

  FIG. 1 is a flowchart showing an outline of a method for manufacturing a liquid crystal display device according to an embodiment. With reference to this figure, the manufacturing method of the liquid crystal display element by 1st Example is demonstrated.

  In the vapor deposition step S101, an insulating film having a thickness of 1000 mm is formed on a transparent glass plate having a thickness of 0.7 mm, for example, and a transparent conductive film having a thickness of 2000 mm, for example, an ITO film is deposited thereon. For example, blue plate glass is used as the glass plate. The ITO film constitutes an electrode in the manufactured liquid crystal display element. Two glass substrates on which an ITO film is deposited are prepared for use in an upper substrate and a lower substrate of the liquid crystal display element.

  Next, in the laser ablation step S102, the ITO film is irradiated with a laser beam, and the ITO film is patterned (laser etching). For example, a YVO laser oscillator can be used as the laser oscillator. A pulse laser beam having a wavelength of 1064 nm emitted from the YVO laser oscillator is incident on the ITO film at a laser output of 10 to 100 W, for example, 35 W, and a repetition frequency of 10 to 100 kHz, for example, 50 kHz.

  Laser beam irradiation is performed based on CAD data created by reading an image desired to be displayed on a manufactured liquid crystal display element with a high-resolution CCD camera and binary-converting the read image data. The laser beam is incident on the ITO film while scanning with a galvanometer mirror. The ITO film at the position where the laser beam is incident is removed by an ablation action and an evaporation action by heat.

  The laser ablation step S102 includes a step of scanning a spot-like laser beam in parallel lines on the ITO film and ablating and removing the ITO film irradiated with the laser.

  FIG. 2 is a photomicrograph showing an ITO film that has been ablated in parallel lines. The black portion is the region where the ITO film remains. The outside of the stripe region (the black portion extending thickly from the upper left to the lower right in the photograph) was scanned in parallel lines with a spot laser beam, and the stripe region was to be left. The actually obtained ITO pattern was accompanied by a thin parallel line area outside the stripe area. The pitch of the remaining parallel linear regions corresponds to the pitch of the laser beam scan. It is considered that the formation of the parallel linear regions is caused by an increase in the ablation threshold because heat dissipation efficiency is high in the vicinity of the remaining stripe regions. If the laser power is increased or the repetition frequency is decreased, it is considered possible to eliminate the remaining parallel linear pattern. However, it has been found that the ITO pattern as shown in FIG. 2 can perform a faint display at the portion of the parallel line pattern. Note that the linear etching pattern can be formed in an arbitrary direction by changing the scanning direction of the laser beam.

  FIG. 3 is a graph showing the film thickness on the glass substrate in the portion subjected to the linear etching process. The horizontal axis of the graph represents a one-dimensional position in the in-plane direction of the glass substrate in the unit “μm”. The vertical axis of the graph represents the thickness of the film formed on the glass substrate in the unit “Å”.

  An ITO film is formed in a portion of about 1000 cm or more on the vertical axis of the graph. In the region where the linear pattern is formed, portions where the ITO film is not etched (thick portions that remain) and portions where the ITO film is completely removed (patterned portions) appear alternately by laser beam irradiation.

  In the laser ablation step S102, laser etching for removing the ITO film, for example, in a dot shape by switching the YVO laser oscillator on and off in a very short time is also possible. If the distribution density of dots is changed, it will be possible to realize a blurred display.

  FIG. 4 is a photomicrograph showing an ITO film that has been laser-etched in a dot shape. As shown in this figure, for example, by performing dot-like etching on the ITO film continuously, it is possible to form an electrode with a blurred display pattern.

  Note that the laser etching performed in a linear or dot shape may be performed on at least one of the two substrates prepared in the vapor deposition step S101.

  Refer to FIG. 1 again.

  In step S103, alignment film coating and rubbing are performed. After washing the glass substrate with the ITO film patterned in the previous step, an alignment film is applied and formed to a thickness of 500 to 800 mm on the ITO film surfaces of both glass substrates using, for example, a flexographic printing machine. As a material for the alignment film, for example, SE-410 manufactured by Nissan Chemical Co., Ltd. is used. In applying the alignment film, for example, a flexographic printing method is used.

  Subsequently, alignment treatment is performed on the formed alignment film, for example, by rubbing. The alignment treatment is performed, for example, so that the alignment direction of the liquid crystal molecules differs by 90 ° between the upper and lower substrates of the manufactured liquid crystal display element.

  A main sealant, such as ES-manufactured by Mitsui Chemicals Co., Ltd., in which a gap control agent such as Sekisui Chemical Co., Ltd. micromicron 5 microns is sprayed on one substrate and plastic fiber having a diameter of 5 μm, for example, is added to the other substrate. 7500 is printed using a dispenser method.

  In step S104, the two substrates subjected to the alignment treatment are superposed and baked in a pressed state, and then the substrate is divided into a predetermined size and liquid crystal is injected in a vacuum. As the liquid crystal material, for example, a nematic liquid crystal material having a positive optical anisotropy (mixture Δn = 0.15) manufactured by Dainippon Ink and Chemicals, Inc. can be used.

  After the liquid crystal injection, the injection port is sealed to produce a liquid crystal cell. After washing the liquid crystal cell, a polarizing plate is stuck on both substrates so as to have a crossed Nicol arrangement, thereby completing a liquid crystal display element.

  With reference to FIGS. 5A to 5D, a liquid crystal display device manufactured by the manufacturing method according to the first embodiment will be described.

  FIG. 5A is a schematic cross-sectional view of a liquid crystal display device manufactured by the manufacturing method according to the first embodiment. The glass substrates 12 and 18 are disposed to face each other substantially in parallel. A common electrode 13 is formed of ITO on the glass substrate 12, and a segment electrode 17 is formed of ITO on the glass substrate 18. An alignment film 14 is formed on the glass substrate 12 so as to cover the common electrode 13, and an alignment film 16 is formed on the glass substrate 18 so as to cover the segment electrode 17. The alignment films 14 and 16 are rubbed. The liquid crystal layer 15 is disposed between the upper substrate including the glass substrate 12, the common electrode 13, and the alignment film 14 and the lower substrate including the glass substrate 18, the segment electrode 17, and the alignment film 16. Is pinched. Polarizing plates 11 and 19 are arranged in crossed Nicols on the surface of the glass substrates 12 and 18 opposite to the surface on which the liquid crystal layer 15 is formed.

  FIG. 5B shows an example of a cross section of the segment electrode 17 on which a linear pattern is formed. The cross section of this figure shows a plurality of recesses from which the segment electrode (ITO film) 17 has been completely removed in the thickness direction. Each of the plurality of recesses extends while gradually reducing the width in the vertical direction of the drawing, and constitutes one linear pattern region.

  The segment electrode 17 also includes an electrode complete removal region configured in a dot shape. Moreover, the common electrode 13 may have an electrode complete removal region configured in a linear or dot shape.

  FIG. 5C shows an example of a display realized by the liquid crystal display device manufactured by the manufacturing method according to the first embodiment as a micrograph. On the left side of the photograph, a faint display as if written with a brush, which is realized by an area where a linear pattern is formed on the electrode, is confirmed.

  FIG. 5D is a schematic plan view showing a linear pattern region of the electrode. The electrode 17 has a gradation in terms of area. That is, the electrode 17 includes a linear portion that is formed narrower toward the electrode non-forming region. It is considered that the fading display is caused by a voltage difference between the root portion and the tip portion of the tapered linear portion when a voltage is applied to the liquid crystal display element.

  Conventionally, a high-resolution TFT-LCD and an expensive driving circuit have been required to perform a faint display as shown in FIG. 5C by dot matrix driving. According to the method for manufacturing a liquid crystal display element according to the first embodiment, a liquid crystal display element having good display performance can be manufactured at low cost.

  In addition, what extends in the left-right direction on the lower side of the photograph shown in FIG. 5C is a linear display realized by etching in a dot shape.

  Next, a method for manufacturing a liquid crystal display element according to the second embodiment will be described.

  In the vapor deposition step S101, for example, an insulating film having a thickness of 1000 mm is formed on a glass plate having a thickness of 0.7 mm, and an ITO film having a thickness of 2000 mm is deposited thereon. For example, blue plate glass is used as the glass plate. In the vapor deposition step S101, two glass substrates on which the ITO film is deposited are prepared.

  In the laser ablation step S102, the ITO film is irradiated with a laser beam, and the ITO film is patterned (laser etching). For example, a YVO laser oscillator is used as the laser oscillator. A pulse laser beam having a wavelength of 1064 nm emitted from the YVO laser oscillator is incident on the ITO film with a laser output of 10 to 100 W and a repetition frequency of 10 to 100 kHz.

  Laser beam irradiation is performed based on CAD data created by reading an image desired to be displayed on a manufactured liquid crystal display element with a high-resolution CCD camera and converting it to a gradation state. The gradation state can be classified into any number of stages, but in this embodiment, the data is divided into four stages of complete white, slightly dark white, slightly bright black, and complete black, and according to each gradation. The ITO film was irradiated with a laser beam while scanning under different laser beam irradiation conditions.

  The complete white part was irradiated 30 times with a laser output of 30 W and a repetition frequency of 40 kHz.

  A slightly dark white part was irradiated 30 times with a laser output of 27 W and a repetition frequency of 30 kHz.

  The slightly bright black part was irradiated 30 times with a laser output of 15 W and a repetition frequency of 20 kHz.

  The complete black part was not irradiated with the laser beam.

  FIG. 6A is a graph showing the removal depth of the ITO film by laser beam irradiation. The horizontal axis of the graph represents a one-dimensional position in the in-plane direction of the glass substrate in the unit “μm”. The vertical axis of the graph represents the removal depth of the ITO film in the unit “Å”.

  In the range shown in this figure, the laser film is not irradiated to the position of about 610 μm or less and the position (complete black portion) of about 1630 μm or more, and the ITO film is not removed.

  At the position of about 610 μm to about 1300 μm (slightly bright black portion), the ITO film is removed over a removal depth of about 500 mm to about 1500 mm.

  At a position of about 1300 μm to about 1560 μm (a slightly dark white portion), the ITO film is removed to a depth of about 1500 mm.

  At the position of about 1560 μm to about 1600 μm (complete white portion), the ITO film is completely removed.

  From the graph shown in this figure, the ITO film at the position where the laser beam is incident is removed to a depth corresponding to the irradiation condition of the laser beam, and in the region irradiated under the same irradiation condition, it is almost the same. It can be seen that a surface condition is obtained. By performing laser etching while changing the energy and light intensity of the laser beam thus irradiated, a plurality of regions having different depths are formed in the ITO film.

  Note that, at a position of about 610 μm to about 1300 μm (slightly bright black portion), the removal depth has a width, and intense unevenness with an elevation difference of about 1000 mm occurs on the surface of the ITO film. This is considered to be because, for example, the ease of laser etching varies depending on the position on the ITO film due to the difference in crystallinity.

  Subsequent steps, that is, alignment film application and rubbing treatment in step S103, superposition, liquid crystal injection, sealing, and polarizing plate sticking in step S104 are the same as those in the first embodiment. Thus, a liquid crystal display element is manufactured by the manufacturing method according to the second embodiment.

  The schematic structure of the liquid crystal display element manufactured by the manufacturing method according to the second embodiment is the same as that of the liquid crystal display element shown in FIG. However, at least one of the common electrode 13 and the segment electrode 17 includes one or a plurality of regions that are partially removed in the thickness direction as illustrated in FIG.

  FIG. 7 is a photomicrograph showing a display example of the liquid crystal display device manufactured by the manufacturing method according to the second embodiment.

  By changing the energy and light intensity of the irradiating laser beam and increasing the removal depth of the ITO film from zero to complete removal, display of complete black, slightly bright black, slightly dark white, and complete white in order. It was confirmed that can be realized. In addition, it is also recognized that a faint display like written with a brush is realized from this photograph.

  In the liquid crystal display element according to the second embodiment, the thickness of the electrode varies depending on the position on the electrode, the resistance of the electrode varies depending on the thickness, and the light transmittance varies. Therefore, it is possible to realize gradation display, display with a difference in shading, and faint display as if written with a brush.

  Note that the change in transmitted light intensity observed in the examples was predicted to be due to the voltage gradient based on the change in electrode film thickness, but the measured value of the change in transmitted light intensity exceeded that range, so the film thickness variation In addition, it is considered that the electrode thinned by laser irradiation causes a change in the crystal state due to its thermal action, the resistivity increases, and the increase in voltage gradient is affected.

  Furthermore, as shown in this photograph, a display divided into island shapes can be realized by a combination with the electrode pattern on the counter substrate.

  FIG. 8 shows an example of a display that can be realized by forming portions with different thicknesses on the electrodes.

  The figure shown in this figure is composed of four areas 20a to 20d having different display densities. The display of the region 20a is realized by a portion where the segment electrode is not removed in the thickness direction. The display of the region 20b is realized by a portion in which the segment electrode is half-removed in the thickness direction in a dot shape. The display of the region 20c is realized by a portion where the segment electrode is removed in the thickness direction by 80 to 95% in a dot shape. Further, the display of the region 20d is realized by a portion where the segment electrode is completely removed in the thickness direction.

  In this way, by removing the part of the electrodes, various gradational displays are possible.

  The liquid crystal display element according to the second embodiment is a liquid crystal display element that realizes display of four gradations. By changing the irradiation conditions of the laser beam incident on the ITO film, for example, conditions such as wavelength, laser output, repetition frequency, etc., it is possible to realize further multi-gradation display.

  In the method of manufacturing the liquid crystal display element according to the second embodiment, the laser beam was scanned with the laser beam irradiation condition constant for each gradation to be realized. Even in a single scan, multi-gradation display is possible by changing the laser beam irradiation conditions as needed depending on the location.

  The manufacturing method of the liquid crystal display element according to the first and second embodiments does not include a photolithography process. For this reason, a liquid crystal display element can be produced easily and at low cost.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not limited to these.

  For example, in the embodiment, etching is performed using a pulsed laser beam having a wavelength of 1064 nm emitted from a YVO laser oscillator. However, a YAG laser oscillator can be used instead of the YVO laser oscillator. Moreover, it is possible to use not only the fundamental wave of the YVO laser or YAG laser but also the second harmonic, the third harmonic, and the like. For example, a laser beam having a wavelength of 532 nm or 355 nm can be used.

  In the embodiment, the laser beam is scanned by the galvano scanner, but DMD may be used for scanning the laser beam. Further, the stage on which the substrate is placed can be driven to change the incident position of the laser beam.

  Furthermore, in the embodiment, the cell thickness of the liquid crystal display element is 5 μm, but the cell thickness is not limited to this. For example, it can be 2 μm to 12 μm.

  Further, although a liquid crystal material having positive optical anisotropy is used, a liquid crystal material having negative optical anisotropy may be used.

  Furthermore, the alignment film can also be formed using a high pretilt alignment film material. It is also possible to use a vertical alignment film.

  Moreover, although the liquid crystal display element by an Example is TN-LCD, it is good also as STN-LCD and PN-LC. The display mode can also be set to the VA mode.

  Furthermore, a method of separating and gradually displaying electrode patterns may be employed. For example, when displaying characters, the display can be changed according to the order of writing.

  In addition, image data such as artworks, photographs, and handwritten nameplates can be captured and displayed.

  It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like are possible.

  It can be used for all liquid crystal display devices such as in-vehicle displays.

It is a flowchart which shows the outline of the manufacturing method of the liquid crystal display element by an Example. It is a microscope picture which shows the ITO film | membrane which was ablated in the parallel line shape. It is a graph which shows the film thickness on the glass substrate of the part to which the linear etching process was performed. It is a microscope picture which shows the ITO film | membrane which was laser-etched in the dot shape. (A)-(D) are the figures for demonstrating the liquid crystal display element manufactured with the manufacturing method by a 1st Example. (A) is a graph which shows the removal depth of the ITO film | membrane by irradiation of a laser beam, (B) is sectional drawing which shows a glass substrate and an electrode. It is a microscope picture which shows the example of a display of the liquid crystal display element manufactured with the manufacturing method by a 2nd Example. It is a figure which shows an example of the display which can be implement | achieved by forming the part from which thickness differs mutually in an electrode. It is a flowchart which shows the outline of the manufacturing method of the conventional liquid crystal display element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Polarizing plate 12 Glass substrate 13 Common electrode 14 Alignment film 15 Liquid crystal layer 16 Alignment film 17 Segment electrode 18 Glass substrate 19 Polarizing plate

Claims (5)

(A) forming a first transparent conductive film on a first transparent substrate and forming a second transparent conductive film on a second transparent substrate;
(B) irradiating at least one of the first transparent conductive film and the second transparent conductive film with a laser beam to form a portion having gradation in the area or thickness direction;
(C) forming an alignment film on the first and second transparent substrates so as to cover the first and second transparent conductive films, and performing an alignment treatment on the alignment film;
(D) forming a liquid crystal layer between the alignment films of the first and second transparent substrates.   The method of manufacturing a liquid crystal display element according to claim 1, wherein in the step (b), a linear portion having an area gradation that becomes narrower toward the tip end portion is formed.   The method for manufacturing a liquid crystal display element according to claim 1, wherein in the step (b), the gradation is formed in the thickness direction by changing a laser beam irradiation condition. A first transparent substrate on which a first electrode is formed;
A second transparent substrate on which a second electrode is formed, wherein the first transparent electrode is disposed so that the first electrode and the second electrode face each other;
A first alignment film formed on the first transparent substrate so as to cover the first electrode;
A second alignment film formed on the second transparent substrate so as to cover the second electrode;
A liquid crystal layer sandwiched between the first alignment film of the first transparent substrate and the second alignment film of the second transparent substrate;
A liquid crystal display element including a portion in which at least one of the first transparent conductive film and the second transparent conductive film has a gradation in an area or thickness direction.   5. The liquid crystal display element according to claim 4, wherein at least one of the first transparent conductive film and the second transparent conductive film includes a linear portion having an area gradation that becomes narrower toward a tip portion.