WO2014196495A1 - Procédé de fabrication d'un dispositif d'affichage à cristaux liquides - Google Patents

Procédé de fabrication d'un dispositif d'affichage à cristaux liquides Download PDF

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Publication number
WO2014196495A1
WO2014196495A1 PCT/JP2014/064586 JP2014064586W WO2014196495A1 WO 2014196495 A1 WO2014196495 A1 WO 2014196495A1 JP 2014064586 W JP2014064586 W JP 2014064586W WO 2014196495 A1 WO2014196495 A1 WO 2014196495A1
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liquid crystal
crystal display
alignment
crystal layer
display device
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PCT/JP2014/064586
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English (en)
Japanese (ja)
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岩井　道記
菊池　克浩
永田　尚志
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シャープ株式会社
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1343—Electrodes
    • G02F1/134309—Electrodes characterised by their geometrical arrangement
    • G02F1/134363—Electrodes characterised by their geometrical arrangement for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133707—Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133753—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
    • G02F1/133761—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle with different pretilt angles

Definitions

  • the present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a method for manufacturing a liquid crystal display device having an alignment maintaining layer.
  • liquid crystal display device having a wide viewing angle characteristic has been developed and widely used as a monitor for a personal computer, a display device for a personal digital assistant device, or a television receiver.
  • a display mode using a vertically aligned liquid crystal layer As a display mode for realizing a wide viewing angle, a display mode using a vertically aligned liquid crystal layer (referred to as “VA mode”) is known.
  • VA mode a display mode using a vertically aligned liquid crystal layer
  • Patent Document 1 discloses a kind of VA mode liquid crystal display device in Patent Document 1.
  • a plurality of liquid crystal domains are formed in a pixel when a voltage is applied, and liquid crystal molecules are radially inclined and aligned (that is, have an axially symmetric alignment) in each liquid crystal domain.
  • the display mode using the characteristic alignment state disclosed in Patent Document 1 is called a CPA (Continuous Pinwheel Alignment) mode.
  • CPA Continuous Pinwheel Alignment
  • the pixel electrode is divided into a plurality of subpixel electrodes (referred to as “unit solid portion” in Patent Document 1) by notches or openings, and an edge portion of the subpixel electrode is applied when a voltage is applied.
  • An axisymmetric orientation is formed using an oblique electric field generated in the above.
  • Patent Document 2 proposes a configuration in which an alignment regulating structure is provided on the liquid crystal layer side of the counter substrate in order to stabilize the axially symmetric alignment.
  • Patent Document 2 describes a protrusion protruding toward the liquid crystal layer and an opening formed in the counter electrode as an alignment regulating structure.
  • PSA technology Polymer Sustained Alignment Technology
  • the pretilt direction of liquid crystal molecules is controlled by a photopolymer formed on an alignment film.
  • the photopolymerization compound is obtained by mixing a small amount of a photopolymerizable compound (for example, photopolymerizable monomer) in a liquid crystal material, assembling a liquid crystal cell, and applying a predetermined voltage to the liquid crystal layer. It is formed by irradiating with UV rays.
  • the alignment state of the liquid crystal molecules when the photopolymer is formed is maintained (stored) by the photopolymer even after the voltage is removed (when no voltage is applied), improving alignment stability and response speed.
  • the layer composed of the photopolymerized product is referred to as an alignment maintaining layer (Alignment Sustaining Layer) in the present specification.
  • the process (process) for forming the alignment maintaining layer by irradiating the liquid crystal layer with light (ultraviolet rays) in a voltage applied state is referred to as a PSA process (process) in the present specification.
  • Patent Document 5 discloses a CPA mode liquid crystal display device to which the PSA technology is applied.
  • 20 and 21 show a liquid crystal display device 800 disclosed in Patent Document 5.
  • FIG. FIG. 20 is a plan view schematically showing a region corresponding to one pixel of the liquid crystal display device 800.
  • FIG. 21 is a cross-sectional view taken along line 21A-21A ′ in FIG. 20, and shows a state where no voltage is applied to the liquid crystal layer (a state where a voltage lower than the threshold voltage is applied). .
  • the liquid crystal display device 800 includes a liquid crystal display panel 800a and includes a plurality of pixels arranged in a matrix.
  • the liquid crystal display panel 800a includes an active matrix substrate 810, a counter substrate 820 facing the active matrix substrate 810, and a vertical alignment type liquid crystal layer 830 provided between the active matrix substrate 810 and the counter substrate 820. Yes.
  • the active matrix substrate 810 includes a transparent substrate 810a and pixel electrodes 811 provided on the transparent substrate 810a.
  • the active matrix substrate 810 further includes a TFT (not shown) electrically connected to the pixel electrode 811 and a wiring group including a wiring for supplying a signal to the TFT as a switching element.
  • the wiring group includes a scanning wiring 812 that supplies a scanning signal to the TFT, a signal wiring 813 that supplies a video signal to the TFT, and an auxiliary capacitance wiring 814 for forming an auxiliary capacitance.
  • the pixel electrode 811 is disposed in each of the plurality of pixels, and is formed on the interlayer insulating film 815 that covers the wiring group and the TFT.
  • the counter substrate 820 includes a transparent substrate 820a and a counter electrode 821 provided on the transparent substrate 820a.
  • a color filter layer 822 is provided between the transparent substrate 820a and the counter electrode 821.
  • the pixel electrode 811 is disposed in each of the plurality of pixels, the counter electrode 821 is typically formed as one transparent conductive film that faces all the pixel electrodes 811.
  • a vertical alignment film (not shown) is provided on the surfaces of the active matrix substrate 810 and the counter substrate 820 on the liquid crystal layer 830 side.
  • a pair of polarizing plates arranged in a crossed Nicol state is provided outside the active matrix substrate 810 and the counter substrate 820.
  • the liquid crystal layer 830 includes liquid crystal molecules 831 having negative dielectric anisotropy.
  • the liquid crystal molecules 831 in the liquid crystal layer 830 are aligned substantially perpendicular to the surface of the vertical alignment film when no voltage is applied to the liquid crystal layer 830.
  • the pixel electrode 811 of the liquid crystal display device 800 has a plurality of sub-pixel electrodes 811a.
  • FIGS. 22 and 23 show the alignment state of the liquid crystal molecules 831 when a predetermined voltage (voltage higher than the threshold voltage) is applied between the pixel electrode 811 and the counter electrode 821.
  • a predetermined voltage voltage higher than the threshold voltage
  • FIGS. 22 and 23 show the alignment state of the liquid crystal molecules 831 when a predetermined voltage (voltage higher than the threshold voltage) is applied between the pixel electrode 811 and the counter electrode 821.
  • a predetermined voltage voltage higher than the threshold voltage
  • a liquid crystal domain having an axially symmetric orientation is formed for each subpixel electrode 811a because the subpixel electrode 811a has an outer edge close to an independent island, and an oblique electric field generated at an edge portion of the subpixel electrode 811a. This is because the alignment regulating force of the liquid crystal molecules 831 acts on the liquid crystal molecules 831.
  • the electric field generated at the edge of the sub-pixel electrode 811a is inclined toward the center of the sub-pixel electrode 811a and acts to orient the liquid crystal molecules 831 in an axial symmetry.
  • the pixel electrode 811 of the liquid crystal display device 800 has an opening 811b formed at substantially the center of each of the plurality of sub-pixel electrodes 811a.
  • each edge portion of the plurality of subpixel electrodes 811 a overlaps a wiring group, that is, the scanning wiring 812, the signal wiring 813, and the auxiliary capacitance wiring 814.
  • the liquid crystal layer 830 of the liquid crystal display device 800 includes an alignment maintaining layer (polymer structure) 832 for defining the alignment direction of the liquid crystal molecules 831 as schematically shown in FIG.
  • the alignment maintaining layer 832 is a vertical alignment film formed by previously mixing a photopolymerizable compound in the liquid crystal material constituting the liquid crystal layer 830 and polymerizing the photopolymerizable compound in a state where a voltage is applied to the liquid crystal layer 832. Formed on top. Since the alignment state of the liquid crystal molecules 831 when the alignment maintaining layer 832 is formed is maintained (stored) even after the voltage is removed (a state where no voltage is applied), alignment stability and response speed are improved.
  • FIG. 24 shows an optical microscope image when the liquid crystal display device 800 of Patent Document 5 is actually prototyped and observed in a state where a voltage is applied to the liquid crystal layer 830 so that the liquid crystal molecules 831 are axially aligned.
  • FIG. 25 (a) shows an enlarged image of the vicinity of the region surrounded by the broken-line circle in FIG. 24, and
  • FIG. 25 (b) shows the liquid crystal molecules 831 in the portion shown in FIG. 25 (a).
  • An orientation direction is shown typically.
  • a polarizing plate a pair of linear polarizing plates is provided, and these linear polarizing plates display one polarization axis (transmission axis) PA1 as shown in FIG. Parallel to the horizontal direction of the screen, the other polarization axis (transmission axis) PA2 is arranged in crossed Nicols so as to be parallel to the vertical direction of the display surface.
  • the symmetry of the alignment of the liquid crystal molecules 831 is broken (the cross-shaped extinction pattern is deformed so as to be dragged downward), and the desired axial symmetry is obtained. It can be seen that no orientation is obtained. It can also be seen that the state of axial symmetry differs between pixels.
  • the display quality may be deteriorated due to the disorder of the tilt alignment.
  • the present invention has been made in view of the above problems, and its purpose is to improve the efficiency of a VA mode liquid crystal display device to which the PSA technology is applied while suppressing deterioration in display quality due to disorder of tilt alignment.
  • An object of the present invention is to provide a manufacturing method that can be manufactured well.
  • a method for manufacturing a liquid crystal display device includes a first substrate, a second substrate, and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate.
  • the liquid crystal molecules of the liquid crystal layer are inclined and aligned in a plurality of directions in each of the plurality of pixels, and the liquid crystal display panel
  • a pair of vertical alignment films provided between the pixel electrode and the liquid crystal layer and between the counter electrode and the liquid crystal layer, and photopolymerization on a surface of each of the pair of vertical alignment films on the liquid crystal layer side Orientation-maintaining layer formed from material
  • An alignment maintaining layer that defines a pretilt azimuth and a pre-tilt angle of the liquid crystal molecules when no voltage is applied to the liquid crystal layer, the method for manufacturing a
  • step (B) forming the alignment maintaining layer by polymerizing the photopolymerizable compound in the liquid crystal layer, and the step (B) includes between the pixel electrode and the counter electrode. Irradiating the liquid crystal layer with light in a state where a first potential difference is applied to the pretilt defined by the alignment maintaining layer while increasing a pre-tilt angle defined by the alignment maintaining layer. After the step (B-1) for substantially determining the orientation and the step (B-1), a second potential difference larger than the first potential difference is applied between the pixel electrode and the counter electrode. And (B-2) further increasing the pre-tilt angle by irradiating the liquid crystal layer with light in a heated state.
  • the first potential difference is determined by the symmetry of the tilt alignment of the liquid crystal molecules in each of the plurality of pixels, the potential difference given between the pixel electrode and the counter electrode being the first potential difference. Is set to be substantially the highest.
  • the second potential difference is not less than 1.2 times and not more than 15 times the first potential difference.
  • the pre-tilt angle after performing the step (B-2) is not less than 1.2 times and not more than 6 times the pre-tilt angle immediately after performing the step (B-1). .
  • the pre-tilt angle immediately after performing the step (B-1) is 0.7 ° or more.
  • the liquid crystal molecules when a predetermined voltage is applied to the liquid crystal layer, the liquid crystal molecules are axially symmetric in each of the plurality of pixels.
  • the pixel electrode is formed between at least one cross-shaped trunk, a plurality of branches extending in a direction of approximately 45 ° from the at least one cross-shaped trunk, and the plurality of branches.
  • a plurality of slits are provided.
  • Another method of manufacturing a liquid crystal display device includes a first substrate, a second substrate, and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate.
  • the liquid crystal display panel includes a plurality of pixels arranged in a matrix, the first substrate includes a pixel electrode provided on each of the plurality of pixels, and the second substrate includes the pixel electrode.
  • the liquid crystal molecules in the liquid crystal layer are inclined and aligned in a plurality of directions in each of the plurality of pixels when a predetermined voltage is applied to the liquid crystal layer.
  • the panel includes a pair of vertical alignment films provided between the pixel electrode and the liquid crystal layer and between the counter electrode and the liquid crystal layer, and a liquid crystal layer side surface of each of the pair of vertical alignment films.
  • An alignment maintaining layer that defines a pretilt azimuth and a pre-tilt angle of the liquid crystal molecules when no voltage is applied to the liquid crystal layer, and the pair of vertical alignment films includes a pair of A method of manufacturing a liquid crystal display device which is a photo-alignment film, the step (A) of preparing the liquid crystal display panel containing a photopolymerizable compound in the liquid crystal layer, the pixel electrode of the liquid crystal display panel, and the facing (B) forming the alignment maintaining layer by irradiating the liquid crystal layer with light and polymerizing the photopolymerizable compound in the liquid crystal layer in a state where a potential difference is applied between the electrodes.
  • the step (A) includes irradiating one photo-alignment film of the pair of photo-alignment films with light to thereby define a plurality of regions defining different pretilt directions on the one photo-alignment film.
  • Forming step (A 1) and a step of forming a plurality of regions defining different pretilt directions in the other photo-alignment film by irradiating light to the other photo-alignment film of the pair of photo-alignment films (A 2), and the steps (A-1) and (A-2) are performed such that a pre-tilt angle defined by the pair of photo-alignment films is equal to or greater than a predetermined magnitude, Thereby, the pretilt azimuth
  • the steps (A-1) and (A-2) are performed such that a pre-tilt angle defined by the pair of photo-alignment films is 2 ° or more.
  • the first substrate and the second substrate are bonded to each other via a sealant, and then It further includes a step (A-3) of curing the sealing agent by heating.
  • a pre-tilt angle defined by the pair of photo-alignment films immediately after performing the step (A-3) is 0.7 ° or more.
  • a manufacturing method capable of efficiently manufacturing a VA mode liquid crystal display device to which the PSA technology is applied while suppressing deterioration in display quality due to disorder of tilt alignment.
  • FIG. 2 is a plan view schematically showing a region corresponding to one pixel of the liquid crystal display device 100 in the embodiment of the present invention.
  • FIG. 2 is a diagram schematically showing a liquid crystal display device 100, and is a cross-sectional view taken along line 2A-2A ′ in FIG.
  • (A) is a top view which shows typically the area
  • (A) is a figure which shows the convex part 23 used as an orientation control structure
  • (b) is a figure which shows the opening part 21a used as an orientation control structure.
  • FIG. (A) is a graph showing a change in potential difference (relationship between time and potential difference) applied between the pixel electrode 11 and the counter electrode 21 in steps (B-1) and (B-2), (b) These are graphs showing changes in the pre-tilt angle (relationship between time and pre-tilt angle) defined by the alignment maintaining layers 18 and 28 in steps (B-1) and (B-2). It is an optical microscope image when actually prototyping the liquid crystal display device 100 and observing in a state where a voltage is applied to the liquid crystal layer 30 so that the liquid crystal molecules 31 are axially symmetrically aligned.
  • (A) is the figure which expanded the area
  • (b) is a figure which shows typically the orientation direction of the liquid crystal molecule 31 in the part shown to (a).
  • (A) to (d) are diagrams showing alignment states immediately before the start of step (B-1), immediately after the end of step (B-1), immediately before the start of step (B-2), and immediately after the end of step (B-2).
  • (Optical microscope image) is a figure which shows the example of the orientation state in the comparative example 1
  • (b) is a figure which shows the example of the orientation state in the comparative example 2 and the Example 1.
  • FIG. 13 is a diagram schematically showing a liquid crystal display device 100A, and is a cross-sectional view taken along line 13A-13A ′ in FIG. It is a figure for demonstrating the relationship between the specific structure of 11 A of pixel electrodes with which liquid crystal display device 100A is provided, and the direction of the director of each liquid crystal domain.
  • FIG. 18 is a diagram for explaining a method of dividing the pixel region P shown in FIG. 17, (a) shows the pretilt direction on the active matrix substrate 10 side, (b) shows the pretilt direction on the counter substrate 20 side, c) shows the tilt direction when a voltage is applied to the liquid crystal layer 30.
  • FIG. 10 is a plan view schematically showing a region corresponding to one pixel of a liquid crystal display device 800 disclosed in Patent Document 5.
  • FIG. 21 is a diagram schematically showing a liquid crystal display device 800, and is a cross-sectional view taken along line 21A-21A 'in
  • FIG. 11 is a plan view schematically showing a region corresponding to one pixel of the liquid crystal display device 800, and shows a state in which a predetermined voltage is applied to the liquid crystal layer 830.
  • FIG. 24 is a diagram schematically showing a liquid crystal display device 800, and is a cross-sectional view taken along line 23A-23A ′ in FIG.
  • FIG. 6 is an optical microscope image obtained by actually prototyping the liquid crystal display device 800 of Patent Document 5 and observing in a state where a voltage is applied to the liquid crystal layer 830 so that the liquid crystal molecules 831 are aligned in axial symmetry.
  • (A) is the figure which expanded the area
  • (b) is a figure which shows typically the orientation direction of the liquid crystal molecule 831 in the part shown to (a). It is.
  • (A) is a figure which shows the state of the inclination alignment at the time of applying the voltage of +/- 4V to a liquid crystal layer in the case of PSA processing,
  • (b) is a voltage of +/- 10V to the liquid crystal layer in the case of PSA processing.
  • the inventor of the present application has obtained the following knowledge as a result of examining the reason why disorder of tilt alignment occurs in a VA mode liquid crystal display device to which the PSA technology is applied.
  • the state of the tilted alignment during the PSA process varies depending on the potential difference between the pixel electrode and the counter electrode (that is, the voltage applied to the liquid crystal layer).
  • the tilt alignment is disturbed by applying a high voltage to the liquid crystal layer during the PSA process, and the alignment maintaining layer is formed in this state, thereby deteriorating the display quality as described above. It seems that he was doing.
  • the high voltage was applied during the PSA process to shorten the processing tact time and reduce the risk of bubble defects (due to gas generated by material decomposition) due to ultraviolet irradiation. This is to make it happen.
  • FIG. 26A shows the state of tilted alignment when a voltage of ⁇ 4 V is applied to the liquid crystal layer during the PSA process.
  • FIG. 26B shows the state of tilted alignment when a voltage of ⁇ 10 V is applied to the liquid crystal layer during the PSA process.
  • the conventional manufacturing method cannot efficiently manufacture the VA mode liquid crystal display device to which the PSA technology is applied while suppressing the deterioration in display quality due to the disorder of the tilt alignment. .
  • FIG. 1 is a plan view schematically showing a region corresponding to one pixel of the liquid crystal display device 100.
  • FIG. 2 is a cross-sectional view taken along line 2A-2A ′ in FIG. 1, showing a state in which no voltage is applied to the liquid crystal layer 30 (a state in which a voltage less than the threshold voltage is applied). Yes.
  • the liquid crystal display device 100 includes a liquid crystal display panel 100a and includes a plurality of pixels arranged in a matrix.
  • the liquid crystal display panel 100a includes an active matrix substrate (first substrate) 10, a counter substrate (second substrate) 20 facing the active matrix substrate 10, and a vertical alignment provided between the active matrix substrate 10 and the counter substrate 20.
  • Type liquid crystal layer 30 is provided between the active matrix substrate 10 and the counter substrate 20.
  • the active matrix substrate 10 includes a transparent substrate (for example, a glass substrate) 10a and a pixel electrode 11 provided on the transparent substrate 10a.
  • the active matrix substrate 11 further includes a TFT (not shown) electrically connected to the pixel electrode 11 and a wiring group including a wiring for supplying a signal to the TFT as a switching element.
  • the wiring group includes a scanning wiring 12 for supplying a scanning signal to the TFT, a signal wiring 13 for supplying a video signal to the TFT, and a predetermined voltage (Cs voltage) applied to one of a pair of electrodes constituting the auxiliary capacitor.
  • the auxiliary capacitance wiring 14 for supplying is included.
  • the pixel electrode 11 is provided in each of the plurality of pixels, and is formed on the interlayer insulating film 15 covering the wiring group and the TFT.
  • the counter substrate 20 includes a transparent substrate 20 a (for example, a glass substrate) and a counter electrode 21 provided on the transparent substrate 20 a and facing the pixel electrode 11.
  • a color filter layer 22 is provided between the transparent substrate 20 a and the counter electrode 21.
  • the pixel electrode 11 is provided in each of the plurality of pixels, the counter electrode 21 is typically formed as one transparent conductive film that faces all the pixel electrodes 11.
  • a vertical alignment film 16 is formed between the pixel electrode 11 and the liquid crystal layer 30.
  • a vertical alignment film 26 is also formed between the counter electrode 21 and the liquid crystal layer 30. That is, the liquid crystal display panel 100a is provided with a pair of vertical alignment films 16 and 26.
  • the liquid crystal layer 30 includes liquid crystal molecules 31 having negative dielectric anisotropy, and further includes a chiral agent as necessary.
  • the liquid crystal molecules 31 in the liquid crystal layer 30 are aligned substantially perpendicular to the surfaces of the vertical alignment films 16 and 26 when no voltage is applied to the liquid crystal layer 30.
  • a pair of polarizing plates are provided so as to face each other with the liquid crystal layer 30 interposed therebetween.
  • Each of the pair of polarizing plates may be a linear polarizing plate or a circular polarizing plate.
  • the pixel electrode 11 of the liquid crystal display device 100 has a plurality of sub-pixel electrodes 11a. More specifically, the pixel electrode 11 is divided into two sub-pixel electrodes 11a by two notches (slits) 11b.
  • the pixel electrode 11 having two subpixel electrodes 11a is illustrated, but the pixel electrode 11 may include three or more subpixel electrodes 11a.
  • each subpixel electrode 11a has a substantially rectangular shape having arcuate corners, but the shape of the subpixel electrode 11a is not limited to this.
  • the subpixel electrode 11a may be rectangular or circular, for example.
  • FIGS. 3A and 3B show the alignment state of the liquid crystal molecules 31 when a predetermined voltage (voltage higher than the threshold voltage) is applied to the liquid crystal layer 30.
  • a predetermined voltage voltage higher than the threshold voltage
  • FIGS. 3A and 3B show the liquid crystal molecules 31 when a predetermined voltage is applied to the liquid crystal layer 30.
  • the liquid crystal molecules 31 are inclined and aligned in a plurality of directions in each pixel. More specifically, as shown in FIGS. 3A and 3B, a liquid crystal domain is formed on each sub-pixel electrode 11a, and the liquid crystal molecules 31 are aligned in an axially symmetric orientation (axisymmetric) in the liquid crystal domain. Orientation or radial gradient orientation).
  • a liquid crystal domain having an axially symmetric orientation is formed for each subpixel electrode 11a because the subpixel electrode 11a has an outer edge close to an independent island, and an oblique electric field generated at the edge of the subpixel electrode 11a. This is because the alignment regulating force acts on the liquid crystal molecules 31.
  • the electric field generated at the edge portion of the sub-pixel electrode 11a is inclined toward the center of the sub-pixel electrode 11a and acts to orient the liquid crystal molecules 31 in an axially symmetrical manner.
  • an alignment regulating structure on the liquid crystal layer 30 side of the counter substrate 20 in order to stabilize the axially symmetric alignment by fixing the center of the axially symmetric alignment.
  • the alignment regulating structure for example, a protrusion 23 protruding toward the liquid crystal layer 30 as shown in FIG. 4A or an opening 21a formed in the counter electrode 21 as shown in FIG. 4B is used. be able to.
  • the liquid crystal display panel 100a further includes alignment maintaining layers 18 and 28 provided on the surfaces of the pair of vertical alignment films 16 and 26 on the liquid crystal layer 30 side.
  • the alignment maintaining layers 18 and 28 are formed from a photopolymerized product.
  • the alignment maintaining layers 18 and 28 define the pretilt direction of the liquid crystal molecules 31 when no voltage is applied to the liquid crystal layer 30. That is, when no voltage is applied to the liquid crystal layer 30, the liquid crystal molecules 31 in the vicinity of the alignment maintaining layers 18 and 28 are pretilted as shown in an enlarged manner in FIG.
  • the pretilt direction is represented by “pretilt azimuth” and “pretilt angle”.
  • the pretilt azimuth refers to a component in the plane of the liquid crystal layer 30 (in the substrate plane) among vectors indicating the alignment direction of the liquid crystal molecules 31 in the liquid crystal layer 30 to which no voltage is applied.
  • the pretilt angle is an angle (angle ⁇ in FIG. 2) formed by the long axis of the liquid crystal molecules 31 with respect to the substrate surface.
  • the angle (angle ⁇ in FIG. 2) formed by the major axis of the liquid crystal molecules 31 with respect to the normal direction of the substrate surface is referred to as “pre-tilt angle”.
  • the liquid crystal display device 100 is manufactured by the manufacturing method described below, thereby suppressing the display quality from being deteriorated due to the disorder of the tilt alignment.
  • a liquid crystal display panel 100a containing a photopolymerizable compound is prepared in the liquid crystal layer 30 (step (A)).
  • the photopolymerizable compound for example, materials disclosed in Patent Documents 3 and 4 can be used.
  • the active matrix substrate 10 and the counter substrate 20 can be manufactured and bonded together by various known methods for manufacturing a CPA mode liquid crystal display device.
  • the liquid crystal layer 30 is irradiated with light (ultraviolet rays UV) in a state where a potential difference is applied between the pixel electrode 11 and the counter electrode 21 of the liquid crystal display panel 100a.
  • the orientation maintaining layers 18 and 28 are formed by polymerizing the photopolymerizable compound in the layer 30 (step (B)).
  • This step (B) includes two steps (B-1) and (B-2) in which the potential difference applied between the pixel electrode 11 and the counter electrode 21 is different from each other.
  • these steps (B-1) and (B-2) will be described with reference to FIGS. 6 (a) and 6 (b).
  • FIG. 6A shows a change in potential difference applied between the pixel electrode 11 and the counter electrode 21 in the step (B) (that is, the steps (B-1) and (B-2)) (relationship between time and potential difference).
  • FIG. 6B is a graph showing a change in the pre-tilt angle defined by the orientation maintaining layers 18 and 28 in the step (B) (that is, the steps (B-1) and (B-2)) ( It is a graph which shows the relationship between time and a pre-fall angle.
  • step (B) step (B-1) is first executed.
  • a first potential difference (which is a potential difference smaller than a second potential difference described later and is an AC voltage of ⁇ 4 V in this case) is applied between the pixel electrode 11 and the counter electrode 21.
  • the liquid crystal layer 30 is irradiated with light.
  • This step (B-1) is performed until the pre-tilt angle reaches a predetermined magnitude or more (here, 0.7 °), more specifically, the pretilt defined by the alignment maintaining layers 18 and 28. This is performed until the orientation is substantially determined.
  • the step (B-1) is a step of substantially determining the pretilt azimuth defined by the alignment maintaining layers 18 and 28 while increasing the pre-tilt angle defined by the alignment maintaining layers 18 and 28.
  • the potential difference applied between the pixel electrode 11 and the counter electrode 21 in the step (B-1) is substantially constant (the first potential difference remains).
  • step (B-2) is executed.
  • step (B-2) light is applied to the liquid crystal layer 30 in a state where a second potential difference larger than the first potential difference (here, an AC voltage of ⁇ 10 V) is applied between the pixel electrode 11 and the counter electrode 21. Irradiate. Thereby, the pre-tilt angle defined by the alignment maintaining layers 18 and 28 further increases.
  • This step (B-2) is executed until the pre-tilt angle reaches a desired size (2.5 ° here).
  • the case where the potential difference applied between the pixel electrode 11 and the counter electrode 21 in the step (B-2) is substantially constant (the second potential difference remains unchanged) is exemplified.
  • the potential difference applied between the pixel electrode 11 and the counter electrode 21 is not necessarily constant. However, as will be described later, it is preferable that the potential difference in this step (B-2) be as large as possible without causing irreversible influence (failure or the like) on the liquid crystal display panel 100a.
  • step (B) including the steps (B-1) and (B-2) as described above, a step of providing a pair of polarizing plates outside the active matrix substrate 10 and the counter substrate 20 is performed. Thus, the liquid crystal display device 100 is obtained.
  • the PSA process includes two processes (B-1) and (B-1) in which the potential difference applied between the pixel electrode 11 and the counter electrode 21 is different. B-2), and the pre-tilt angle is increased by irradiating the liquid crystal layer 30 with light in a state where a relatively low first potential difference is applied between the pixel electrode 11 and the counter electrode 21.
  • the pretilt azimuth is substantially determined, and then the pretilt angle is further increased by irradiating the liquid crystal layer 30 with light with a relatively high second potential difference applied between the pixel electrode 11 and the counter electrode 21.
  • the deterioration of the display quality due to the disorder of the tilted orientation is suppressed because if the pre-tilt angle becomes a predetermined level or more, the potential difference between the pixel electrode 11 and the counter electrode 21 is changed thereafter. This is because the pretilt orientation does not substantially change. That is, after the pretilt azimuth is determined in a state where a relatively low first potential difference is applied between the pixel electrode 11 and the counter electrode 21 (that is, in a state in which the tilt alignment is not disturbed), the pixel electrode 11 is determined. By making the potential difference between the counter electrode 21 and the second potential difference relatively high, the processing tact time can be shortened and the risk of bubble failure can be reduced.
  • the manufacturing method according to the present embodiment is based on the new knowledge found by the present inventor that the pretilt azimuth does not substantially change after the pre-tilt angle is equal to or larger than a predetermined magnitude.
  • the PSA step (step (B)) By dividing the PSA step (step (B)) into a step (B-1) for substantially determining the pretilt direction and a step (B-2) for further increasing the pretilt angle thereafter, The liquid crystal display device 100 can be efficiently manufactured while suppressing the deterioration of display quality due to the disorder of the tilt alignment.
  • the conventional PSA process has been executed without changing the potential difference applied between the pixel electrode 11 and the counter electrode 21. This is because it was thought that it was necessary to keep the state of the tilted orientation constant in order to perform stable polymerization.
  • FIG. 7 shows an optical microscope image when the liquid crystal display device 100 according to the present embodiment is actually prototyped and observed in a state in which a voltage is applied to the liquid crystal layer 30 so that the liquid crystal molecules 31 are axially symmetrically aligned.
  • FIG. 8A shows an enlarged image of the vicinity of the region surrounded by the broken-line circle in FIG. 7, and FIG. 8B shows the liquid crystal molecules 31 in the portion shown in FIG. An orientation direction is shown typically.
  • the polarizing plate a pair of linear polarizing plates is provided, and as shown in FIG. 8A, these linear polarizing plates display one polarization axis (transmission axis) PA1. Parallel to the horizontal direction of the screen, the other polarization axis (transmission axis) PA2 is arranged in crossed Nicols so as to be parallel to the vertical direction of the display surface.
  • a nematic liquid crystal material having negative dielectric anisotropy (that is, negative type) is used as the liquid crystal material constituting the liquid crystal layer 30, and the vertical alignment films 16 and 26 are What was generally used in VA mode was used.
  • step (B-1) the voltage applied between the pixel electrode 11 and the counter electrode 21 is set to ⁇ 4 V, and the liquid crystal layer 30 is irradiated with ultraviolet rays having a wavelength of 313 nm or more for about 85 seconds.
  • the tilt angle was set to 0.7 ° or more.
  • step (B-2) the voltage applied between the pixel electrode 11 and the counter electrode 21 is set to ⁇ 8 V to ⁇ 12 V, and the liquid crystal layer 30 is irradiated with ultraviolet rays having a wavelength of 313 nm or more for about 30 seconds.
  • the pre-tilt angle was set to 2.0 ° to 4.0 °.
  • the liquid crystal molecules 31 of the liquid crystal layer 30 have a good axisymmetric orientation (the cross-shaped extinction pattern is either up, down, left, or right). Not deformed to be dragged to the side). Further, the state of axial symmetry alignment is almost uniform in all pixels.
  • FIGS. 9A to 9D show the alignment states immediately before the start of step (B-1), immediately after the end of step (B-1), immediately before the start of step (B-2), and immediately after the end of step (B-2). Show.
  • voltages applied between the pixel electrode 11 and the counter electrode 21 are ⁇ 4 V, ⁇ 4 V, ⁇ 10 V, and ⁇ 2.5 V, respectively.
  • FIGS. 27A and 27B show alignment states immediately before and immediately after the PSA process when the PSA process is performed in a state where a voltage of ⁇ 10 V is continuously applied between the pixel electrode and the counter electrode.
  • an orientation regulation region a portion surrounded by a broken circle in FIG. 27B
  • Axisymmetric orientation is disturbed.
  • the VA mode liquid crystal display device 100 to which the PSA technology is applied can be efficiently manufactured while suppressing deterioration in display quality due to disorder of tilted alignment. can do. That is, it is possible to achieve both the achievement of a good tilt orientation and the shortening of the PSA processing time (and shortening of the processing tact and the risk of occurrence of bubble defects). Therefore, mass production can be performed with high yield while improving the display quality of the liquid crystal display device 100. Further, it is possible to improve reliability while improving apparatus processing capability.
  • Table 1 below shows that in the PSA process, when the voltage between the pixel electrode and the counter electrode is high (eg, ⁇ 10 V) (Comparative Example 1), when the voltage is low (eg, ⁇ 4 V) (Comparative Example 2), low
  • the ultraviolet irradiation time in the PSA process, the apparatus processing capability, the alignment state in the voltage application state is good or bad, Display quality is good or bad.
  • the UV irradiation time in Comparative Example 1 is 60 to 80 seconds, while the UV irradiation time in Comparative Example 2 exceeds 300 seconds.
  • the ultraviolet irradiation time is 100 to 120 seconds, which is slightly longer than Comparative Example 1, but much shorter than Comparative Example 2. Therefore, in Comparative Example 2, the apparatus throughput is low, whereas in Comparative Example 1 and Example 1, the apparatus throughput is high.
  • Comparative Example 1 the alignment state in the voltage application state is not good (bad), whereas in Comparative Example 2 and Example 1, the alignment state in the voltage application state is good.
  • FIG. 10A shows an example of the alignment state in Comparative Example 1
  • FIG. 10B shows an example of the alignment state in Comparative Example 2 and Example 1.
  • Comparative Example 1 As shown in FIG. 10A, the liquid crystal molecules 31 are largely tilted in a specific direction (upper side in the illustrated example). Therefore, the orientation dependency of the viewing angle becomes large. On the other hand, in Comparative Example 2 and Example 1, as shown in FIG. 10B, the liquid crystal molecules 31 fall almost uniformly in all directions. Therefore, the orientation dependency of the viewing angle is small.
  • Comparative Example 2 and Example 1 have good display quality. This is because, as shown in FIG. 26A and FIG. 8A, the tilt alignment is not disturbed and the tilt alignment state is almost uniform in all pixels.
  • Comparative Example 2 and Example 1 have good display quality. This is because, as shown in FIG. 10B, the liquid crystal molecules 31 fall almost uniformly in all directions.
  • the “first potential difference” in the step (B-1) is not limited to the exemplified values.
  • the first potential difference is such that the symmetry of the tilt alignment of the liquid crystal molecules 31 in each pixel is substantially highest when the potential difference applied between the pixel electrode 11 and the counter electrode 21 is the first potential difference. It is preferable to set to. In order to set the first potential difference in this way, the following method can be used.
  • the potential difference that maximizes the symmetry of the extinction pattern with respect to the orientation center of the axially symmetric orientation is selected as the first potential difference. do it. More specifically, as shown in FIG. 11A, four virtual lines L1 parallel to the vertical direction, the horizontal direction, the upper right-lower left direction, and the upper left-lower right direction for a certain pixel of interest. , L2, L3, and L4, the potential difference between the pixel electrode 11 and the counter electrode 21 is changed, and the uniformity of the transmittance is the highest for each of these four lines (for example, FIG. 11 ( As shown in b), a voltage range in which one side and the other side are both extinguished or transmissive with respect to the center of orientation at the portion overlapping each line is determined, and the median is defined as the first potential difference. That's fine.
  • the “second potential difference” in the step (B-2) is not limited to the exemplified value.
  • the second potential difference is preferably as large as possible without causing irreversible influence (failure or the like) on the liquid crystal display panel 100a.
  • the second potential difference is preferably 1.2 times to 15 times the first potential difference. If the second potential difference exceeds 15 times the first potential difference, the liquid crystal display panel 100a may exceed a range that does not have an irreversible effect. Further, if the second potential difference is less than 1.2 times the first potential difference, the effect of shortening the time required for the PSA process may not be sufficiently obtained.
  • the step (B-1 ) In the step (B-2) is not less than ⁇ 2 V and not more than ⁇ 5 V, and the “second potential difference” in the step (B-2) is not less than ⁇ 3 V and not more than ⁇ 30 V.
  • pre-tilt angle immediately after executing the step (B-1) and the pre-tilt angle after executing the step (B-2) are not limited to the exemplified values.
  • the pre-tilt angle is preferably 0.7 ° or more.
  • the pre-tilt angle immediately after the execution of the step (B-1) is preferably 1.3 ° or less.
  • the pre-tilt angle after executing the step (B-2) is typically 1.5 ° to 5.0 °, and the pre-tilt angle after executing the step (B-2). Is typically not less than 1.2 times and not more than 7 times the pre-tilt angle immediately after execution of the step (B-1).
  • FIG. 12 is a plan view schematically showing a region corresponding to one pixel of the liquid crystal display device 100A.
  • FIG. 13 is a cross-sectional view taken along line 13A-13A ′ in FIG. 12, showing a state in which no voltage is applied to the liquid crystal layer 30 (a state in which a voltage less than the threshold voltage is applied). Yes.
  • the liquid crystal display device 100A is a VA mode liquid crystal display device including a pixel electrode 11A having a fine stripe pattern (referred to as “fishbone structure”). It is different from 100.
  • FIG. 12 and FIG. 13 components having the same functions as those of the liquid crystal display device 100 of Embodiment 1 are denoted by the same reference numerals, and description thereof will be omitted below (in subsequent drawings). Is the same).
  • the pixel electrode 11A of the liquid crystal display device 100A includes a cross-shaped trunk portion 11c, a plurality of branch portions 11d extending in a direction of approximately 45 ° from the trunk portion 11c, and a plurality of branch portions 11d.
  • the liquid crystal molecules 31 are inclined and aligned in a plurality of directions in each pixel. Specifically, in each pixel, the liquid crystal molecules 31 are inclined and aligned in four directions, and four (four types) liquid crystal domains are formed in the liquid crystal layer 30.
  • the trunk portion 11c of the pixel electrode 11A has a straight line portion (horizontal straight line portion) 11c1 extending in the horizontal direction and a straight line portion (vertical straight line portion) 11c2 extending in the vertical direction.
  • the horizontal straight line portion 11c1 and the vertical straight line portion 11c2 intersect (orthogonal) each other at the center of the pixel.
  • the plurality of branch portions 11d are divided into four groups corresponding to the four regions divided by the cross-shaped trunk portion 11c. Assuming that the display surface is a clock face, when the azimuth angle of 0 ° is 3 o'clock and the counterclockwise direction is positive, the plurality of branch portions 11d are composed of branch portions 11d1 extending in the direction of 45 ° azimuth. The first group, the second group composed of the branch portion 11d2 extending in the azimuth angle 135 ° direction, the third group composed of the branch portion 11d3 extending in the azimuth angle 225 ° direction, and the branch portion 11d4 extending in the azimuth angle 315 ° direction. Divided into a fourth group.
  • the width L of each of the plurality of branch portions 11d and the interval S between the adjacent branch portions 11d are typically 1.5 ⁇ m or more and 5 0.0 ⁇ m or less. From the viewpoint of alignment stability and luminance of the liquid crystal molecules 31, the width L and the spacing S of the branch portions 11d are preferably within the above ranges.
  • the number of branch portions 11d extending from the horizontal straight portion 11c1 of the trunk portion 11c and the number of branch portions 11d extending from the vertical straight portion 11c2 are not limited to those illustrated in FIGS.
  • Each of the plurality of slits 11e extends in the same direction as the adjacent branch portion 11d. Specifically, the slit 11e between the first group of branch portions 11d1 extends in the azimuth angle 45 ° direction, and the slit 11e between the second group of branch portions 11d2 extends in the azimuth angle 135 ° direction. Further, the slit 11e between the third group branch portions 11d3 extends in the azimuth angle 225 ° direction, and the slit 11e between the fourth group branch portions 11d4 extends in the azimuth angle 315 ° direction.
  • the direction in which the liquid crystal molecules 31 tilt is defined by the oblique electric field generated in each slit (that is, the portion where the conductive film of the pixel electrode 11A does not exist) 11e.
  • This orientation is parallel to the branch portion 11d (that is, parallel to the slit 11e) and is directed to the trunk portion 11c (that is, an orientation different from the extending orientation of the branch portion 11d by 180 °).
  • the azimuth angle of the tilt azimuth (first azimuth: arrow A) defined by the first group of branches 11d1 is about 225 °
  • the tilt azimuth defined by the second group of branches 11d2 ( The azimuth angle of the second azimuth: arrow B) is about 315 °
  • the azimuth angle of the tilt azimuth (third azimuth: arrow C) defined by the third group of branches 11d3 is about 45 °
  • the azimuth angle of the tilt azimuth (fourth azimuth: arrow D) defined by the group branch 11d4 is about 135 °.
  • the four directions A to D are directions of directors of the respective liquid crystal domains in the 4D structure formed when a voltage is applied.
  • the directions A to D are substantially parallel to any one of the plurality of branch portions 11d and form an angle of about 45 ° with the polarization axis of a pair of polarizing plates (not shown). Further, the difference between any two orientations of the orientations A to D is substantially equal to an integral multiple of 90 °, and the orientations of the directors of the liquid crystal domains adjacent to each other through the trunk portion 11c (eg, orientation A and orientation B) are substantially 90 °. Different.
  • the fishbone structure of the pixel electrode 11A is not limited to that illustrated in FIG. 12 and the like, and a known fishbone structure can be used as appropriate.
  • the pixel electrode 11A may have two or more trunk portions 11c.
  • Pixel electrodes having a fishbone structure are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2003-149647, 2006-78968, and 2003-177418.
  • the pixel electrode 11A has a fishbone structure, so that a plurality of liquid crystal domains are formed in each pixel when a voltage is applied.
  • the liquid crystal display panel 100a includes the alignment maintaining layer 18 and the alignment maintaining layer 18 provided on the surfaces of the pair of vertical alignment films 16 and 26 on the liquid crystal layer 30 side, as shown in FIG. 28.
  • liquid crystal display device that includes a pixel electrode having a fishbone structure and to which the PSA technology is applied, a high voltage is applied to the liquid crystal layer during the PSA process in order to shorten the PSA process.
  • liquid crystal molecules liquid crystal molecules denoted by reference numeral 31 'in FIG. 14
  • the display quality is deteriorated. I understood.
  • the PSA process in manufacturing the liquid crystal display device 100A is performed in two stages (two processes (B-1) and (B-1) in which the potential difference applied between the pixel electrode 11A and the counter electrode 21 is different from each other).
  • B-2 two processes in which the potential difference applied between the pixel electrode 11A and the counter electrode 21 is different from each other.
  • Table 2 below shows that in the PSA process, when the voltage between the pixel electrode and the counter electrode is a high voltage (for example, ⁇ 10 V) (Comparative Example 3), and from a low voltage to a high voltage (for example, ⁇ 8 V to ⁇ 10 V) 2
  • a high voltage for example, ⁇ 10 V
  • a low voltage for example, ⁇ 8 V to ⁇ 10 V
  • the ultraviolet irradiation time is 60 to 80 seconds in Comparative Example 3, and the ultraviolet irradiation time is 60 to 80 seconds in Example 1. Therefore, the apparatus processing capability is increased in Comparative Example 3 and Example 2.
  • FIG. 15A shows an example of the alignment state in Comparative Example 3
  • FIG. 15B shows an example of the alignment state in Example 2.
  • Comparative Example 3 As shown in FIG. 15 (a), there are liquid crystal molecules 31 that fall in an orientation deviated from desired orientations A to D. On the other hand, in Example 2, as shown in FIG. 15B, the liquid crystal molecules 31 are almost tilted in the desired directions A to D.
  • Example 2 the display quality is good. This is because the tilt alignment is not disturbed and the tilt alignment state is almost uniform in all pixels.
  • Example 2 the display quality is good. This is because, as shown in FIG. 15B, the liquid crystal molecules 31 are almost tilted in the desired directions A to D.
  • the PSA step (step (B)) is divided into a step (B-1) for substantially determining the pretilt direction and a step (B-2) for further increasing the pretilt angle thereafter.
  • the VA mode liquid crystal display device 100A to which the PSA technology is applied can be efficiently manufactured while suppressing the deterioration of the display quality due to the disorder of the tilt alignment. That is, it is possible to achieve both the achievement of a good tilt orientation and the shortening of the PSA processing time (and shortening of the processing tact and the risk of occurrence of bubble defects). Therefore, mass production can be performed with a high yield while improving the display quality of the liquid crystal display device 100A. Further, it is possible to improve reliability while improving apparatus processing capability.
  • FIG. 16 shows a liquid crystal display device 100B in the present embodiment.
  • FIG. 16 is a cross-sectional view schematically showing the liquid crystal display device 100B, and shows a state where no voltage is applied to the liquid crystal layer 30 (a state where a voltage lower than the threshold voltage is applied).
  • the pair of vertical alignment films 16L and 26L are photo-alignment films that have been subjected to photo-alignment processing.
  • the pretilt direction defined by one of the pair of photo-alignment films 16L and 26L and the pretilt direction defined by the other differ from each other by approximately 90 °, and the tilt direction ( Reference orientation direction) is defined.
  • the liquid crystal molecules 31 take a twist alignment according to the alignment regulating force of the photo-alignment films 16L and 26L.
  • the VA mode in which the liquid crystal molecules 31 are twisted is It is sometimes called a VATN (Vertical / Alignment / Twisted / Nematic) mode or an RTN (Reverse / Twisted / Nematic) mode.
  • VATN Vertical / Alignment / Twisted / Nematic
  • RTN Reverse / Twisted / Nematic
  • the RTN mode in which the 4D structure is formed may be referred to as a 4D-RTN mode.
  • the pixel electrode 11B of the liquid crystal display device 100B may be a so-called solid electrode in which notches and slits are not formed.
  • FIG. 17 shows a substantially square pixel region P corresponding to a substantially square pixel electrode.
  • the present invention is not limited to the shape of the pixel region.
  • the pixel region P may be substantially rectangular.
  • the pixel region P has four liquid crystal domains LD1, LD2, LD3, and LD4.
  • the respective tilt directions (reference alignment directions) of the liquid crystal domains LD1, LD2, LD3, and LD4 are t1, t2, t3, and t4
  • the difference between any two directions is approximately equal to an integral multiple of 90 ° 4
  • the areas of the liquid crystal domains LD1, LD2, LD3, and LD4 are equal to each other, and the example shown in FIG. 17 is an example of the most preferable quadrant structure in view angle characteristics.
  • the four liquid crystal domains LD1, LD2, LD3, and LD4 are arranged in a matrix of 2 rows and 2 columns.
  • the pair of polarizing plates that face each other with the liquid crystal layer 30 interposed therebetween are arranged so that the transmission axes (polarization axes) are substantially orthogonal to each other.
  • the transmission axis is arranged substantially parallel to the horizontal direction of the display surface, and the other transmission axis is arranged substantially parallel to the vertical direction of the display surface.
  • the arrangement of the transmission axes of the polarizing plates is the same.
  • the tilt direction t1 of the liquid crystal domain LD1 is approximately 225 °
  • the tilt direction t2 of the liquid crystal domain LD2 is approximately 315 °
  • the tilt direction t3 of the liquid crystal domain LD3 is approximately 45 °
  • the tilt direction t4 of the liquid crystal domain LD4 is approximately 135 °. That is, the liquid crystal domains LD1, LD2, LD3, and LD4 are arranged such that their tilt directions differ by approximately 90 ° between adjacent liquid crystal domains.
  • FIGS. 18A, 18B, and 18C are diagrams for explaining a method of dividing the pixel region P1 shown in FIG. 18A shows the pretilt directions PA1 and PA2 defined by the photo-alignment film 16L provided on the active matrix substrate (first substrate) 10, and FIG. 18B shows the counter substrate (second substrate). )
  • the pretilt directions PB1 and PB2 defined by the photo-alignment film 26L provided at 20 are shown.
  • FIG. 18C shows the tilt direction when a voltage is applied to the liquid crystal layer 20.
  • the orientation direction of the liquid crystal molecules 31 when viewed from the observer side is schematically shown, and the end portion (elliptical portion) of the liquid crystal molecules 31 shown in a columnar shape is drawn. It shows that the liquid crystal molecules 31 are tilted so as to be closer to the observer.
  • the area on the active matrix substrate 10 side (area corresponding to one pixel area P) is vertically divided into two parts, and the respective areas (upper area and lower area) are divided.
  • Alignment processing is performed so that pretilt directions PA1 and PA2 antiparallel to the vertical alignment film 16L are provided.
  • the photo-alignment process is performed by obliquely irradiating polarized ultraviolet rays from the direction indicated by the arrow.
  • the region on the counter substrate 20 side (region corresponding to one pixel region P) is divided into two parts on the left and right, and the vertical alignment of each region (left region and right region).
  • Orientation treatment is performed so that pretilt directions PB1 and PB2 antiparallel to the film 26L are provided.
  • the photo-alignment process is performed by obliquely irradiating polarized ultraviolet rays from the direction indicated by the arrow.
  • the pretilt direction defined by the photo-alignment film 16L on the active matrix substrate 10 side and the photo-alignment film 26L on the counter substrate 20 side are defined.
  • the pretilt direction differs from the pretilt direction by approximately 90 °, and the tilt direction (reference alignment direction) is defined in the middle of the two pretilt directions.
  • the liquid crystal display panel 100B has alignment maintaining layers 18 and 28 as shown in FIG.
  • a method for manufacturing the liquid crystal display device 100B according to the present embodiment will be described with reference to FIGS. 19 (a) and 19 (b).
  • a liquid crystal display panel 100a containing a photopolymerizable compound is prepared in the liquid crystal layer 30 (step (A)).
  • the liquid crystal layer 30 is irradiated with light (ultraviolet UV) in a state where a potential difference is applied between the pixel electrode 11B and the counter electrode 21 of the liquid crystal display panel 100a.
  • the orientation maintaining layers 18 and 28 are formed by polymerizing the photopolymerizable compound in the layer 30 (step (B)).
  • the step (A) is different from each other in the photo-alignment film 16L (typically anti-parallel) by irradiating one of the pair of photo-alignment films 16L and 26L with light.
  • (A-2) forming a plurality of regions defining the pretilt direction.
  • the active matrix substrate 10 and the counter substrate 20 are bonded to each other through a sealant, and then the sealant is cured by heating.
  • A-3 is further included.
  • steps (A-1) and (A-2) are executed such that the pre-tilt angle defined by the pair of photo-alignment films 16L and 26L is a predetermined magnitude or more. .
  • the pretilt orientation defined by the alignment sustaining layers 18 and 28 is substantially determined.
  • the pretilt direction is defined by the photo-alignment film
  • reliability pre-tilt angle retention
  • burn-in in which the pre-tilt angle varies in a display pattern that always lights up is a problem.
  • the effect of the photo-alignment treatment is achieved by the heat treatment (for example, about 120 ° C.) in the sealant curing step (step (A-3)) performed after the photo-alignment treatment (steps (A-1) and (A-2)). It may become thin and a desired pre-tilt angle may not be obtained, or an orientation failure may occur.
  • the problem as described above can be solved by performing the PSA process (execution of the step (B)) after the step (A) as in the present embodiment.
  • the steps (A-1) and (A-2) are performed so that the pre-tilt angle defined by the pair of photo-alignment films 16L and 26L is equal to or greater than a predetermined magnitude, whereby the alignment maintaining layer 18 By substantially determining the pretilt azimuth defined by and 28, the occurrence of the above-described problem can be prevented more reliably.
  • the steps (A-1) and (A-2) are preferably performed so that the pre-tilt angle defined by the pair of photo-alignment films 16L and 26L is 2 ° or more.
  • regulated by the orientation maintenance layers 18 and 28 can be determined more reliably.
  • the pre-tilt angle is reduced by the heat treatment in the step (A-3), but the pre-tilt angle defined by the pair of photo-alignment films 16L and 26L immediately after the execution of the step (A-3) is 0.7. If it is at least 0 °, the pretilt direction defined by the alignment maintaining layers 18 and 28 can be determined more reliably.
  • the pre-tilt angle immediately after executing the step (A-3) is about 1 °.
  • the pre-tilt angle defined by the alignment maintaining layers 18 and 28 is about 2.5 ° to 4 °. Therefore, sufficient alignment regulation can be performed.
  • a manufacturing method capable of efficiently manufacturing a VA mode liquid crystal display device to which the PSA technology is applied while suppressing deterioration in display quality due to disorder of tilt alignment.
  • Active matrix substrate DESCRIPTION OF SYMBOLS 10a Transparent substrate 11, 11A, 11B Pixel electrode 11a Sub pixel electrode 11b Notch part 11c Trunk part 11d Branch part 11e Slit 12 Scan wiring 13 Signal wiring 14 Auxiliary capacity wiring 15 Interlayer insulation layer 16 Vertical alignment film 16L Photo-alignment film (Vertical alignment film) film) 18 Orientation maintenance layer 20 Counter substrate (second substrate) 20a transparent substrate 21 counter electrode 21a opening 22 color filter layer 23 convex part 26 vertical alignment film 26L photo-alignment film (vertical alignment film) 28 orientation maintaining layer 30 liquid crystal layer 31 liquid crystal molecule 100a liquid crystal display panel 100, 100A, 100B liquid crystal display device

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Abstract

Selon la présente invention, un procédé de fabrication d'un dispositif d'affichage à cristaux liquides (100) comprend les éléments suivants : une étape (A) pour préparer un panneau d'affichage à cristaux liquides (100a) qui comporte un composé de photopolymérisation dans une couche de cristaux liquides (30) ; et une étape (B) pour former des couches de maintien de l'orientation (18, 28) en émettant de la lumière sur la couche de cristaux liquides de manière à polymériser le composé de photopolymérisation, et pour le faire au moment où une différence de potentiel est appliquée entre une électrode de pixel (11) et une contre-électrode (21). L'étape (B) comporte les étapes suivantes : une étape (B-1) lors de laquelle, à cause de l'émission de lumière sur la couche de cristaux liquides au moment où une première différence de potentiel est appliquée entre l'électrode de pixel et la contre-électrode, l'angle d'inclinaison préalable stipulé par les couches de maintien de l'orientation est augmenté, et l'orientation d'inclinaison préalable stipulée par les couches de maintien de l'orientation est efficacement établie ; et une étape (B-2), qui suit l'étape (B-1) et dans laquelle, à cause de l'émission de lumière sur la couche de cristaux liquides au moment où une seconde différence de potentiel supérieure à la première différence de potentiel est appliquée entre l'électrode de pixel et la contre-électrode, l'angle d'inclinaison préalable est encore augmenté.
PCT/JP2014/064586 2013-06-07 2014-06-02 Procédé de fabrication d'un dispositif d'affichage à cristaux liquides WO2014196495A1 (fr)

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JP2013-120918 2013-06-07
JP2013120918 2013-06-07

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WO2010116565A1 (fr) * 2009-04-08 2010-10-14 シャープ株式会社 Dispositif d'affichage à cristaux liquides, procédé pour fabriquer un dispositif d'affichage à cristaux liquides, composition pour la formation d'un film photopolymère, et composition pour la formation d'une couche de cristaux liquides

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JP2008158186A (ja) * 2006-12-22 2008-07-10 Sony Corp 液晶表示装置の製造方法
US20090213320A1 (en) * 2008-02-22 2009-08-27 Samsung Electronics Co., Ltd. Method of manufacturing liquid crystal display
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WO2010116565A1 (fr) * 2009-04-08 2010-10-14 シャープ株式会社 Dispositif d'affichage à cristaux liquides, procédé pour fabriquer un dispositif d'affichage à cristaux liquides, composition pour la formation d'un film photopolymère, et composition pour la formation d'une couche de cristaux liquides

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113671757A (zh) * 2021-08-31 2021-11-19 深圳市华星光电半导体显示技术有限公司 液晶显示面板及其制作方法
CN113671757B (zh) * 2021-08-31 2024-02-02 深圳市华星光电半导体显示技术有限公司 液晶显示面板及其制作方法

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