WO2014196495A1 - Manufacturing method for liquid crystal display device - Google Patents

Manufacturing method for liquid crystal display device 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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WIPO (PCT)
Prior art keywords
liquid crystal
crystal display
alignment
crystal layer
display device
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PCT/JP2014/064586
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French (fr)
Japanese (ja)
Inventor
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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Publication of WO2014196495A1 publication Critical patent/WO2014196495A1/en

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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

In the present invention, a manufacturing method for a liquid crystal display device (100) comprises the following: a step (A) for preparing a liquid crystal display panel (100a) that includes a photopolymerization compound in a liquid crystal layer (30); and a step (B) for forming orientation maintaining layers (18, 28) by emitting light onto the liquid crystal layer so as to polymerize the photopolymerization compound, and to do so in a state where a potential difference is imparted between a pixel electrode (11) and a counter electrode (21). The step (B) includes the following: a step (B-1) in which due to the emission of light onto the liquid crystal layer in a state where a first potential difference is imparted between the pixel electrode and the counter electrode, a pre-slant angle stipulated by the orientation maintaining layers is increased, and a pre-tilt orientation stipulated by the orientation maintaining layers is effectively established; and a step (B-2), following the step (B-1), in which due to the emission of light onto the liquid crystal layer in a state where a second potential difference larger than the first potential difference is imparted between the pixel electrode and the counter electrode, the pre-slant angle is further increased.

Description

液晶表示装置の製造方法Manufacturing method of liquid crystal display device
　本発明は、液晶表示装置の製造方法に関し、特に、配向維持層を有する液晶表示装置の製造方法に関する。 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.
　近年、広視野角特性を有する液晶表示装置が開発され、パーソナルコンピュータのモニタや携帯情報端末機器の表示装置、あるいは、テレビジョン受像機として広く利用されている。 Recently, a 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.
　広視野角を実現するための表示モードの１つとして、垂直配向型の液晶層を用いた表示モード（「ＶＡモード」と呼ばれる。）が知られている。本出願人は、特許文献１に、ＶＡモードの液晶表示装置の一種を開示している。この液晶表示装置においては、電圧印加時に画素内で複数の液晶ドメインが形成され、それぞれの液晶ドメイン内で液晶分子は放射状に傾斜配向する（つまり軸対称配向をとる）。特許文献１に開示されている特徴的な配向状態を用いる表示モードは、ＣＰＡ（Continuous Pinwheel Alignment）モードと呼ばれる。 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. The present applicant discloses a kind of VA mode liquid crystal display device in Patent Document 1. In this liquid crystal display device, 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モードでは、画素電極を切欠き部や開口部によって複数のサブ画素電極（特許文献１では「単位中実部」と呼ばれている。）に分割し、電圧印加時にサブ画素電極のエッジ部に生成される斜め電界を用いて、軸対称配向を形成する。特許文献２には、軸対称配向を安定にするために、対向基板の液晶層側に配向規制構造を設けた構成が提案されている。特許文献２には、配向規制構造として、液晶層側に突き出た凸部や対向電極に形成された開口部が記載されている。 In the CPA mode, 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.
　一方、ＶＡモードの配向安定性や応答速度を向上させるための技術として、ＰＳＡ技術（Polymer Sustained Alignment Technology）が提案されている（例えば特許文献３および４）。ＰＳＡ技術では、配向膜上に形成された光重合物によって、液晶分子のプレチルト方向が制御される。光重合物は、液晶材料中に少量の光重合性化合物（例えば光重合性モノマー）を混入しておき、液晶セルを組み立てた後、液晶層に所定の電圧を印加した状態で光重合性化合物に紫外線を照射することによって形成される。光重合物が形成されるときの液晶分子の配向状態が、電圧を取り去った後（電圧を印加しない状態）においても光重合物によって維持（記憶）されるので、配向安定性や応答速度が向上する。この光重合物から構成される層を、本願明細書では配向維持層（Alignment Sustaining Layer）と呼ぶ。また、電圧印加状態で液晶層に光（紫外線）を照射することによって配向維持層を形成する処理（工程）を、本願明細書ではＰＳＡ処理（工程）と呼ぶ。 On the other hand, PSA technology (Polymer Sustained Alignment Technology) has been proposed as a technology for improving the alignment stability and response speed of the VA mode (for example, Patent Documents 3 and 4). In the PSA technique, 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. To do. The layer composed of the photopolymerized product is referred to as an alignment maintaining layer (Alignment Sustaining Layer) in the present specification. Further, 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.
　特許文献５には、ＰＳＡ技術が適用されたＣＰＡモードの液晶表示装置が開示されている。図２０および図２１に、特許文献５に開示されている液晶表示装置８００を示す。図２０は、液晶表示装置８００の１つの画素に対応した領域を模式的に示す平面図である。図２１は、図２０中の２１Ａ－２１Ａ’線に沿った断面図であり、液晶層に電圧が印加されていない状態（しきい値電圧未満の電圧が印加されている状態）を示している。 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). .
　液晶表示装置８００は、液晶表示パネル８００ａを備え、マトリクス状に配列された複数の画素を有している。液晶表示パネル８００ａは、アクティブマトリクス基板８１０と、アクティブマトリクス基板８１０に対向する対向基板８２０と、アクティブマトリクス基板８１０と対向基板８２０との間に設けられた垂直配向型の液晶層８３０とを含んでいる。 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.
　アクティブマトリクス基板８１０は、透明基板８１０ａと、透明基板８１０ａ上に設けられた画素電極８１１とを有する。アクティブマトリクス基板８１０は、さらに、画素電極８１１に電気的に接続されたＴＦＴ（不図示）と、スイッチング素子であるＴＦＴに信号を供給する配線を含む配線群とを有する。配線群は、具体的には、ＴＦＴに走査信号を供給する走査配線８１２やＴＦＴに映像信号を供給する信号配線８１３、補助容量を形成するための補助容量配線８１４を含んでいる。画素電極８１１は、複数の画素のそれぞれに配置されており、配線群やＴＦＴを覆う層間絶縁膜８１５上に形成されている。 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. Specifically, 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.
　対向基板８２０は、透明基板８２０ａと、透明基板８２０ａ上に設けられた対向電極８２１とを有する。本実施形態では、透明基板８２０ａと対向電極８２１との間には、カラーフィルタ層８２２が設けられている。画素電極８１１が複数の画素のそれぞれに配置されているのに対し、対向電極８２１は、典型的には、すべての画素電極８１１に対向する１つの透明導電膜として形成される。 The counter substrate 820 includes a transparent substrate 820a and a counter electrode 821 provided on the transparent substrate 820a. In the present embodiment, a color filter layer 822 is provided between the transparent substrate 820a and the counter electrode 821. While 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.
　アクティブマトリクス基板８１０および対向基板８２０の液晶層８３０側の表面には、垂直配向膜（不図示）が設けられている。また、典型的には、アクティブマトリクス基板８１０および対向基板８２０の外側に、クロスニコルに配置された一対の偏光板が設けられる。 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. In addition, typically, a pair of polarizing plates arranged in a crossed Nicol state is provided outside the active matrix substrate 810 and the counter substrate 820.
　液晶層８３０は、負の誘電異方性を有する液晶分子８３１を含む。液晶層８３０内の液晶分子８３１は、液晶層８３０に電圧が印加されていないときに、垂直配向膜の表面に対してほぼ垂直に配向する。 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.
　液晶表示装置８００の画素電極８１１は、複数のサブ画素電極８１１ａを有している。 The pixel electrode 811 of the liquid crystal display device 800 has a plurality of sub-pixel electrodes 811a.
　図２２および図２３に、画素電極８１１と対向電極８２１との間に所定の電圧（しきい値電圧以上の電圧）が印加されたときの液晶分子８３１の配向状態を示す。画素電極８１１と対向電極８２１との間に所定の電圧が印加されると、図２２および図２３に示すように、各サブ画素電極８１１ａ上に液晶ドメインが形成される。液晶ドメイン内で液晶分子８３１は軸対称に傾斜した配向をとる。 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. When a predetermined voltage is applied between the pixel electrode 811 and the counter electrode 821, a liquid crystal domain is formed on each sub-pixel electrode 811a as shown in FIGS. Within the liquid crystal domain, the liquid crystal molecules 831 have an axially tilted orientation.
　サブ画素電極８１１ａごとに、軸対称配向をとる液晶ドメインが形成されるのは、サブ画素電極８１１ａが独立した島に近い外縁を有し、このサブ画素電極８１１ａのエッジ部に生成される斜め電界の配向規制力が液晶分子８３１に作用するからである。サブ画素電極８１１ａのエッジ部に生成される電界は、サブ画素電極８１１ａの中心に向かって傾斜し、液晶分子８３１を軸対称に配向させるように作用する。 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.
　液晶表示装置８００の画素電極８１１は、図２０などに示すように、複数のサブ画素電極８１１ａのそれぞれの略中心に形成された開口部８１１ｂを有している。また、複数のサブ画素電極８１１ａのそれぞれのエッジ部は、配線群、すなわち、走査配線８１２や信号配線８１３、補助容量配線８１４に重なっている。 As shown in FIG. 20 and the like, 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. In addition, 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.
　さらに、液晶表示装置８００の液晶層８３０は、図２１に模式的に示しているように、液晶分子８３１の配向方向を規定するための配向維持層（ポリマー構造物）８３２を含んでいる。配向維持層８３２は、液晶層８３０を構成する液晶材料に光重合性化合物を予め混入しておき、液晶層８３２に電圧が印加された状態でこの光重合性化合物を重合することによって垂直配向膜上に形成される。配向維持層８３２が形成されるときの液晶分子８３１の配向状態が、電圧を取り去った後（電圧を印加しない状態）においても維持（記憶）されるので、配向安定性や応答速度が向上する。 Furthermore, 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.
特開２００３－４３５２５号公報JP 2003-43525 A 特開２００２－２０２５１１号公報JP 2002-202511 A 特開２００２－３５７８３０号公報JP 2002-357830 A 特開２００３－３０７７２０号公報JP 2003-307720 A 特開２００８－２４２０３６号公報JP 2008-242036 A
　しかしながら、特許文献５に開示されているような、ＰＳＡ技術が適用されたＣＰＡモードの液晶表示装置８００では、画素内で所望の軸対称配向が得られないこと、あるいは、画素間で軸対称配向の状態が異なることに起因した表示品位の低下が発生することがある。具体的には、表示がざらついたり、視角によって色味が変わったりすることがある。 However, in the CPA mode liquid crystal display device 800 to which the PSA technology is applied as disclosed in Patent Document 5, a desired axially symmetric alignment cannot be obtained within a pixel, or an axially symmetric alignment between pixels. The display quality may be deteriorated due to the different states. Specifically, the display may be rough or the color may change depending on the viewing angle.
　図２４に、特許文献５の液晶表示装置８００を実際に試作し、液晶分子８３１が軸対称配向するように液晶層８３０に電圧を印加した状態で観察を行ったときの光学顕微鏡像を示す。また、図２５（ａ）に、図２４中の破線の円で囲まれた領域付近を拡大した像を示し、図２５（ｂ）に、図２５（ａ）に示した部分における液晶分子８３１の配向方向を模式的に示す。ここで、偏光板としては、一対の直線偏光板が設けられており、これらの直線偏光板は、図２５（ａ）に示されているように、一方の偏光軸（透過軸）ＰＡ１が表示面の水平方向に平行に、他方の偏光軸（透過軸）ＰＡ２が表示面の垂直方向に平行になるように、クロスニコルに配置されている。 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. Here, as 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.
　図２４、図２５（ａ）および（ｂ）から、液晶分子８３１の配向の対称性が崩れており（十字状の消光模様が下側に引きずられるように変形している）、所望の軸対称配向が得られていないことがわかる。また、画素間で軸対称配向の状態が異なっていることもわかる。 24, 25 (a) and 25 (b), 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.
　上述したように、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置では、傾斜配向の乱れに起因した表示品位の低下が発生することがある。 As described above, in the VA mode liquid crystal display device to which the PSA technology is applied, the display quality may be deteriorated due to the disorder of the tilt alignment.
　本発明は、上記問題に鑑みてなされたものであり、その目的は、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置を、傾斜配向の乱れに起因した表示品位の低下を抑制しつつ、効率良く製造し得る製造方法を提供することにある。 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.
　本発明の実施形態における液晶表示装置の製造方法は、第１基板と、第２基板と、前記第１基板および前記第２基板の間に設けられた垂直配向型の液晶層とを有する液晶表示パネルを備え、マトリクス状に配列された複数の画素を有し、前記第１基板は、前記複数の画素のそれぞれに設けられた画素電極を有し、前記第２基板は、前記画素電極に対向する対向電極を有し、前記液晶層に所定の電圧が印加されたときに、前記複数の画素のそれぞれ内において、前記液晶層の液晶分子が複数の方位に傾斜配向し、前記液晶表示パネルは、前記画素電極および前記液晶層の間と前記対向電極および前記液晶層の間とに設けられた一対の垂直配向膜と、前記一対の垂直配向膜のそれぞれの前記液晶層側の表面に光重合物から形成された配向維持層であって、前記液晶層に電圧が印加されていないときに前記液晶分子のプレチルト方位およびプレ倒れ角を規定する配向維持層と、をさらに有する液晶表示装置の製造方法であって、前記液晶層中に光重合性化合物を含む前記液晶表示パネルを用意する工程（Ａ）と、前記液晶表示パネルの前記画素電極および前記対向電極の間に電位差が与えられた状態で、前記液晶層に光を照射して前記液晶層中の光重合性化合物を重合することによって、前記配向維持層を形成する工程（Ｂ）と、を包含し、前記工程（Ｂ）は、前記画素電極および前記対向電極の間に第１の電位差が与えられた状態で前記液晶層に光を照射することによって、前記配向維持層によって規定されるプレ倒れ角を増加させつつ、前記配向維持層によって規定されるプレチルト方位を実質的に確定させる工程（Ｂ－１）と、前記工程（Ｂ－１）の後に、前記画素電極および前記対向電極の間に前記第１の電位差よりも大きな第２の電位差が与えられた状態で前記液晶層に光を照射することによって、前記プレ倒れ角をさらに増加させる工程（Ｂ－２）と、を含む。 A method for manufacturing a liquid crystal display device according to an embodiment of the present invention includes a first substrate, a second substrate, and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate. A plurality of pixels arranged in a matrix, wherein the first substrate has a pixel electrode provided on each of the plurality of pixels, and the second substrate is opposed to the pixel electrode; When a predetermined voltage is applied to the liquid crystal layer, 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 liquid crystal display device comprising: A step (A) of preparing the liquid crystal display panel containing a photopolymerizable compound on the surface, and irradiating the liquid crystal layer with light in a state where a potential difference is applied between the pixel electrode and the counter electrode of the liquid crystal display panel. And (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.
　ある実施形態において、前記第１の電位差は、前記複数の画素のそれぞれ内における前記液晶分子の傾斜配向の対称性が、前記画素電極および前記対向電極の間に与えられる電位差を前記第１の電位差としたときに実質的にもっとも高くなるように設定される。 In one embodiment, 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.
　ある実施形態において、前記第２の電位差は、前記第１の電位差の１．２倍以上１５倍以下である。 In one embodiment, the second potential difference is not less than 1.2 times and not more than 15 times the first potential difference.
　ある実施形態において、前記工程（Ｂ－２）を実行した後の前記プレ倒れ角は、前記工程（Ｂ－１）を実行した直後の前記プレ倒れ角の１．２倍以上６倍以下である。 In one embodiment, 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). .
　ある実施形態において、前記工程（Ｂ－１）を実行した直後の前記プレ倒れ角は０．７°以上である。 In one embodiment, the pre-tilt angle immediately after performing the step (B-1) is 0.7 ° or more.
　ある実施形態において、前記液晶層に所定の電圧が印加されたときに、前記複数の画素のそれぞれ内において、前記液晶分子は軸対称配向をとる。 In one embodiment, 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.
　ある実施形態において、前記画素電極は、少なくとも１つの十字形状の幹部と、前記少なくとも１つの十字形状の幹部から略４５°方向に延びる複数の枝部と、前記複数の枝部間に形成された複数のスリットと、を有する。 In one embodiment, 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.
　本発明の実施形態における他の液晶表示装置の製造方法は、第１基板と、第２基板と、前記第１基板および前記第２基板の間に設けられた垂直配向型の液晶層とを有する液晶表示パネルを備え、マトリクス状に配列された複数の画素を有し、前記第１基板は、前記複数の画素のそれぞれに設けられた画素電極を有し、前記第２基板は、前記画素電極に対向する対向電極を有し、前記液晶層に所定の電圧が印加されたときに、前記複数の画素のそれぞれ内において、前記液晶層の液晶分子が複数の方位に傾斜配向し、前記液晶表示パネルは、前記画素電極および前記液晶層の間と前記対向電極および前記液晶層の間とに設けられた一対の垂直配向膜と、前記一対の垂直配向膜のそれぞれの前記液晶層側の表面に光重合物から形成された配向維持層であって、前記液晶層に電圧が印加されていないときに前記液晶分子のプレチルト方位およびプレ倒れ角を規定する配向維持層と、をさらに有し、前記一対の垂直配向膜は、一対の光配向膜である液晶表示装置の製造方法であって、前記液晶層中に光重合性化合物を含む前記液晶表示パネルを用意する工程（Ａ）と、前記液晶表示パネルの前記画素電極および前記対向電極の間に電位差が与えられた状態で、前記液晶層に光を照射して前記液晶層中の光重合性化合物を重合することによって、前記配向維持層を形成する工程（Ｂ）と、を包含し、前記工程（Ａ）は、前記一対の光配向膜のうちの一方の光配向膜に光を照射することによって、前記一方の光配向膜に、互いに異なるプレチルト方向を規定する複数の領域を形成する工程（Ａ－１）と、前記一対の光配向膜のうちの他方の光配向膜に光を照射することによって、前記他方の光配向膜に、互いに異なるプレチルト方向を規定する複数の領域を形成する工程（Ａ－２）と、を含み、前記工程（Ａ－１）および（Ａ－２）は、前記一対の光配向膜によって規定されるプレ倒れ角が所定の大きさ以上になるように実行され、そのことにより、前記配向維持層によって規定されるプレチルト方位が実質的に確定される。 Another method of manufacturing a liquid crystal display device according to an embodiment of the present invention 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. Oriented fibers formed from photopolymers 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. And 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 | direction prescribed | regulated by the said orientation maintenance layer is substantially decided.
　ある実施形態において、前記工程（Ａ－１）および（Ａ－２）は、前記一対の光配向膜によって規定されるプレ倒れ角が２°以上になるように実行される。 In one embodiment, 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.
　ある実施形態において、前記工程（Ａ）は、前記工程（Ａ－１）および（Ａ－２）の後に、前記第１基板と前記第２基板とをシール剤を介して互いに貼り合わせ、その後、加熱によって前記シール剤を硬化する工程（Ａ－３）をさらに含む。 In one embodiment, in the step (A), after the steps (A-1) and (A-2), 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.
　ある実施形態において、前記工程（Ａ－３）を実行した直後の前記一対の光配向膜によって規定されるプレ倒れ角は０．７°以上である。 In one embodiment, a pre-tilt angle defined by the pair of photo-alignment films immediately after performing the step (A-3) is 0.7 ° or more.
　本発明の実施形態によれば、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置を、傾斜配向の乱れに起因した表示品位の低下を抑制しつつ、効率良く製造し得る製造方法が提供される。 According to the embodiments of the present invention, there is provided 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. .
本発明の実施形態における液晶表示装置１００の１つの画素に対応した領域を模式的に示す平面図である。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. 液晶表示装置１００を模式的に示す図であり、図１中の２Ａ－２Ａ’線に沿った断面図である。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）は、液晶表示装置１００の１つの画素に対応した領域を模式的に示す平面図であり、液晶層３０に所定の電圧が印加された状態を示しており、（ｂ）は、（ａ）中の３Ｂ－３Ｂ’線に沿った断面図である。(A) is a top view which shows typically the area | region corresponding to one pixel of the liquid crystal display device 100, and has shown the state in which the predetermined voltage was applied to the liquid crystal layer 30, (b), It is sectional drawing along the 3B-3B 'line in a). （ａ）は、配向規制構造として用いられる凸部２３を示す図であり、（ｂ）は、配向規制構造として用いられる開口部２１ａを示す図である。(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. （ａ）および（ｂ）は、液晶表示装置１００の製造方法を説明するための工程断面図である。(A) And (b) is process sectional drawing for demonstrating the manufacturing method of the liquid crystal display device 100. FIG. （ａ）は、工程（Ｂ－１）および（Ｂ－２）における、画素電極１１および対向電極２１の間に与えられる電位差の変化（時間と電位差の関係）を示すグラフであり、（ｂ）は、工程（Ｂ－１）および（Ｂ－２）における、配向維持層１８および２８によって規定されるプレ倒れ角の変化（時間とプレ倒れ角の関係）を示すグラフである。(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). 液晶表示装置１００を実際に試作し、液晶分子３１が軸対称配向するように液晶層３０に電圧を印加した状態で観察を行ったときの光学顕微鏡像である。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）は、図７中の破線の円で囲まれた領域付近を拡大した図であり、（ｂ）は、（ａ）に示した部分における液晶分子３１の配向方向を模式的に示す図である。(A) is the figure which expanded the area | region vicinity enclosed with the broken-line circle | round | yen in FIG. 7, (b) is a figure which shows typically the orientation direction of the liquid crystal molecule 31 in the part shown to (a). It is. （ａ）～（ｄ）は、工程（Ｂ－１）開始直前、工程（Ｂ－１）終了直後、工程（Ｂ－２）開始直前および工程（Ｂ－２）終了直後の配向状態を示す図（光学顕微鏡像）である。(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). （ａ）は、比較例１における配向状態の例を示す図であり、（ｂ）は、比較例２および実施例１における配向状態の例を示す図である。(A) 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. （ａ）および（ｂ）は、工程（Ｂ－１）おいて画素電極１１と対向電極２１との間に与えられる電位差の最適値を求める方法を説明するための図である。(A) And (b) is a figure for demonstrating the method of calculating | requiring the optimal value of the electrical potential difference given between the pixel electrode 11 and the counter electrode 21 in process (B-1). 本発明の実施形態における液晶表示装置１００Ａの１つの画素に対応した領域を模式的に示す平面図である。It is a top view which shows typically the area | region corresponding to one pixel of 100 A of liquid crystal display devices in embodiment of this invention. 液晶表示装置１００Ａを模式的に示す図であり、図１２中の１３Ａ－１３Ａ’線に沿った断面図である。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. 液晶表示装置１００Ａが備える画素電極１１Ａの具体的な構造と、各液晶ドメインのディレクタの方位との関係を説明するための図である。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. （ａ）は、比較例３における配向状態の例を示す図であり、（ｂ）は、実施例２における配向状態の例を示す図である。(A) is a figure which shows the example of the orientation state in the comparative example 3, (b) is a figure which shows the example of the orientation state in Example 2. FIG. 本発明の実施形態における液晶表示装置１００Ｂを模式的に示す断面図である。It is sectional drawing which shows typically the liquid crystal display device 100B in embodiment of this invention. 液晶表示装置１００Ｂにおける配向分割構造を有する画素領域Ｐを示す図である。It is a figure which shows the pixel area P which has the alignment division | segmentation structure in the liquid crystal display device 100B. 図１７に示した画素領域Ｐの分割方法を説明するための図であり、（ａ）はアクティブマトリクス基板１０側のプレチルト方向を示し、（ｂ）は対向基板２０側のプレチルト方向を示し、（ｃ）は液晶層３０に電圧を印加したときのチルト方向を示している。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. （ａ）および（ｂ）は、液晶表示装置１００Ｂの製造方法を説明するための工程断面図である。(A) And (b) is process sectional drawing for demonstrating the manufacturing method of liquid crystal display device 100B. 特許文献５に開示されている液晶表示装置８００の１つの画素に対応した領域を模式的に示す平面図である。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. 液晶表示装置８００を模式的に示す図であり、図２０中の２１Ａ－２１Ａ’線に沿った断面図である。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. 液晶表示装置８００の１つの画素に対応した領域を模式的に示す平面図であり、液晶層８３０に所定の電圧が印加された状態を示している。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. 液晶表示装置８００を模式的に示す図であり、図２２中の２３Ａ－２３Ａ’線に沿った断面図である。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. 特許文献５の液晶表示装置８００を実際に試作し、液晶分子８３１が軸対称配向するように液晶層８３０に電圧を印加した状態で観察を行ったときの光学顕微鏡像である。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）は、図２４中の破線の円で囲まれた領域付近を拡大した図であり、（ｂ）は、（ａ）に示した部分における液晶分子８３１の配向方向を模式的に示す図である。(A) is the figure which expanded the area | region vicinity enclosed with the broken-line circle | round | yen in FIG. 24, (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）は、ＰＳＡ処理の際に液晶層に±４Ｖの電圧を印加した場合の傾斜配向の状態を示す図であり、（ｂ）は、ＰＳＡ処理の際に液晶層に±１０Ｖの電圧を印加した場合の傾斜配向の状態を示す図である。(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. It is a figure which shows the state of the inclination orientation at the time of applying. （ａ）および（ｂ）は、画素電極と対向電極との間に±１０Ｖの電圧をずっと印加した状態でＰＳＡ処理を行う場合の、ＰＳＡ処理直前およびＰＳＡ処理直後の配向状態を示す図である。(A) And (b) is a figure which shows the orientation state immediately before PSA processing and immediately after PSA processing in the case of performing PSA processing in a state where a voltage of ± 10 V is continuously applied between the pixel electrode and the counter electrode. .
　本願発明者は、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置において、傾斜配向の乱れが発生する理由を検討した結果、以下の知見を得た。 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.
　ＰＳＡ処理の際の傾斜配向の状態は、画素電極と対向電極との間の電位差（つまり液晶層に印加されている電圧）の大きさによって変わる。従来は、ＰＳＡ処理の際に液晶層に高電圧が印加されることによって傾斜配向に乱れが発生し、その状態で配向維持層が形成されることにより、上述したような表示品位の低下が発生していたと思われる。ＰＳＡ処理の際に高電圧の印加が行われていたのは、処理タクトの短時間化のためと、紫外線の照射による気泡不良（材料の分解によって発生するガスに起因する）の発生リスクを低減させるためである。 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). Conventionally, 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.
　図２６（ａ）に、ＰＳＡ処理の際に液晶層に±４Ｖの電圧を印加した場合の傾斜配向の状態を示す。また、図２６（ｂ）に、ＰＳＡ処理の際に液晶層に±１０Ｖの電圧を印加した場合の傾斜配向の状態を示す。 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.
　図２６（ａ）と図２６（ｂ）との比較からわかるように、液晶層に低電圧を印加した場合には、液晶層に高電圧を印加した場合よりも、傾斜配向の状態が良好であることがわかる。ただし、液晶層に低電圧を印加した場合には、紫外線の照射を長時間行う必要があるので、処理タクトが長時間化するとともに、気泡不良の発生リスクが増加してしまう。一方、液晶層に高電圧を印加した場合には、処理タクトの短時間化および気泡不良の発生リスクの低減を実現できるものの、傾斜配向が乱れてしまう。 As can be seen from the comparison between FIG. 26A and FIG. 26B, when the low voltage is applied to the liquid crystal layer, the tilted alignment state is better than when the high voltage is applied to the liquid crystal layer. I know that there is. However, when a low voltage is applied to the liquid crystal layer, it is necessary to irradiate ultraviolet rays for a long time, so that the processing tact time becomes longer and the risk of bubble defects increases. On the other hand, when a high voltage is applied to the liquid crystal layer, the processing time can be shortened and the risk of bubble defects can be reduced, but the tilt alignment is disturbed.
　上述したように、従来の製造方法では、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置を、傾斜配向の乱れに起因した表示品位の低下を抑制しつつ、効率良く製造することはできなかった。 As described above, 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. .
　以下、図面を参照しながら本発明の実施形態を説明する。なお、本発明は以下の実施形態に限定されるものではない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.
　（実施形態１）
　図１および図２に、本実施形態における液晶表示装置１００を示す。図１は、液晶表示装置１００の１つの画素に対応した領域を模式的に示す平面図である。図２は、図１中の２Ａ－２Ａ’線に沿った断面図であり、液晶層３０に電圧が印加されていない状態（しきい値電圧未満の電圧が印加されている状態）を示している。 (Embodiment 1)
1 and 2 show a liquid crystal display device 100 according to this embodiment. 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.
　液晶表示装置１００は、液晶表示パネル１００ａを備え、マトリクス状に配列された複数の画素を有する。液晶表示パネル１００ａは、アクティブマトリクス基板（第１基板）１０と、アクティブマトリクス基板１０に対向する対向基板（第２基板）２０と、アクティブマトリクス基板１０および対向基板２０の間に設けられた垂直配向型の液晶層３０とを有する。 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.
　アクティブマトリクス基板１０は、透明基板（例えばガラス基板）１０ａと、透明基板１０ａ上に設けられた画素電極１１とを有する。アクティブマトリクス基板１１は、さらに、画素電極１１に電気的に接続されたＴＦＴ（不図示）と、スイッチング素子であるＴＦＴに信号を供給する配線を含む配線群とを有する。配線群は、具体的には、ＴＦＴに走査信号を供給する走査配線１２やＴＦＴに映像信号を供給する信号配線１３、補助容量を構成する一対の電極の一方に所定の電圧（Ｃｓ電圧）を供給するための補助容量配線１４を含んでいる。画素電極１１は、複数の画素のそれぞれに設けられており、配線群やＴＦＴを覆う層間絶縁膜１５上に形成されている。 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. Specifically, 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.
　対向基板２０は、透明基板２０ａ（例えばガラス基板）と、透明基板２０ａ上に設けられ、画素電極１１に対向する対向電極２１とを有する。本実施形態では、透明基板２０ａと対向電極２１との間には、カラーフィルタ層２２が設けられている。画素電極１１が複数の画素のそれぞれに設けられているのに対し、対向電極２１は、典型的には、すべての画素電極１１に対向する１つの透明導電膜として形成される。 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. In the present embodiment, a color filter layer 22 is provided between the transparent substrate 20 a and the counter electrode 21. While 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.
　画素電極１１と液晶層３０との間には、垂直配向膜１６が形成されている。また、対向電極２１と液晶層３０との間にも、垂直配向膜２６が形成されている。つまり、液晶表示パネル１００ａには、一対の垂直配向膜１６および２６が設けられている。 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.
　液晶層３０は、負の誘電異方性を有する液晶分子３１を含み、必要に応じてさらにカイラル剤を含んでいる。液晶層３０内の液晶分子３１は、液晶層３０に電圧が印加されていないときに、垂直配向膜１６および２６の表面に対してほぼ垂直に配向する。 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.
　ここでは図示しないが、液晶層３０を介して互いに対向するように、一対の偏光板が設けられている。一対の偏光板のそれぞれは、直線偏光板であってもよいし、円偏光板であってもよい。 Although not shown here, 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.
　液晶表示装置１００の画素電極１１は、複数のサブ画素電極１１ａを有している。より具体的には、画素電極１１は、２つの切欠き部（スリット）１１ｂによって２つのサブ画素電極１１ａに分割されている。なお、ここでは、２つのサブ画素電極１１ａを有する画素電極１１を例示しているが、画素電極１１は３つ以上のサブ画素電極１１ａを含んでもよい。また、本実施形態では、各サブ画素電極１１ａは円弧状の角部を有する略矩形状であるが、サブ画素電極１１ａの形状はこれに限定されるものではない。サブ画素電極１１ａは、例えば、矩形状や円形状であってもよい。 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. Here, the pixel electrode 11 having two subpixel electrodes 11a is illustrated, but the pixel electrode 11 may include three or more subpixel electrodes 11a. In the present embodiment, 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.
　図３（ａ）および（ｂ）に、液晶層３０に所定の電圧（しきい値電圧以上の電圧）が印加されたときの液晶分子３１の配向状態を示す。液晶層３０に所定の電圧が印加されると、各画素内において、液晶分子３１が複数の方位に傾斜配向する。より具体的には、図３（ａ）および（ｂ）に示すように、各サブ画素電極１１ａ上に液晶ドメインが形成され、液晶ドメイン内で液晶分子３１は軸対称に傾斜した配向（軸対称配向、あるいは、放射状傾斜配向と呼ばれる）をとる。 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. FIG. 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).
　サブ画素電極１１ａごとに、軸対称配向の液晶ドメインが形成されるのは、サブ画素電極１１ａが独立した島に近い外縁を有し、このサブ画素電極１１ａのエッジ部に生成される斜め電界の配向規制力が液晶分子３１に作用するからである。サブ画素電極１１ａのエッジ部に生成される電界は、サブ画素電極１１ａの中心に向かって傾斜し、液晶分子３１を軸対称に配向させるように作用する。 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.
　なお、軸対称配向の中心を固定して軸対称配向をより安定化するために、対向基板２０の液晶層３０側に配向規制構造を設けることが好ましい。配向規制構造としては、例えば、図４（ａ）に示すような液晶層３０側に突き出た凸部２３や、図４（ｂ）に示すような対向電極２１に形成された開口部２１ａを用いることができる。 Note that it is preferable to provide 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. As 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.
　また、液晶表示パネル１００ａは、一対の垂直配向膜１６および２６のそれぞれの液晶層３０側の表面に設けられた配向維持層１８および２８をさらに有する。配向維持層１８および２８は、光重合物から形成されている。配向維持層１８および２８は、液晶層３０に電圧が印加されていないときに液晶分子３１のプレチルト方向を規定する。つまり、液晶層３０に電圧が印加されていないときに、配向維持層１８および２８近傍の液晶分子３１は、図２中に拡大して示しているように、プレチルトしている。 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.
　プレチルト方向は、「プレチルト方位」と「プレチルト角」とによって表される。プレチルト方位は、電圧が印加されていない液晶層３０内の液晶分子３１の配向方向を示すベクトルの内、液晶層３０面内（基板面内）における成分を指す。プレチルト角は、液晶分子３１の長軸が基板面に対してなす角（図２中の角α）である。 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 α in FIG. 2) formed by the long axis of the liquid crystal molecules 31 with respect to the substrate surface.
　また、本願明細書では、液晶分子３１の長軸が基板面法線方向に対してなす角（図２中の角θ）を、「プレ倒れ角」と呼ぶ。プレ倒れ角は、９０°からプレチルト角を減じた値である（つまりθ＝９０°－α）。従って、配向維持層１８および２８は、液晶層３０に電圧が印加されていないときに液晶分子３１のプレチルト方位およびプレ倒れ角を規定するともいえる。 In the present specification, the angle (angle θ 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 pre-tilt angle is a value obtained by subtracting the pre-tilt angle from 90 ° (that is, θ = 90 ° −α). Therefore, it can be said that the alignment maintaining layers 18 and 28 define the pretilt azimuth and the pretilt angle of the liquid crystal molecules 31 when no voltage is applied to the liquid crystal layer 30.
　上述したような配向維持層１８および２８が設けられていることにより、安定な軸対称配向を実現することができ、応答特性が向上する。また、本実施形態における液晶表示装置１００は、以下に説明する製造方法によって製造されることにより、傾斜配向の乱れに起因した表示品位の低下が抑制される。 By providing the alignment maintaining layers 18 and 28 as described above, stable axially symmetric alignment can be realized, and response characteristics are improved. In addition, the liquid crystal display device 100 according to the present embodiment is manufactured by the manufacturing method described below, thereby suppressing the display quality from being deteriorated due to the disorder of the tilt alignment.
　続いて、図５（ａ）および（ｂ）を参照しながら、本実施形態における液晶表示装置１００の製造方法を説明する。 Subsequently, a method for manufacturing the liquid crystal display device 100 according to the present embodiment will be described with reference to FIGS. 5 (a) and 5 (b).
　まず、図５（ａ）に示すように、液晶層３０中に光重合性化合物を含む液晶表示パネル１００ａを用意する（工程（Ａ））。光重合性化合物としては、例えば、特許文献３および４に開示されているような材料を用いることができる。アクティブマトリクス基板１０および対向基板２０の作製やこれらの貼り合わせ等は、ＣＰＡモードの液晶表示装置を製造するための公知の種々の方法によって行うことができる。 First, as shown in FIG. 5A, a liquid crystal display panel 100a containing a photopolymerizable compound is prepared in the liquid crystal layer 30 (step (A)). As 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.
　次に、図５（ｂ）に示すように、液晶表示パネル１００ａの画素電極１１および対向電極２１の間に電位差が与えられた状態で、液晶層３０に光（紫外線ＵＶ）を照射して液晶層３０中の光重合性化合物を重合することによって、配向維持層１８および２８を形成する（工程（Ｂ））。この工程（Ｂ）（ＰＳＡ工程）は、画素電極１１および対向電極２１の間に与えられる電位差が互いに異なる２つの工程（Ｂ－１）および（Ｂ－２）を含む。以下、図６（ａ）および（ｂ）を参照しながら、これらの工程（Ｂ－１）および（Ｂ－２）を説明する。図６（ａ）は、工程（Ｂ）（つまり工程（Ｂ－１）および（Ｂ－２））における、画素電極１１および対向電極２１の間に与えられる電位差の変化（時間と電位差の関係）を示すグラフであり、図６（ｂ）は、工程（Ｂ）（つまり工程（Ｂ－１）および（Ｂ－２））における、配向維持層１８および２８によって規定されるプレ倒れ角の変化（時間とプレ倒れ角の関係）を示すグラフである。 Next, as shown in FIG. 5B, 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) (PSA step) 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. Hereinafter, 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.
　工程（Ｂ）において、まず、工程（Ｂ－１）が実行される。工程（Ｂ－１）では、画素電極１１および対向電極２１の間に第１の電位差（後述する第２の電位差よりも小さな電位差であり、ここでは±４Ｖの交流電圧）が与えられた状態で液晶層３０に光を照射する。これにより、配向維持層１８および２８によって規定されるプレ倒れ角が増加していく。この工程（Ｂ－１）は、プレ倒れ角が所定の大きさ以上になるまで（ここでは０．７°になるまで）、より具体的には、配向維持層１８および２８によって規定されるプレチルト方位が実質的に確定されるまで実行される。つまり、工程（Ｂ－１）は、配向維持層１８および２８によって規定されるプレ倒れ角を増加させつつ、配向維持層１８および２８によって規定されるプレチルト方位を実質的に確定させる工程である。本実施形態では、工程（Ｂ－１）において画素電極１１および対向電極２１の間に与えられる電位差は、実質的に一定（第１の電位差のまま）である。 In step (B), step (B-1) is first executed. In the step (B-1), 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. As a result, the pre-tilt angle defined by the alignment maintaining layers 18 and 28 increases. 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. That is, 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. In the present embodiment, 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).
　工程（Ｂ－１）の後に、工程（Ｂ－２）が実行される。工程（Ｂ－２）では、画素電極１１および対向電極２１の間に第１の電位差よりも大きな第２の電位差（ここでは±１０Ｖの交流電圧）が与えられた状態で液晶層３０に光を照射する。これにより、配向維持層１８および２８によって規定されるプレ倒れ角がさらに増加していく。この工程（Ｂ－２）は、プレ倒れ角が所望の大きさ（ここでは２．５°）になるまで実行される。なお、本実施形態では、工程（Ｂ－２）において画素電極１１および対向電極２１の間に与えられる電位差が、実質的に一定（第２の電位差のまま）である場合を例示しているが、この工程（Ｂ－２）において画素電極１１および対向電極２１の間に与えられる電位差は、必ずしも一定である必要はない。ただし、後述するように、この工程（Ｂ－２）における電位差は、液晶表示パネル１００ａに不可逆的な影響（故障等）を与えない範囲でなるべく大きいことが好ましい。 After step (B-1), step (B-2) is executed. In 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). In the present embodiment, 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. In this step (B-2), 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.
　上述したようにして工程（Ｂ－１）および（Ｂ－２）を含む工程（Ｂ）を実行した後、アクティブマトリクス基板１０および対向基板２０の外側に一対の偏光板を設ける工程などを行うことにより、液晶表示装置１００が得られる。 After performing the 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.
　上述したように、本実施形態の製造方法によれば、ＰＳＡ工程（工程（Ｂ））が、画素電極１１および対向電極２１の間に与えられる電位差が異なる２つの工程（Ｂ－１）および（Ｂ－２）を含んでおり、相対的に低い第１の電位差が画素電極１１および対向電極２１の間に与えられた状態で液晶層３０に光を照射することによってプレ倒れ角を増加させつつプレチルト方位を実質的に確定させ、その後、相対的に高い第２の電位差が画素電極１１および対向電極２１の間に与えられた状態で液晶層３０に光を照射することによってプレチルト角をさらに増加させる。このような製造方法を用いることにより、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置１００を、傾斜配向の乱れに起因した表示品位の低下を抑制しつつ、効率良く製造することができる。 As described above, according to the manufacturing method of the present embodiment, the PSA process (process (B)) 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. Let By using such a manufacturing method, it is possible to efficiently manufacture the VA mode liquid crystal display device 100 to which the PSA technique is applied while suppressing the deterioration of display quality due to the disorder of the tilt alignment.
　傾斜配向の乱れに起因した表示品位の低下が抑制されるのは、プレ倒れ角が所定の大きさ以上になれば、その後は、画素電極１１および対向電極２１の間の電位差を変化させても、プレチルト方位が実質的に変化しないからである。つまり、相対的に低い第１の電位差が画素電極１１および対向電極２１の間に印加されている状態（つまり傾斜配向に乱れが生じていない状態）でプレチルト方位を確定させてから、画素電極１１および対向電極２１の間の電位差を相対的に高い第２の電位差とすることにより、処理タクトの短時間化および気泡不良の発生リスクの低減を実現できる。 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.
　このように、本実施形態の製造方法は、いったんプレ倒れ角が所定の大きさ以上になれば、その後は、プレチルト方位が実質的に変化しないという、本願発明者が見出した新たな知見に基づくものであり、ＰＳＡ工程（工程（Ｂ））を、プレチルト方位を実質的に確定させる工程（Ｂ－１）と、その後にプレチルト角をさらに増加させる工程（Ｂ－２）とに分けることにより、傾斜配向の乱れに起因した表示品位の低下を抑制しつつ、液晶表示装置１００を効率良く製造することができる。 As described above, 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. 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.
　従来のＰＳＡ工程は、画素電極１１および対向電極２１の間に与えられる電位差を変えずに実行されていた。これは、安定したポリマー化を行うためには、傾斜配向の状態を一定に保つことが必要であると考えられていたためである。 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.
　図７に、本実施形態における液晶表示装置１００を実際に試作し、液晶分子３１が軸対称配向するように液晶層３０に電圧を印加した状態で観察を行ったときの光学顕微鏡像を示す。また、図８（ａ）に、図７中の破線の円で囲まれた領域付近を拡大した像を示し、図８（ｂ）に、図８（ａ）に示した部分における液晶分子３１の配向方向を模式的に示す。ここで、偏光板としては、一対の直線偏光板が設けられており、これらの直線偏光板は、図８（ａ）に示されているように、一方の偏光軸（透過軸）ＰＡ１が表示面の水平方向に平行に、他方の偏光軸（透過軸）ＰＡ２が表示面の垂直方向に平行になるように、クロスニコルに配置されている。 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. Here, as 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.
　なお、液晶表示装置１００の試作に際しては、液晶層３０を構成する液晶材料として、負の誘電異方性を有する（つまりネガ型の）ネマチック液晶材料を用い、垂直配向膜１６および２６としては、ＶＡモードで一般的に用いられているものを用いた。 In the trial production of the liquid crystal display device 100, 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.
　また、工程（Ｂ－１）においては、画素電極１１および対向電極２１の間に印加される電圧を±４Ｖに設定し、液晶層３０に波長３１３ｎｍ以上の紫外線を８５秒程度照射して、プレ倒れ角を０．７°以上とした。工程（Ｂ－２）においては、画素電極１１および対向電極２１の間に印加される電圧を±８Ｖ～±１２Ｖに設定し、液晶層３０に波長３１３ｎｍ以上の紫外線を３０秒程度照射して、プレ倒れ角を２．０°～４．０°とした。 In 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. In the 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 °.
　図７、図８（ａ）および（ｂ）からわかるように、各画素において、液晶層３０の液晶分子３１が良好な軸対称配向をとっている（十字状の消光模様が上下左右のいずれか側に引きずられるように変形していない）。また、すべての画素で軸対称配向の状態がほぼ均一である。 As can be seen from FIGS. 7, 8A, and 8B, in each pixel, 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.
　図９（ａ）～（ｄ）に、工程（Ｂ－１）開始直前、工程（Ｂ－１）終了直後、工程（Ｂ－２）開始直前および工程（Ｂ－２）終了直後の配向状態を示す。図９（ａ）～（ｄ）に示す状態において、画素電極１１および対向電極２１の間に印加される電圧は、それぞれ±４Ｖ、±４Ｖ、±１０Ｖ、±２．５Ｖである。 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. In the states shown in FIGS. 9A to 9D, voltages applied between the pixel electrode 11 and the counter electrode 21 are ± 4 V, ± 4 V, ± 10 V, and ± 2.5 V, respectively.
　図９（ａ）～（ｄ）に示されているいずれの状態においても、軸対称配向に乱れは発生しておらず、軸対称配向の対称性はほぼ同じであるといえる。このことから、工程（Ｂ－１）においてプレ倒れ角が所定の大きさ以上になれば、その後は、画素電極１１および対向電極２１の間の電位差を変化させても、プレチルト方位が実質的に変化しないことがわかる。 In any of the states shown in FIGS. 9A to 9D, no disturbance occurs in the axially symmetric orientation, and it can be said that the symmetry of the axially symmetric orientation is almost the same. From this, if the pre-tilt angle becomes greater than or equal to a predetermined magnitude in the step (B-1), then the pretilt azimuth is substantially reduced even if the potential difference between the pixel electrode 11 and the counter electrode 21 is changed. It turns out that it does not change.
　これに対し、従来のＰＳＡ処理を行う場合には、処理タクトを短時間化するためには、画素電極と対向電極との間に印加される電圧を高くする必要があるので、傾斜配向が乱れた状態で配向維持層を形成することになる。図２７（ａ）および（ｂ）に、画素電極と対向電極との間に±１０Ｖの電圧をずっと印加した状態でＰＳＡ処理を行う場合の、ＰＳＡ処理直前およびＰＳＡ処理直後の配向状態を示す。図２７（ａ）および（ｂ）からわかるように、ＰＳＡ処理直後には、意図しないところに配向規制領域（図２７（ｂ）中の破線の円で囲まれた部分）が形成されてしまい、軸対称配向が乱れてしまっている。 On the other hand, when the conventional PSA process is performed, in order to shorten the processing tact time, it is necessary to increase the voltage applied between the pixel electrode and the counter electrode. In this state, the orientation maintaining layer is formed. 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. As can be seen from FIGS. 27A and 27B, immediately after the PSA process, an orientation regulation region (a portion surrounded by a broken circle in FIG. 27B) is formed in an unintended place. Axisymmetric orientation is disturbed.
　上述したように、本実施形態の製造方法を用いることにより、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置１００を、傾斜配向の乱れに起因した表示品位の低下を抑制しつつ、効率良く製造することができる。つまり、良好な傾斜配向の実現と、ＰＳＡ処理時間の短時間化（およびそれによる処理タクトの短縮、気泡不良の発生リスクの低減）とを両立することができる。そのため、液晶表示装置１００の表示品位を向上させつつ、高い歩留りで量産を行うことができる。また、装置処理能力を向上させつつ、信頼性を向上させることができる。 As described above, by using the manufacturing method of the present embodiment, 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.
　下記表１に、ＰＳＡ処理において、画素電極－対向電極間電圧が高電圧（例えば±１０Ｖ）である場合（比較例１）、低電圧（例えば±４Ｖ）である場合（比較例２）、低電圧から高電圧へと（例えば±４Ｖから±１０Ｖ）２ステップに変化する場合（実施例１）について、ＰＳＡ処理における紫外線照射時間、装置処理能力の高低、電圧印加状態における配向状態の良し悪し、表示品位の良し悪しを示す。 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 In the case of changing from voltage to high voltage (for example, ± 4 V to ± 10 V) in two steps (Example 1), 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.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示されているように、比較例１では紫外線照射時間が６０～８０秒であるのに対し、比較例２では紫外線照射時間は３００秒を超えてしまう。実施例１では、紫外線照射時間は１００～１２０秒であり、比較例１よりはやや長いものの、比較例２に比べるとずっと短い。そのため、比較例２では装置処理能力が低くなるのに対し、比較例１および実施例１では装置処理能力が高くなる。 As shown in Table 1, 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. In Example 1, 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.
　また、比較例１では、電圧印加状態における配向状態が良好ではない（悪い）のに対し、比較例２および実施例１では、電圧印加状態における配向状態は良好である。図１０（ａ）に、比較例１における配向状態の例を示し、図１０（ｂ）に、比較例２および実施例１における配向状態の例を示す。 In 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, and FIG. 10B shows an example of the alignment state in Comparative Example 2 and Example 1.
　比較例１では、図１０（ａ）に示すように、液晶分子３１は特定の方位（図示している例では上側）に多く倒れる。従って、視野角の方位依存性が大きくなってしまう。これに対し、比較例２および実施例１では、図１０（ｂ）に示すように、液晶分子３１はすべての方位にほぼ均等に倒れる。従って、視野角の方位依存性が小さい。 In 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.
　また、表示光として直線偏光を用いる場合（つまり一対の偏光板が直線偏光板である場合）、比較例１では表示品位が悪い。これは、図２６（ｂ）に示したように、傾斜配向が乱れており、また、その程度が画素間で異なっているからである。 Further, when linearly polarized light is used as the display light (that is, when the pair of polarizing plates are linearly polarizing plates), the display quality is poor in Comparative Example 1. This is because, as shown in FIG. 26B, the tilted orientation is disturbed, and the degree differs between pixels.
　これに対し、比較例２および実施例１では表示品位が良好である。これは、図２６（ａ）や図８（ａ）に示したように、傾斜配向の乱れが発生せず、すべての画素で傾斜配向の状態がほぼ均一だからである。 In contrast, 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.
　また、表示光として円偏光を用いる場合（つまり一対の偏光板が円偏光板である場合）でも、比較例１では表示品位が悪い。これは、図１０（ａ）に示したような液晶分子３１の倒れ方が、画素あるいは色ごとに異なるため、表示がざらついたり、視角によって色味が変わったりすることがあるからである。 Even when circularly polarized light is used as the display light (that is, when the pair of polarizing plates is a circularly polarizing plate), the display quality in Comparative Example 1 is poor. This is because the manner in which the liquid crystal molecules 31 are tilted as shown in FIG. 10A differs for each pixel or color, so that the display may be rough or the color may change depending on the viewing angle.
　これに対し、比較例２および実施例１では表示品位は良好である。これは、図１０（ｂ）に示したように、液晶分子３１がすべての方位にほぼ均等に倒れるからである。 In contrast, 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.
　なお、工程（Ｂ－１）における「第１の電位差」は、例示した値に限定されない。第１の電位差は、各画素内における液晶分子３１の傾斜配向の対称性が、画素電極１１および対向電極２１の間に与えられる電位差を第１の電位差としたときに実質的にもっとも高くなるように設定されることが好ましい。第１の電位差をこのように設定するためには、以下のような手法を用いることができる。 Note that 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.
　例えば、軸対称配向の配向中心（上述した凸部や対向電極２１の開口部を設ける場合にはそれらに重なる）に対する消光模様の対称性が最も高くなるような電位差を、第１の電位差として選択すればよい。より具体的には、着目したある画素に対し、図１１（ａ）に示すように、上下方向、左右方向、右上－左下方向、左上－右下方向に平行な４本の仮想的な線Ｌ１、Ｌ２、Ｌ３およびＬ４を引いた上で、画素電極１１と対向電極２１との間の電位差を変化させ、これら４本の線のそれぞれについて透過率の均一性がもっとも高くなる（例えば図１１（ｂ）に示すように、各線に重なっている部分について配向中心を境として一方側と他方側とがともに消光状態または透過状態となる）電圧範囲を求め、その中央値を第１の電位差とすればよい。 For example, the potential difference that maximizes the symmetry of the extinction pattern with respect to the orientation center of the axially symmetric orientation (overlaps with the above-described convex portion and the opening of the counter electrode 21) 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.
　また、工程（Ｂ－２）における「第２の電位差」も、例示した値に限定されない。第２の電位差は、液晶表示パネル１００ａに不可逆的な影響（故障等）を与えない範囲でなるべく大きいことが好ましい。具体的には、第２の電位差は、第１の電位差の１．２倍以上１５倍以下であることが好ましい。第２の電位差が第１の電位差の１５倍を超えると、液晶表示パネル１００ａに不可逆的な影響を与えない範囲を超えるおそれがある。また、第２の電位差が第１の電位差の１．２倍未満であると、ＰＳＡ処理に要する時間の短縮効果を十分に得られないおそれがある。 Further, 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. Specifically, 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.
　液晶表示パネル１００ａの材料として、一般的なＣＰＡモード用の材料（液晶材料、配向膜材料）および一般的なＰＳＡ処理用の光重合性化合物を用いる場合、典型的には、工程（Ｂ－１）における「第１の電位差」は±２Ｖ以上±５Ｖ以下であり、工程（Ｂ－２）における「第２の電位差」は±３Ｖ以上±３０Ｖ以下である。 In the case of using a general CPA mode material (liquid crystal material, alignment film material) and a general PSA processing photopolymerizable compound as the material of the liquid crystal display panel 100a, typically, 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.
　また、工程（Ｂ－１）を実行した直後のプレ倒れ角および工程（Ｂ－２）を実行した後のプレ倒れ角も、例示した値に限定されるものではない。 Further, the 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.
　液晶表示パネル１００ａの材料として、一般的なＣＰＡモード用の材料（液晶材料、配向膜材料）および一般的なＰＳＡ処理用の光重合性化合物を用いる場合、工程（Ｂ－１）を実行した直後のプレ倒れ角は、０．７°以上であることが好ましい。プレ倒れ角が０．７°以上になるまで工程（Ｂ－１）を実行することにより、プレチルト方位をより確実に確定させることができる。 When a general CPA mode material (liquid crystal material, alignment film material) and a general photopolymerizable compound for PSA processing are used as the material of the liquid crystal display panel 100a, immediately after performing the step (B-1) The pre-tilt angle is preferably 0.7 ° or more. By executing step (B-1) until the pre-tilt angle becomes 0.7 ° or more, the pretilt azimuth can be determined more reliably.
　ただし、工程（Ｂ－１）を、プレ倒れ角が０．７°を大きく超えるようになるまで実行すると、小さなプレ倒れ角でのアンカリング効果が強くなってしまい、工程（Ｂ－２）に要する時間が長くなってしまうことがある。そのため、工程（Ｂ－１）を実行した直後のプレ倒れ角は、１．３°以下であることが好ましい。 However, if the step (B-1) is performed until the pre-tilt angle greatly exceeds 0.7 °, the anchoring effect at a small pre-tilt angle becomes strong, and the step (B-2) It may take a long time. For this reason, the pre-tilt angle immediately after the execution of the step (B-1) is preferably 1.3 ° or less.
　また、工程（Ｂ－２）を実行した後のプレ倒れ角は、典型的には、１．５°以上５．０°以下であり、工程（Ｂ－２）を実行した後のプレ倒れ角は、典型的には、工程（Ｂ－１）を実行した直後のプレ倒れ角のプレ倒れ角の１．２倍以上７倍以下である。 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).
　（実施形態２）
　図１２および図１３に、本実施形態における液晶表示装置１００Ａを示す。図１２は、液晶表示装置１００Ａの１つの画素に対応した領域を模式的に示す平面図である。図１３は、図１２中の１３Ａ－１３Ａ’線に沿った断面図であり、液晶層３０に電圧が印加されていない状態（しきい値電圧未満の電圧が印加されている状態）を示している。 (Embodiment 2)
12 and 13 show a liquid crystal display device 100A according to this embodiment. 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.
　本実施形態の液晶表示装置１００Ａは、微細なストライプ状パターン（「フィッシュボーン構造」と呼ばれる）を有する画素電極１１Ａを備えたＶＡモードの液晶表示装置である点において、実施形態１の液晶表示装置１００と異なっている。図１２および図１３では、実施形態１の液晶表示装置１００の構成要素と同じ機能を有する構成要素には同じ参照符号が付されており、以下では、それらの説明を省略する（以降の図面においても同様である）。 The liquid crystal display device 100A according to the present embodiment 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. In 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).
　液晶表示装置１００Ａの画素電極１１Ａは、図１２および図１３に示すように、十字形状の幹部１１ｃと、幹部１１ｃから略４５°方向に延びる複数の枝部１１ｄと、複数の枝部１１ｄ間に形成された複数のスリット１１ｅとを有する。 As shown in FIGS. 12 and 13, 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. A plurality of slits 11e formed.
　上述したようなフィッシュボーン構造を有する画素電極１１Ａと対向電極２１との間に電圧が印加されると、各画素内において、液晶分子３１が複数の方位に傾斜配向する。具体的には、各画素内において、液晶分子３１が４つの方位に傾斜配向し、液晶層３０に４つ（４種類）の液晶ドメインが形成される。 When a voltage is applied between the pixel electrode 11A having the fishbone structure as described above and the counter electrode 21, 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.
　ここで、図１４も参照しながら、画素電極１１Ａのより具体的な構造と、各液晶ドメインのディレクタの方位との関係を説明する。 Here, the relationship between the more specific structure of the pixel electrode 11A and the director orientation of each liquid crystal domain will be described with reference to FIG.
　図１４に示すように、画素電極１１Ａの幹部１１ｃは、水平方向に延びる直線部（水平直線部）１１ｃ１と、垂直方向に延びる直線部（垂直直線部）１１ｃ２とを有している。水平直線部１１ｃ１と垂直直線部１１ｃ２とは、画素の中央で互いに交差（直交）している。 As shown in FIG. 14, 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.
　複数の枝部１１ｄは、十字形状の幹部１１ｃによって分けられる４つの領域に対応する４つの群に分けられる。表示面を時計の文字盤に見立て、方位角の０°を３時方向とし、反時計回りを正とすると、複数の枝部１１ｄは、方位角４５°方向に延びる枝部１１ｄ１から構成される第１群、方位角１３５°方向に延びる枝部１１ｄ２から構成される第２群、方位角２２５°方向に延びる枝部１１ｄ３から構成される第３群および方位角３１５°方向に延びる枝部１１ｄ４から構成される第４群に分けられる。 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.
　第１群、第２群、第３群および第４群のそれぞれにおいて、複数の枝部１１ｄのそれぞれの幅Ｌおよび隣接する枝部１１ｄの間隔Ｓは、典型的には、１．５μｍ以上５．０μｍ以下である。液晶分子３１の配向の安定性および輝度の観点から、枝部１１ｄの幅Ｌおよび間隔Ｓは上記範囲内にあることが好ましい。なお、幹部１１ｃの水平直線部１１ｃ１から延びる枝部１１ｄの数および垂直直線部１１ｃ２から延びる枝部１１ｄの数は、図１２および図１４に例示しているものに限定されない。 In each of the first group, the second group, the third group, and the 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 μm or more and 5 0.0 μm 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.
　複数のスリット１１ｅのそれぞれは、隣接する枝部１１ｄと同じ方向に延びている。具体的には、第１群の枝部１１ｄ１間のスリット１１ｅは方位角４５°方向に延びており、第２群の枝部１１ｄ２間のスリット１１ｅは方位角１３５°方向に延びている。また、第３群の枝部１１ｄ３間のスリット１１ｅは方位角２２５°方向に延びており、第４群の枝部１１ｄ４間のスリット１１ｅは方位角３１５°方向に延びている。 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.
　電圧印加時には、各スリット（すなわち画素電極１１Ａの導電膜が存在しない部分）１１ｅに生成される斜め電界によって、液晶分子３１が傾斜する方位が規定される。この方位は、枝部１１ｄと平行（つまりスリット１１ｅと平行）で、且つ、幹部１１ｃに向かう方向（つまり枝部１１ｄの延伸方位と１８０°異なる方位）である。具体的には、第１群の枝部１１ｄ１によって規定される傾斜方位（第１方位：矢印Ａ）の方位角は約２２５°であり、第２群の枝部１１ｄ２によって規定される傾斜方位（第２方位：矢印Ｂ）の方位角は約３１５°であり、第３群の枝部１１ｄ３によって規定される傾斜方位（第３方位：矢印Ｃ）の方位角は約４５°であり、第４群の枝部１１ｄ４によって規定される傾斜方位（第４方位：矢印Ｄ）の方位角は約１３５°である。上記の４つの方位Ａ～Ｄは、電圧印加時に形成される４Ｄ構造における各液晶ドメインのディレクタの方位となる。方位Ａ～Ｄは、複数の枝部１１ｄのいずれかと略平行であり、一対の偏光板（不図示）の偏光軸と略４５°の角をなす。また、方位Ａ～Ｄの任意の２つの方位の差は９０°の整数倍に略等しく、幹部１１ｃを介して互いに隣接する液晶ドメインのディレクタの方位（例えば方位Ａと方位Ｂ）は略９０°異なる。 When the voltage is applied, 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 °). Specifically, the azimuth angle of the tilt azimuth (first azimuth: arrow A) defined by the first group of branches 11d1 is about 225 °, and 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.
　なお、画素電極１１Ａのフィッシュボーン構造は、図１２などに例示しているものに限定されず、公知のフィッシュボーン構造を適宜用いることができる。例えば、画素電極１１Ａは２つ以上の幹部１１ｃを有していてもよい。フィッシュボーン構造を有する画素電極は、例えば、特開２００３－１４９６４７号公報、特開２００６－７８９６８号公報、特開２００３－１７７４１８号公報などに開示されている。 Note that 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. For example, 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.
　上述したように、液晶表示装置１００Ａでは、画素電極１１Ａがフィッシュボーン構造を有していることによって、電圧印加時に各画素内において複数の液晶ドメインが形成される。本実施形態の液晶表示装置１００Ａにおいても、液晶表示パネル１００ａは、図１３に示すように、一対の垂直配向膜１６および２６のそれぞれの液晶層３０側の表面に設けられた配向維持層１８および２８を有する。配向維持層１８および２８が設けられていることにより、安定な傾斜配向（４Ｄ構造）を実現することができ、応答特性が向上する。 As described above, in the liquid crystal display device 100A, 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. Also in the liquid crystal display device 100A of the present embodiment, 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. By providing the alignment maintaining layers 18 and 28, stable tilted alignment (4D structure) can be realized, and response characteristics are improved.
　本願発明者の検討によれば、フィッシュボーン構造を有する画素電極を備え、ＰＳＡ技術が適用された液晶表示装置においても、ＰＳＡ処理の短時間化のためにＰＳＡ処理の際に高電圧を液晶層に印加すると、所望の方位からずれた方位に配向する液晶分子（図１４中に参照符号３１’を付した液晶分子）が存在し（つまり傾斜配向が乱れる）、表示品位が低下してしまうことがわかった。 According to the study of the present inventor, even in a 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. When applied to, there are liquid crystal molecules (liquid crystal molecules denoted by reference numeral 31 'in FIG. 14) that are aligned in a direction deviated from a desired direction (that is, the tilted alignment is disturbed), and the display quality is deteriorated. I understood.
　液晶表示装置１００Ａを製造する際のＰＳＡ工程を、実施形態１で説明したように２段階（画素電極１１Ａおよび対向電極２１の間に与えられる電位差が互いに異なる２つの工程（Ｂ－１）および（Ｂ－２））で実行することにより、傾斜配向の乱れに起因した表示品位の低下が抑制される。 As described in the first embodiment, 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). By executing the process in B-2)), the deterioration of display quality due to the disorder of the tilted orientation is suppressed.
　下記表２に、ＰＳＡ処理において、画素電極－対向電極間電圧が高電圧（例えば±１０Ｖ）である場合（比較例３）と、低電圧から高電圧へと（例えば±８Ｖから±１０Ｖ）２ステップに変化する場合（実施例２）について、ＰＳＡ処理における紫外線照射時間、装置処理能力の高低、電圧印加状態における配向状態の良し悪し、表示品位の良し悪しを示す。 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 In the case of changing to steps (Example 2), the ultraviolet irradiation time in the PSA process, the level of apparatus processing capability, the alignment state in the voltage application state, and the display quality are shown.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２に示されているように、比較例３では紫外線照射時間が６０～８０秒であり、実施例１でも紫外線照射時間は６０～８０秒である。そのため、比較例３および実施例２では装置処理能力が高くなる。 As shown in Table 2, 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.
　また、比較例３では、電圧印加状態における配向状態が良好ではない（悪い）のに対し、実施例２では、電圧印加状態における配向状態は良好である。図１５（ａ）に、比較例３における配向状態の例を示し、図１５（ｂ）に、実施例２における配向状態の例を示す。 In Comparative Example 3, the alignment state in the voltage application state is not good (bad), whereas in Example 2, the alignment state in the voltage application state is good. FIG. 15A shows an example of the alignment state in Comparative Example 3, and FIG. 15B shows an example of the alignment state in Example 2.
　比較例３では、図１５（ａ）に示すように、所望の方位Ａ～Ｄからずれた方位に倒れる液晶分子３１が存在する。これに対し、実施例２では、図１５（ｂ）に示すように、液晶分子３１はほぼ所望の方位Ａ～Ｄに倒れる。 In 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.
　また、表示光として直線偏光を用いる場合（つまり一対の偏光板が直線偏光板である場合）、比較例３では表示品位が悪い。これは、傾斜配向が乱れており、また、その程度が画素間で異なっているからである。 Further, when linearly polarized light is used as the display light (that is, when the pair of polarizing plates are linearly polarizing plates), the display quality is poor in Comparative Example 3. This is because the tilted orientation is disturbed and the degree differs between pixels.
　これに対し、実施例２では表示品位が良好である。これは、傾斜配向の乱れが発生せず、すべての画素で傾斜配向の状態がほぼ均一だからである。 On the other hand, in 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.
　また、表示光として円偏光を用いる場合（つまり一対の偏光板が円偏光板である場合）でも、比較例３では表示品位が悪い。これは、図１５（ａ）に示したような液晶分子３１の倒れ方が、画素あるいは色ごとに異なるため、表示がざらついたり、視角によって色味が変わったりすることがあるからである。 Even when circularly polarized light is used as the display light (that is, when the pair of polarizing plates is a circularly polarizing plate), the display quality in Comparative Example 3 is poor. This is because the manner in which the liquid crystal molecules 31 are tilted as shown in FIG. 15A differs for each pixel or color, so that the display may be rough or the color may change depending on the viewing angle.
　これに対し、実施例２では表示品位は良好である。これは、図１５（ｂ）に示したように、液晶分子３１がほぼ所望の方位Ａ～Ｄに倒れるからである。 In contrast, in 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.
　上述したように、ＰＳＡ工程（工程（Ｂ））を、プレチルト方位を実質的に確定させる工程（Ｂ－１）と、その後にプレチルト角をさらに増加させる工程（Ｂ－２）とに分けることにより、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置１００Ａを、傾斜配向の乱れに起因した表示品位の低下を抑制しつつ、効率良く製造することができる。つまり、良好な傾斜配向の実現と、ＰＳＡ処理時間の短時間化（およびそれによる処理タクトの短縮、気泡不良の発生リスクの低減）とを両立することができる。そのため、液晶表示装置１００Ａの表示品位を向上させつつ、高い歩留りで量産を行うことができる。また、装置処理能力を向上させつつ、信頼性を向上させることができる。 As described above, 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.
　（実施形態３）
　図１６に、本実施形態における液晶表示装置１００Ｂを示す。図１６は、液晶表示装置１００Ｂを模式的に示す断面図であり、液晶層３０に電圧が印加されていない状態（しきい値電圧未満の電圧が印加されている状態）を示している。 (Embodiment 3)
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).
　本実施形態における液晶表示装置１００Ｂでは、一対の垂直配向膜１６Ｌおよび２６Ｌは、光配向処理を施された光配向膜である。一対の光配向膜１６Ｌおよび２６Ｌのうちの一方によって規定されるプレチルト方向と、他方によって規定されるプレチルト方向とは互いに略９０°異なっており、これら２つのプレチルト方向の中間の方向にチルト方向（基準配向方向）が規定されている。液晶層３０に電圧が印加されたときには、液晶分子３１は、光配向膜１６Ｌおよび２６Ｌの配向規制力に従ってツイスト配向をとる。このように、プレチルト方向（配向処理方向）が互いに直交するように設けられた一対の垂直配向膜（光配向膜）１６Ｌおよび２６Ｌを用いることにより、液晶分子３１がツイスト配向となるＶＡモードは、ＶＡＴＮ（Vertical Alignment Twisted Nematic）モードあるいはＲＴＮ（Reverse Twisted Nematic）モードと呼ばれることもある。 In the liquid crystal display device 100B according to the present embodiment, 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. When a voltage is applied to the liquid crystal layer 30, the liquid crystal molecules 31 take a twist alignment according to the alignment regulating force of the photo- alignment films 16L and 26L. Thus, by using a pair of vertical alignment films (photo-alignment films) 16L and 26L provided so that the pretilt direction (alignment processing direction) is orthogonal to each other, 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.
　本実施形態では、一対の光配向膜１６Ｌおよび２６Ｌによる配向分割により、電圧印加時には４つの液晶ドメインが形成される（つまり４Ｄ構造が形成される）。４Ｄ構造が形成されるＲＴＮモードは、４Ｄ－ＲＴＮモードと呼ばれることもある。 In the present embodiment, due to the alignment division by the pair of photo- alignment films 16L and 26L, four liquid crystal domains are formed when a voltage is applied (that is, a 4D structure is formed). The RTN mode in which the 4D structure is formed may be referred to as a 4D-RTN mode.
　液晶表示装置１００Ｂの画素電極１１Ｂは、切欠き部やスリットなどが形成されていない、いわゆるべた電極であってよい。 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.
　ここで、光配向膜１６Ｌおよび２６Ｌによる配向分割方法を説明する。 Here, an alignment division method using the photo- alignment films 16L and 26L will be described.
　ここでは、図１７に例示する４分割配向構造の画素領域Ｐについて説明を行う。なお、図１７には、説明の簡単さのために、略正方形の画素電極に対応する略正方形の画素領域Ｐを示しているが、本発明は画素領域の形状に制限されるものではない。画素領域Ｐは略長方形であってもよい。 Here, the pixel region P having a four-part alignment structure illustrated in FIG. 17 will be described. For the sake of simplicity, FIG. 17 shows a substantially square pixel region P corresponding to a substantially square pixel electrode. However, the present invention is not limited to the shape of the pixel region. The pixel region P may be substantially rectangular.
　画素領域Ｐは、４つの液晶ドメインＬＤ１、ＬＤ２、ＬＤ３およびＬＤ４を有する。液晶ドメインＬＤ１、ＬＤ２、ＬＤ３およびＬＤ４のそれぞれのチルト方向（基準配向方向）をｔ１、ｔ２、ｔ３およびｔ４とすると、これらは、任意の２つの方向の差が９０°の整数倍に略等しい４つの方向である。図１７では、液晶ドメインＬＤ１、ＬＤ２、ＬＤ３およびＬＤ４の面積は互いに等しく、図１７に示す例は、視野角特性上最も好ましい４分割構造の例である。また、４つの液晶ドメインＬＤ１、ＬＤ２、ＬＤ３およびＬＤ４は、２行２列のマトリクス状に配置されている。 The pixel region P has four liquid crystal domains LD1, LD2, LD3, and LD4. When 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 There are two directions. In FIG. 17, 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.
　なお、ここで、液晶層３０を介して互いに対向する一対の偏光板（不図示）は、透過軸（偏光軸）が互いに略直交するように配置されており、より具体的には、一方の透過軸が表示面の水平方向に略平行で、他方の透過軸が表示面の垂直方向に略平行となるように配置されている。以下、特に示さない限り、偏光板の透過軸の配置はこれと同じである。 Here, the pair of polarizing plates (not shown) 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. Hereinafter, unless otherwise indicated, the arrangement of the transmission axes of the polarizing plates is the same.
　表示面における水平方向の方位角（３時方向）を０°とすると、液晶ドメインＬＤ１のチルト方向ｔ１は略２２５°方向であり、液晶ドメインＬＤ２のチルト方向ｔ２は略３１５°方向である。また、液晶ドメインＬＤ３のチルト方向ｔ３は略４５°方向であり、液晶ドメインＬＤ４のチルト方向ｔ４は略１３５°方向である。つまり、液晶ドメインＬＤ１、ＬＤ２、ＬＤ３およびＬＤ４は、それぞれのチルト方向が、隣接する液晶ドメイン間で略９０°異なるように配置されている。 When the horizontal azimuth angle (3 o'clock direction) on the display surface is 0 °, the tilt direction t1 of the liquid crystal domain LD1 is approximately 225 °, and 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 °, and 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.
　図１８（ａ）、（ｂ）および（ｃ）は、図１７に示した画素領域Ｐ１の分割方法を説明するための図である。図１８（ａ）は、アクティブマトリクス基板（第１基板）１０に設けられている光配向膜１６Ｌによって規定されるプレチルト方向ＰＡ１およびＰＡ２を示し、図１８（ｂ）は、対向基板（第２基板）２０に設けられている光配向膜２６Ｌによって規定されるプレチルト方向ＰＢ１およびＰＢ２を示している。また、図１８（ｃ）は、液晶層２０に電圧を印加したときのチルト方向を示している。これらの図では、観察者側から見たときの液晶分子３１の配向方向を模式的に示しており、円柱状に示した液晶分子３１の端部（楕円形部分）が描かれている方が観察者に近いように、液晶分子３１がチルトしていることを示している。 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. In these drawings, 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.
　アクティブマトリクス基板１０側の領域（１つの画素領域Ｐに対応する領域）は、図１８（ａ）に示すように、上下に２分割されており、それぞれの領域（上側領域と下側領域）の垂直配向膜１６Ｌに反平行なプレチルト方向ＰＡ１およびＰＡ２が付与されるように配向処理されている。ここでは、矢印で示した方向から偏光紫外線を斜め照射することによって光配向処理が行われている。 As shown in FIG. 18A, 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. Here, the photo-alignment process is performed by obliquely irradiating polarized ultraviolet rays from the direction indicated by the arrow.
　対向基板２０側の領域（１つの画素領域Ｐに対応する領域）は、図１８（ｂ）に示すように、左右に２分割されており、それぞれの領域（左側領域と右側領域）の垂直配向膜２６Ｌに反平行なプレチルト方向ＰＢ１およびＰＢ２が付与されるように配向処理されている。ここでは、矢印で示した方向から偏光紫外線を斜め照射することによって光配向処理が行われている。 As shown in FIG. 18B, 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. Here, the photo-alignment process is performed by obliquely irradiating polarized ultraviolet rays from the direction indicated by the arrow.
　図１８（ａ）および（ｂ）に示したように配向処理がなされたアクティブマトリクス基板１０および対向基板２０を貼り合わせることによって、図１８（ｃ）に示すように配向分割された画素領域Ｐを形成することができる。図１８（ｃ）からわかるように、液晶ドメインＬＤ１～ＬＤ４のそれぞれについて、アクティブマトリクス基板１０側の光配向膜１６Ｌによって規定されるプレチルト方向と、対向基板２０側の光配向膜２６Ｌによって規定されるプレチルト方向とは互いに略９０°異なっており、これら２つのプレチルト方向の中間の方向にチルト方向（基準配向方向）が規定されている。 By bonding the active matrix substrate 10 and the counter substrate 20 that have been subjected to the alignment process as shown in FIGS. 18A and 18B, the pixel region P that has been subjected to the alignment division as shown in FIG. Can be formed. As can be seen from FIG. 18C, for each of the liquid crystal domains LD1 to LD4, 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.
　本実施形態の液晶表示装置１００Ｂにおいても、図１６に示すように、液晶表示パネル１００Ｂは、配向維持層１８および２８を有する。以下、図１９（ａ）および（ｂ）を参照しながら、本実施形態における液晶表示装置１００Ｂの製造方法を説明する。 Also in the liquid crystal display device 100B of the present embodiment, the liquid crystal display panel 100B has alignment maintaining layers 18 and 28 as shown in FIG. Hereinafter, 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).
　まず、図１９（ａ）に示すように、液晶層３０中に光重合性化合物を含む液晶表示パネル１００ａを用意する（工程（Ａ））。次に、図１９（ｂ）に示すように、液晶表示パネル１００ａの画素電極１１Ｂおよび対向電極２１の間に電位差が与えられた状態で、液晶層３０に光（紫外線ＵＶ）を照射して液晶層３０中の光重合性化合物を重合することによって、配向維持層１８および２８を形成する（工程（Ｂ））。 First, as shown in FIG. 19A, a liquid crystal display panel 100a containing a photopolymerizable compound is prepared in the liquid crystal layer 30 (step (A)). Next, as shown in FIG. 19B, 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)).
　ここで、工程（Ａ）は、一対の光配向膜１６Ｌおよび２６Ｌのうちの一方の光配向膜１６Ｌに光を照射することによって、その光配向膜１６Ｌに互いに異なる（典型的には反平行な）プレチルト方向を規定する複数の領域を形成する工程（Ａ－１）と、他方の光配向膜２６Ｌに光を照射することによって、その光配向膜２６Ｌに互いに異なる（典型的には反平行な）プレチルト方向を規定する複数の領域を形成する工程（Ａ－２）とを含む。また、工程（Ａ）は、工程（Ａ－１）および（Ａ－２）の後に、アクティブマトリクス基板１０と対向基板２０とをシール剤を介して互いに貼り合わせ、その後、加熱によってシール剤を硬化する工程（Ａ－３）をさらに含む。 Here, 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 step (A-1) of forming a plurality of regions defining the pretilt direction and irradiating the other photo-alignment film 26L with light so that the photo-alignment film 26L is different from each other (typically antiparallel). And (A-2) forming a plurality of regions defining the pretilt direction. In the step (A), after the steps (A-1) and (A-2), 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.
　本実施形態の製造方法では、工程（Ａ－１）および（Ａ－２）は、一対の光配向膜１６Ｌおよび２６Ｌによって規定されるプレ倒れ角が所定の大きさ以上になるように実行される。そのことにより、配向維持層１８および２８によって規定されるプレチルト方位が実質的に確定される。 In the manufacturing method of the present embodiment, 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. . As a result, the pretilt orientation defined by the alignment sustaining layers 18 and 28 is substantially determined.
　一般に、光配向膜によってプレチルト方向を規定する場合、信頼性（プレ倒れ角の保持）が問題となる。具体的には、常時点灯させるような表示パターンでプレ倒れ角にばらつきが生じる「焼き付き」が問題となる。また、光配向処理（工程（Ａ－１）および（Ａ－２））後に行われるシール剤硬化工程（工程（Ａ－３））における熱処理（例えば１２０℃程度）によって、光配向処理の効果が薄れ、所望のプレ倒れ角を得られなかったり、配向不良が発生したりすることもある。 Generally, when the pretilt direction is defined by the photo-alignment film, reliability (pre-tilt angle retention) becomes a problem. Specifically, “burn-in” in which the pre-tilt angle varies in a display pattern that always lights up is a problem. In addition, 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.
　上述したような問題は、本実施形態のように、工程（Ａ）の後にＰＳＡ処理を行う（工程（Ｂ）を実行する）ことにより、解決し得る。特に、工程（Ａ－１）および（Ａ－２）を、一対の光配向膜１６Ｌおよび２６Ｌによって規定されるプレ倒れ角が所定の大きさ以上になるように実行し、それによって配向維持層１８および２８によって規定されるプレチルト方位を実質的に確定させることにより、上述したような問題の発生をより確実に防止することができる。 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. In particular, 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.
　工程（Ａ－１）および（Ａ－２）は、具体的には、一対の光配向膜１６Ｌおよび２６Ｌによって規定されるプレ倒れ角が２°以上になるように実行されることが好ましい。これにより、配向維持層１８および２８によって規定されるプレチルト方位をより確実に確定させることができる。また、工程（Ａ－３）における熱処理により、プレ倒れ角は小さくなるが、工程（Ａ－３）を実行した直後の一対の光配向膜１６Ｌおよび２６Ｌによって規定されるプレ倒れ角が０．７°以上であれば、配向維持層１８および２８によって規定されるプレチルト方位をより確実に確定させることができる。 Specifically, 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. Thereby, the pretilt azimuth | direction prescribed | regulated by the orientation maintenance layers 18 and 28 can be determined more reliably. Further, 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.
　例えば、工程（Ａ－１）および（Ａ－２）をプレ倒れ角が２°～３°になるように実行した場合、工程（Ａ－３）を実行した直後のプレ倒れ角は１°程度に下がるが、その後工程（Ｂ）（ＰＳＡ処理）を行うことにより、配向維持層１８および２８によって規定されるプレ倒れ角は、２．５°～４°程度となる。そのため、十分な配向規制を行うことができる。 For example, when the steps (A-1) and (A-2) are executed so that the pre-tilt angle is 2 ° to 3 °, the pre-tilt angle immediately after executing the step (A-3) is about 1 °. However, by performing the subsequent step (B) (PSA treatment), 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.
　本発明の実施形態によれば、ＰＳＡ技術が適用されたＶＡモードの液晶表示装置を、傾斜配向の乱れに起因した表示品位の低下を抑制しつつ、効率良く製造し得る製造方法が提供される。 According to the embodiments of the present invention, there is provided 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. .
　１０　　アクティブマトリクス基板（第１基板）
　１０ａ　　透明基板
　１１、１１Ａ、１１Ｂ　　画素電極
　１１ａ　　サブ画素電極
　１１ｂ　　切欠き部
　１１ｃ　　幹部
　１１ｄ　　枝部
　１１ｅ　　スリット
　１２　　走査配線
　１３　　信号配線
　１４　　補助容量配線
　１５　　層間絶縁層
　１６　　垂直配向膜
　１６Ｌ　　光配向膜（垂直配向膜）
　１８　　配向維持層
　２０　　対向基板（第２基板）
　２０ａ　　透明基板
　２１　　対向電極
　２１ａ　　開口部
　２２　　カラーフィルタ層
　２３　　凸部
　２６　　垂直配向膜
　２６Ｌ　　光配向膜（垂直配向膜）
　２８　　配向維持層
　３０　　液晶層
　３１　　液晶分子
　１００ａ　　液晶表示パネル
　１００、１００Ａ、１００Ｂ　　液晶表示装置 10 Active matrix substrate (first 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

Claims (11)

  1. 　第１基板と、第２基板と、前記第１基板および前記第２基板の間に設けられた垂直配向型の液晶層とを有する液晶表示パネルを備え、
    　マトリクス状に配列された複数の画素を有し、
    　前記第１基板は、前記複数の画素のそれぞれに設けられた画素電極を有し、
    　前記第２基板は、前記画素電極に対向する対向電極を有し、
    　前記液晶層に所定の電圧が印加されたときに、前記複数の画素のそれぞれ内において、前記液晶層の液晶分子が複数の方位に傾斜配向し、
    　前記液晶表示パネルは、前記画素電極および前記液晶層の間と前記対向電極および前記液晶層の間とに設けられた一対の垂直配向膜と、前記一対の垂直配向膜のそれぞれの前記液晶層側の表面に光重合物から形成された配向維持層であって、前記液晶層に電圧が印加されていないときに前記液晶分子のプレチルト方位およびプレ倒れ角を規定する配向維持層と、をさらに有する液晶表示装置の製造方法であって、
    　前記液晶層中に光重合性化合物を含む前記液晶表示パネルを用意する工程（Ａ）と、
    　前記液晶表示パネルの前記画素電極および前記対向電極の間に電位差が与えられた状態で、前記液晶層に光を照射して前記液晶層中の光重合性化合物を重合することによって、前記配向維持層を形成する工程（Ｂ）と、を包含し、
    　前記工程（Ｂ）は、
    　前記画素電極および前記対向電極の間に第１の電位差が与えられた状態で前記液晶層に光を照射することによって、前記配向維持層によって規定されるプレ倒れ角を増加させつつ、前記配向維持層によって規定されるプレチルト方位を実質的に確定させる工程（Ｂ－１）と、
    　前記工程（Ｂ－１）の後に、前記画素電極および前記対向電極の間に前記第１の電位差よりも大きな第２の電位差が与えられた状態で前記液晶層に光を照射することによって、前記プレ倒れ角をさらに増加させる工程（Ｂ－２）と、
    を含む液晶表示装置の製造方法。     A liquid crystal display panel having a first substrate, a second substrate, and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate;
    Having a plurality of pixels arranged in a matrix,
    The first substrate has a pixel electrode provided on each of the plurality of pixels,
    The second substrate has a counter electrode facing the pixel electrode,
    When a predetermined voltage is applied to the liquid crystal layer, the liquid crystal molecules of the liquid crystal layer are tilted and aligned in a plurality of directions in each of the plurality of pixels.
    The liquid crystal display 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 the liquid crystal layer side of each of the pair of vertical alignment films An alignment maintaining layer formed of a photopolymer on the surface of the liquid crystal layer, the alignment maintaining layer defining a pretilt azimuth and a pre-tilt angle of the liquid crystal molecules when no voltage is applied to the liquid crystal layer. A method of manufacturing a liquid crystal display device,
    Preparing the liquid crystal display panel containing a photopolymerizable compound in the liquid crystal layer (A);
    The alignment is maintained by polymerizing the photopolymerizable compound in the liquid crystal layer by irradiating the liquid crystal layer with light while a potential difference is applied between the pixel electrode and the counter electrode of the liquid crystal display panel. Forming a layer (B),
    The step (B)
    Irradiation of light to the liquid crystal layer with a first potential difference applied between the pixel electrode and the counter electrode increases the pre-tilt angle defined by the alignment maintaining layer and maintains the alignment. The step of substantially determining the pretilt orientation defined by the layer (B-1);
    After the step (B-1), by irradiating the liquid crystal layer with light in a state where a second potential difference larger than the first potential difference is applied between the pixel electrode and the counter electrode, A step of further increasing the pre-tilt angle (B-2);
    A manufacturing method of a liquid crystal display device including
  2. 　前記第１の電位差は、前記複数の画素のそれぞれ内における前記液晶分子の傾斜配向の対称性が、前記画素電極および前記対向電極の間に与えられる電位差を前記第１の電位差としたときに実質的にもっとも高くなるように設定される請求項１に記載の液晶表示装置の製造方法。 The first potential difference is substantially equal when the symmetry of the tilt alignment of the liquid crystal molecules in each of the plurality of pixels is the potential difference applied between the pixel electrode and the counter electrode as the first potential difference. The method for manufacturing a liquid crystal display device according to claim 1, wherein the liquid crystal display device is set to be highest.
  3. 　前記第２の電位差は、前記第１の電位差の１．２倍以上１５倍以下である請求項１または２に記載の液晶表示装置の製造方法。 3. The method of manufacturing a liquid crystal display device according to claim 1, wherein the second potential difference is 1.2 times to 15 times the first potential difference.
  4. 　前記工程（Ｂ－２）を実行した後の前記プレ倒れ角は、前記工程（Ｂ－１）を実行した直後の前記プレ倒れ角の１．２倍以上７倍以下である請求項１から３のいずれかに記載の液晶表示装置の製造方法。 The pre-tilt angle after executing the step (B-2) is 1.2 to 7 times the pre-tilt angle immediately after executing the step (B-1). A method for producing a liquid crystal display device according to any one of the above.
  5. 　前記工程（Ｂ－１）を実行した直後の前記プレ倒れ角は０．７°以上である請求項１から４のいずれかに記載の液晶表示装置の製造方法。 The method for manufacturing a liquid crystal display device according to any one of claims 1 to 4, wherein the pre-tilt angle immediately after executing the step (B-1) is 0.7 ° or more.
  6. 　前記液晶層に所定の電圧が印加されたときに、前記複数の画素のそれぞれ内において、前記液晶分子は軸対称配向をとる請求項１から５のいずれかに記載の液晶表示装置の製造方法。 6. The method of manufacturing a liquid crystal display device according to claim 1, wherein the liquid crystal molecules are axially symmetric in each of the plurality of pixels when a predetermined voltage is applied to the liquid crystal layer.
  7. 　前記画素電極は、少なくとも１つの十字形状の幹部と、前記少なくとも１つの十字形状の幹部から略４５°方向に延びる複数の枝部と、前記複数の枝部間に形成された複数のスリットと、を有する請求項１から５のいずれかに記載の液晶表示装置の製造方法。 The pixel electrode includes 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 a plurality of slits formed between the plurality of branches. A method for manufacturing a liquid crystal display device according to claim 1, comprising:
  8. 　第１基板と、第２基板と、前記第１基板および前記第２基板の間に設けられた垂直配向型の液晶層とを有する液晶表示パネルを備え、
    　マトリクス状に配列された複数の画素を有し、
    　前記第１基板は、前記複数の画素のそれぞれに設けられた画素電極を有し、
    　前記第２基板は、前記画素電極に対向する対向電極を有し、
    　前記液晶層に所定の電圧が印加されたときに、前記複数の画素のそれぞれ内において、前記液晶層の液晶分子が複数の方位に傾斜配向し、
    　前記液晶表示パネルは、前記画素電極および前記液晶層の間と前記対向電極および前記液晶層の間とに設けられた一対の垂直配向膜と、前記一対の垂直配向膜のそれぞれの前記液晶層側の表面に光重合物から形成された配向維持層であって、前記液晶層に電圧が印加されていないときに前記液晶分子のプレチルト方位およびプレ倒れ角を規定する配向維持層と、をさらに有し、
    　前記一対の垂直配向膜は、一対の光配向膜である液晶表示装置の製造方法であって、
    　前記液晶層中に光重合性化合物を含む前記液晶表示パネルを用意する工程（Ａ）と、
    　前記液晶表示パネルの前記画素電極および前記対向電極の間に電位差が与えられた状態で、前記液晶層に光を照射して前記液晶層中の光重合性化合物を重合することによって、前記配向維持層を形成する工程（Ｂ）と、を包含し、
    　前記工程（Ａ）は、
    　前記一対の光配向膜のうちの一方の光配向膜に光を照射することによって、前記一方の光配向膜に、互いに異なるプレチルト方向を規定する複数の領域を形成する工程（Ａ－１）と、
    　前記一対の光配向膜のうちの他方の光配向膜に光を照射することによって、前記他方の光配向膜に、互いに異なるプレチルト方向を規定する複数の領域を形成する工程（Ａ－２）と、を含み、
    　前記工程（Ａ－１）および（Ａ－２）は、前記一対の光配向膜によって規定されるプレ倒れ角が所定の大きさ以上になるように実行され、そのことにより、前記配向維持層によって規定されるプレチルト方位が実質的に確定される、液晶表示装置の製造方法。     A liquid crystal display panel having a first substrate, a second substrate, and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate;
    Having a plurality of pixels arranged in a matrix,
    The first substrate has a pixel electrode provided on each of the plurality of pixels,
    The second substrate has a counter electrode facing the pixel electrode,
    When a predetermined voltage is applied to the liquid crystal layer, the liquid crystal molecules of the liquid crystal layer are tilted and aligned in a plurality of directions in each of the plurality of pixels.
    The liquid crystal display 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 the liquid crystal layer side of each of the pair of vertical alignment films An alignment maintaining layer formed of a photopolymer on the surface of the liquid crystal layer, the alignment maintaining layer defining a pretilt orientation 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 is a method for manufacturing a liquid crystal display device which is a pair of photo-alignment films,
    Preparing the liquid crystal display panel containing a photopolymerizable compound in the liquid crystal layer (A);
    The alignment is maintained by polymerizing the photopolymerizable compound in the liquid crystal layer by irradiating the liquid crystal layer with light while a potential difference is applied between the pixel electrode and the counter electrode of the liquid crystal display panel. Forming a layer (B),
    The step (A)
    (A-1) forming a plurality of regions defining different pretilt directions in the one photo-alignment film by irradiating one of the pair of photo-alignment films with light; ,
    (A-2) 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; Including,
    Steps (A-1) and (A-2) are performed such that the pre-tilt angle defined by the pair of photo-alignment films is greater than or equal to a predetermined magnitude, whereby the alignment maintaining layer A method for manufacturing a liquid crystal display device, wherein a prescribed pretilt direction is substantially determined.
  9. 　前記工程（Ａ－１）および（Ａ－２）は、前記一対の光配向膜によって規定されるプレ倒れ角が２°以上になるように実行される請求項８に記載の液晶表示装置の製造方法。 9. The manufacture of a liquid crystal display device according to claim 8, wherein 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. Method.
  10. 　前記工程（Ａ）は、前記工程（Ａ－１）および（Ａ－２）の後に、
    　前記第１基板と前記第２基板とをシール剤を介して互いに貼り合わせ、その後、加熱によって前記シール剤を硬化する工程（Ａ－３）をさらに含む請求項８または９に記載の液晶表示装置の製造方法。     In the step (A), after the steps (A-1) and (A-2),
    10. The liquid crystal display device according to claim 8, further comprising a step (A-3) of bonding the first substrate and the second substrate to each other via a sealant, and then curing the sealant by heating. Manufacturing method.
  11. 　前記工程（Ａ－３）を実行した直後の前記一対の光配向膜によって規定されるプレ倒れ角は０．７°以上である請求項１０に記載の液晶表示装置の製造方法。 The method for manufacturing a liquid crystal display device according to claim 10, wherein a pre-tilt angle defined by the pair of photo-alignment films immediately after the execution of the step (A-3) is 0.7 ° or more.
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