WO2013047597A1 - Liquid crystal display device - Google Patents

Liquid crystal display device Download PDF

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Publication number
WO2013047597A1
WO2013047597A1 PCT/JP2012/074735 JP2012074735W WO2013047597A1 WO 2013047597 A1 WO2013047597 A1 WO 2013047597A1 JP 2012074735 W JP2012074735 W JP 2012074735W WO 2013047597 A1 WO2013047597 A1 WO 2013047597A1
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WIPO (PCT)
Prior art keywords
liquid crystal
substrate
display device
electrode
crystal display
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PCT/JP2012/074735
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French (fr)
Japanese (ja)
Inventor
村田　充弘
洋典 岩田
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シャープ株式会社
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Publication of WO2013047597A1 publication Critical patent/WO2013047597A1/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
    • G02F1/137—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 characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/139—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 characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
    • G02F1/1393—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 characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells
    • 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
    • G02F1/133738—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers for homogeneous alignment
    • 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
    • G02F1/133757—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 alignment orientations
    • 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
    • G02F1/137—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 characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/13787—Hybrid-alignment cells

Definitions

  • the present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device that can achieve both high transmittance and a wide viewing angle with a simple pixel structure.
  • a liquid crystal display device is configured by sandwiching a liquid crystal display element between a pair of glass substrates, etc., and is indispensable for daily life and business, such as mobile applications, various monitors, and televisions, taking advantage of its thin, lightweight, and low power consumption. It is impossible. In recent years, it has been widely used for electronic books, photo frames, IA (industrial equipment), PCs (personal computers), tablet PCs, smartphones, and the like. In these applications, liquid crystal display panels of various modes related to electrode arrangement and substrate design for changing the optical characteristics of the liquid crystal layer have been studied.
  • a liquid crystal display device in which a liquid crystal with positive dielectric anisotropy is sandwiched between a TFT substrate on which an electrode for driving liquid crystal is formed and a counter substrate on which a color filter is formed, and the TFT substrate includes: A pixel electrode and a common electrode are formed, one pixel is partitioned into a plurality of regions by the pixel electrode and the common electrode, and an initial alignment of the liquid crystal is perpendicular to the TFT substrate or the counter substrate, The direction of the liquid crystal molecules can be changed by applying a voltage between the pixel electrode and the common electrode, and the direction of the liquid crystal molecules when the voltage is applied is determined by the protrusions formed on the counter substrate.
  • a liquid crystal display device is disclosed in which the orientation of the liquid crystal molecules in the plurality of regions when the voltage is applied is controlled for each of the regions, and is different for each of the plurality of regions. (E.g., see Patent Document 1.).
  • a liquid crystal display device having a liquid crystal having a dielectric anisotropy singular point control is performed so that a singular point of an orientation vector field of the liquid crystal is formed at a predetermined position when a voltage is applied between the electrodes.
  • a liquid crystal display device having a portion and controlling the alignment of the liquid crystal using at least the formed singular point see, for example, Patent Document 2.
  • Patent Document 1 described above discloses widening of the viewing angle by four domains in a HAN (Hybrid Aligned Nematic) structure (a structure of a liquid crystal display device in which a liquid crystal is a hybrid alignment nematic liquid crystal). Further, Patent Document 2 described above discloses multi-domain formation in a radial alignment pattern by VA (vertical alignment; vertical alignment).
  • VA vertical alignment; vertical alignment
  • Patent Document 1 since the pixel electrode has a bowl shape, particularly in the design with a small pixel, the aperture ratio is lost due to the electrode portion, and there is room for improvement to improve the transmittance. There was also no disclosure of the type of polarizing plate. Patent Document 2 discloses a multi-domain technique in a pixel in VA. However, as in Patent Document 1, in particular, in a small pixel, the aperture ratio is reduced due to the arrangement of electrodes, and the transmittance is improved. There was room for ingenuity. In other words, as the display becomes more sophisticated, there is still a demand for a technology that maintains viewing angle performance and improves the transmittance, particularly with small pixels.
  • a liquid crystal display device having a particularly small pixel pitch e.g., 18 ⁇ m, equivalent to 470 ppi
  • the effective alignment region in the pixel is extremely lowered and the transmittance is drastically reduced.
  • two domains can be mentioned, but this deteriorates the viewing angle characteristics.
  • TBA Transverse Bend ⁇ ⁇ ⁇ Alignment
  • the present invention has been made in view of the above situation, and an object of the present invention is to provide a liquid crystal display device capable of achieving both high transmittance and a wide viewing angle.
  • the present inventors have made various studies on a liquid crystal panel capable of maintaining viewing angle performance and improving transmittance.
  • the conventional liquid crystal display device has been multi-domained by an electrode structure. I found that the rate was impaired. Then, paying attention to devising the orientation control layer, various methods for making the transmittance sufficient were examined. Then, the pixels when the main surface of the substrate is viewed in plan are divided vertically into the vertical direction, and the alignment control layer of the lower substrate (first substrate) when viewed in cross section is horizontal alignment (also referred to as parallel alignment). It was found that the orientation control layer of the upper substrate (second substrate) has a vertically oriented HAN structure.
  • the parallel alignment control region of the first substrate is set to at least two or more types, that is, the initial direction by optical alignment is 90 °, 270 ° (for example, FIG. 6), the domain is divided into two parts vertically, and the phase difference of the panel (also referred to as retardation or Re.
  • the unit is nm) and the phase difference of one wavelength in total in the same direction. It is possible to achieve both high transmittance and wide viewing angle by using a plate or a retardation plate having a retardation of the same size as the retardation of the panel in the orthogonal direction, in particular, by using a circularly polarizing plate.
  • the present inventors have found out what can be done and have conceived that the above-mentioned problems can be solved brilliantly, and have reached the present invention.
  • the present invention is a liquid crystal cell comprising a first substrate, a second substrate, and a liquid crystal layer sandwiched between both substrates, and a polarizing plate, wherein the liquid crystal layer comprises: Liquid crystal molecules having positive dielectric anisotropy, wherein the first substrate has an orientation control layer, a first electrode, and a second electrode, the second substrate has an orientation control layer, and The alignment control layer of the first substrate aligns liquid crystal molecules below the threshold voltage horizontally with respect to the substrate main surface. When the substrate main surface is viewed in plan, the liquid crystal molecules are unidirectionally arranged in the pixel.
  • An alignment control region for aligning liquid crystal molecules and an alignment control region for aligning liquid crystal molecules in a direction different from the direction, and the alignment control layer of the second substrate has liquid crystal molecules having a voltage lower than a threshold voltage on the main surface of the substrate.
  • the liquid crystal display device is oriented vertically.
  • the liquid crystal display device of the present invention is a high-definition pixel and can achieve a wide viewing angle and high transmittance by using photo-alignment (parallel).
  • L / S line / space
  • the aperture ratio is improved with a simple pixel structure.
  • the transmittance is remarkably high.
  • four domains can be formed and the viewing angle is good.
  • the first electrode and the second electrode usually include a plurality of linear portions.
  • the orientation of the liquid crystal is controlled by the electric field generated between the first electrode and the second electrode, and transmissive display is performed.
  • the first electrode and the second electrode are linear electrodes, and it is preferable that L / S (line / space) is substantially a pair between pixels.
  • the first electrode and the second electrode include a linear portion, and the linear portion of the first electrode and the linear portion of the second electrode are along each other.
  • the first electrode and the second electrode may constitute a pair of comb electrodes.
  • the linear portion of the first electrode and the linear portion of the second electrode are parallel to each other. The present invention can achieve a wide viewing angle with a simple pixel structure capable of improving the transmittance.
  • the first electrode and the second electrode can have different potentials at a threshold voltage or higher.
  • the threshold voltage means, for example, a voltage value that gives a transmittance of 5% when the transmittance in the bright state is set to 100%.
  • the potential different from the threshold voltage can be any voltage as long as it can realize a driving operation with a potential different from the threshold voltage. This makes it possible to suitably control the electric field applied to the liquid crystal layer. Become.
  • a preferable upper limit value of the different potential is, for example, 20V.
  • As a configuration that can be set to different potentials for example, one of the first electrode and the second electrode is driven by a certain TFT, and the other electrode is driven by another TFT.
  • the first electrode and the second electrode can be set to different potentials.
  • the width of the linear portion is preferably 2 ⁇ m or more, for example.
  • the width (also referred to as a space in this specification) between the linear portion of the first electrode and the linear portion of the second electrode is preferably 2 to 7 ⁇ m, for example.
  • the alignment control layer of the first substrate is preferably a photo-alignment film.
  • the alignment control layer of the second substrate is also preferably a photo-alignment film.
  • the liquid crystal display device includes a retardation plate on a side opposite to the liquid crystal layer of the first substrate and / or the second substrate, and the optical axis of the retardation plate is the first when the substrate main surface is viewed in plan view.
  • the orientation control layer of the substrate is along the direction in which the liquid crystal molecules are aligned at a value less than the threshold voltage, and the sum of the in-plane retardation of the retardation plate and the in-plane retardation at less than the threshold voltage of the liquid crystal cell is One wavelength, in other words, 530 to 570 nm is preferable. More preferably, the optical axis of the retardation plate is substantially parallel to the direction in which the alignment control layer of the first substrate aligns liquid crystal molecules below the threshold voltage when the substrate main surface is viewed in plan.
  • the crossed Nicol black changes to the maximum white state when the ⁇ / 2 plate is set to be shifted by 45 ° from the crossing angle.
  • Y value visible light
  • 275 nm corresponds to ⁇ / 2. That is, ⁇ is 550 nm. From this, the range of one wavelength is about 20 nm before and after that (530 to 570 nm), and if it is outside this range, it will not be black (contrast ratio [CR] is bad).
  • the liquid crystal display device includes a retardation plate on a side opposite to the liquid crystal layer of the first substrate and / or the second substrate, and the optical axis of the retardation plate is the first when the substrate main surface is viewed in plan view.
  • the alignment control layer of the substrate intersects the direction in which liquid crystal molecules are aligned below the threshold voltage, and the in-plane retardation of the retardation plate is substantially the same as the in-plane retardation of the liquid crystal cell below the threshold voltage. It is also preferred that it be.
  • the optical axis of the retardation plate is particularly preferably substantially perpendicular to the direction in which the alignment control layer of the first substrate aligns the liquid crystal molecules below the threshold voltage when the substrate main surface is viewed in plan.
  • a compensation retardation plate on the light incident side of the liquid crystal panel is preferable.
  • one retardation plate is disposed on the light incident side of the liquid crystal panel, a ⁇ / 4 plate is disposed so as to sandwich the liquid crystal panel and the retardation plate from above and below, and the ⁇ / 4 plate is sandwiched.
  • a polarizing plate is preferably disposed.
  • the distance between the first electrode and the second electrode increases as the distance from the boundary between the orientation control regions increases when the main surface of the substrate is viewed in plan. Thereby, viewing angle characteristics can be further improved.
  • the second substrate has a third electrode, and the third electrode is preferably planar and has a hole for orientation control. Thereby, viewing angle characteristics can be further improved.
  • the second substrate in the liquid crystal display device of the present invention may further include a third electrode. Thereby, an electric field can be effectively generated between the third electrode and the first electrode.
  • the second substrate may have an alignment regulation structure. Thereby, the stability of the alignment of the liquid crystal molecules can be improved.
  • the alignment regulating structure include an opening formed in the third electrode and a protrusion formed on the third electrode.
  • the second substrate has a third electrode, and it is particularly preferable that the third electrode is planar and has an alignment control hole.
  • the first electrode and the second electrode may be formed in different layers, but are preferably formed on the same insulating layer.
  • the first substrate preferably includes, for example, an alignment control layer from the liquid crystal layer side, first and second electrodes formed in the same layer, and an insulating layer.
  • the first electrode is a pixel electrode
  • the second electrode is a common electrode
  • the first substrate may further include a fourth electrode, and the liquid crystal layer is driven by an electric field generated by at least the first electrode, the second electrode, the third electrode, and the fourth electrode. May be.
  • the fourth electrode is preferably planar. Thereby, an electric field can be effectively generated between the fourth electrode and another electrode.
  • the liquid crystal panel of the present invention may be a horizontal alignment type liquid crystal panel, but is preferably a vertical alignment type liquid crystal panel from the viewpoint of improving contrast.
  • a general vertical alignment type liquid crystal panel has room for improvement in viewing angle characteristics.
  • the liquid crystal panel of the present invention is excellent in viewing angle characteristics. Therefore, when the liquid crystal panel of the present invention is a vertical alignment type liquid crystal panel, both a wide viewing angle and a high contrast can be achieved.
  • the liquid crystal layer includes liquid crystal molecules having positive dielectric anisotropy.
  • the liquid crystal layer is preferably composed of liquid crystal molecules having substantially positive dielectric anisotropy.
  • the polarizing plate in the present invention is preferably a circular polarizing plate. Moreover, it is also preferable that the polarizing plate in the present invention is a linear polarizing plate. According to the former, the transmittance can be improved. According to the latter, the viewing angle characteristics can be further improved. Note that a general liquid crystal panel including a circularly polarizing plate has room for improvement in viewing angle characteristics. On the other hand, the liquid crystal panel of the present invention is excellent in viewing angle characteristics. Therefore, when the liquid crystal panel of the present invention further comprises a circularly polarizing plate, high transmittance and a wide viewing angle can be made particularly excellent.
  • the kind and structure of the said circularly-polarizing plate are not specifically limited,
  • area can be used.
  • it is a laminate of a retardation plate and a linear polarizing plate (linear polarizer), but a structure (for example, cholesteric liquid crystal) having a helical structure at an optical pitch may be used.
  • the kind and structure of the said linear polarizing plate are not specifically limited,
  • area can be used.
  • the widths of the line and space of the first electrode and the second electrode, that is, the linear portion and the slit can be set as appropriate, but the width L of the linear portion is usually 1 to 8 ⁇ m (preferably 2 to 4 ⁇ m), and the slit width S is 1 to 8 ⁇ m (preferably 2 to 7 ⁇ m). It is preferable that the average value of L / S in one pixel is constant between pixels.
  • the cell gap d is about 2.8 to 4.5 ⁇ m (preferably 3.0 to 3.4 ⁇ m).
  • the pixel in the present invention is preferably a high-definition pixel, and for example, a pixel pitch of 10 to 150 ⁇ m in the vertical and horizontal directions is preferable. A more preferable upper limit value is 80 ⁇ m.
  • the liquid crystal display device of the present invention may be any of a transmissive type, a reflective type, and a transflective type.
  • the first substrate and the second substrate preferably includes a thin film transistor element, and the thin film transistor element preferably includes an oxide semiconductor.
  • the thin film transistor element included in the first substrate more preferably includes an oxide semiconductor.
  • the configuration of the liquid crystal display device of the present invention can be clarified by disassembling the liquid crystal display panel and analyzing the substrate opposite to the TFT array substrate.
  • the configuration of the liquid crystal drive device and the liquid crystal display device of the present invention is not particularly limited by other components as long as such components are formed as essential, and the liquid crystal drive device and the liquid crystal display are not limited.
  • Other configurations normally used in the apparatus can be applied as appropriate.
  • each form mentioned above may be combined suitably in the range which does not deviate from the summary of this invention.
  • liquid crystal display device that can achieve both high transmittance and a wide viewing angle.
  • FIG. 3 is a schematic cross-sectional view illustrating the liquid crystal display device with a voltage lower than the threshold voltage according to the first embodiment.
  • FIG. 5 is a schematic diagram showing tilt angle provision (alignment division) to liquid crystal molecules by photo-alignment in the vicinity of the first substrate at a voltage lower than the threshold voltage according to the first embodiment.
  • FIG. 3 is a schematic cross-sectional view showing the liquid crystal display device having a voltage equal to or higher than the threshold voltage according to the first embodiment.
  • FIG. 5 is a schematic diagram showing tilt angle provision (alignment division) to liquid crystal molecules by photo-alignment near the first substrate at a threshold voltage or higher according to Embodiment 1.
  • FIG. 6 is a simulation result showing a transmittance and a liquid crystal alignment state of a cross section of the liquid crystal display device at a threshold voltage or higher in the first embodiment.
  • 1 is a schematic plan view showing a liquid crystal display device according to Embodiment 1.
  • FIG. 3 is a schematic plan view illustrating a transmittance distribution and the like of the liquid crystal display device according to Embodiment 1.
  • FIG. 6 is a schematic plan view showing a liquid crystal display device according to Embodiment 2.
  • FIG. FIG. 6 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Embodiment 2.
  • 6 is a schematic plan view showing a liquid crystal display device according to Embodiment 3.
  • FIG. 6 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Embodiment 3.
  • 6 is a schematic plan view showing a liquid crystal display device according to Embodiment 4.
  • FIG. 6 is a schematic plan view illustrating a transmittance distribution and the like of a liquid crystal display device according to a fourth embodiment.
  • FIG. 10 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Embodiment 5.
  • FIG. 10 is a schematic plan view illustrating a transmittance distribution and the like of a liquid crystal display device according to Embodiment 6.
  • FIG. 10 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Embodiment 7.
  • FIG. 10 is a schematic plan view illustrating a transmittance distribution and the like of a liquid crystal display device according to Embodiment 8.
  • FIG. It is a figure which shows another example of arrangement
  • FIG. 6 is a schematic plan view showing a liquid crystal display device according to Comparative Example 1.
  • FIG. 6 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Comparative Example 1.
  • FIG. 10 is a schematic plan view showing a liquid crystal display device according to Comparative Example 2.
  • FIG. 6 is a schematic plan view showing a liquid crystal display device according to Reference Example 1.
  • FIG. It is a plane schematic diagram which shows the transmittance
  • FIG. 10 is a schematic plan view showing a liquid crystal display device according to Comparative Example 3.
  • FIG. It is a plane schematic diagram which shows the transmittance
  • 1 is a schematic plan view illustrating one embodiment of a thin film transistor.
  • 1 is a schematic plan view illustrating one embodiment of a thin film transistor.
  • each pixel is composed of a plurality of (usually three) picture elements.
  • the pixel may be a pixel (sub-pixel).
  • “orienting horizontally (parallel)” means aligning horizontally (parallel) to the main surface of the substrate.
  • the direction is represented by an angle (°) when the clock is rotated clockwise with the 3 o'clock direction of the clock set to 0 °.
  • members and portions that exhibit the same function are denoted by the same reference numerals except that the hundreds are changed.
  • the POL axis indicates a polarizer or analyzer of a linear polarizing plate.
  • the double-dotted arrow on the picture element region indicates the domain direction.
  • FIG. 1 is a schematic cross-sectional view illustrating a liquid crystal display device having a voltage lower than the threshold voltage according to the first embodiment.
  • FIG. 2 is a schematic diagram illustrating the provision of a tilt angle (alignment division) to liquid crystal molecules by photo-alignment in the vicinity of the first substrate at a voltage lower than the threshold voltage according to the first embodiment.
  • FIG. 3 is a schematic cross-sectional view showing the liquid crystal display device at a threshold voltage or higher according to the first embodiment.
  • FIG. 4 is a schematic diagram illustrating the provision of a tilt angle (alignment division) to liquid crystal molecules by photoalignment in the vicinity of the first substrate at a threshold voltage or higher according to the first embodiment.
  • the liquid crystal display device of Embodiment 1 includes an active matrix substrate (TFT array substrate) corresponding to a first substrate 10 having a drive electrode for a lateral electric field, a color filter on the glass substrate 21 facing the first substrate 10.
  • a second substrate 20 having a columnar spacer (not shown) disposed from the color filter layer in order to laminate a (CF) layer (not shown) and maintain a distance between the substrates;
  • the liquid crystal layer 30 is sandwiched between the second substrate 20 and the second substrate 20.
  • the first substrate 10 is provided on the back side of the liquid crystal display, and the second substrate 20 is provided on the viewer side.
  • the first substrate 10 and the second substrate 20 are bonded together by a sealing material provided so as to surround the display area.
  • the liquid crystal display device of Embodiment 1 has the following features (1) to (4).
  • the first substrate 10 having the drive electrodes according to the present embodiment has a structure that generates a parallel electric field.
  • a comb-like electrode (corresponding to the pixel electrode 13 corresponding to the first electrode and the second electrode) formed by photolithography or the like using IZO (or ITO) or the like.
  • Common electrode 15 is configured.
  • the second substrate 20 having a color filter facing the first substrate 10 is configured to planarize the color filter with an overcoat layer (OC), and the inside of the overcoat layer or the upper portion (over Columnar spacers are provided on the liquid crystal layer 30 side of the coating layer.
  • a photo-alignment film (parallel) is used for the first substrate 10, and a vertical alignment film is used for the second substrate 20.
  • the orientation is divided at the center of the electrode.
  • the first substrate 10 aligns neighboring liquid crystal molecules horizontally (parallel)
  • the second substrate 20 uses neighboring liquid crystal molecules.
  • a HAN structure in which is vertically oriented.
  • the liquid crystal layer uses liquid crystal molecules having positive dielectric anisotropy and is driven by a lateral electric field.
  • the driving electrodes are formed by sputtering indium tin oxide (ITO) on the glass substrate 11 on one side to a thickness of 1400 mm.
  • ITO indium tin oxide
  • IZO indium zinc oxide
  • a positive type liquid crystal material ( ⁇ 23) manufactured by Merck Co., Ltd. was sealed by a vacuum injection method, and a circularly polarizing plate was bonded thereto to produce a liquid crystal display element.
  • the alignment state at the time of voltage application is substantially divided into four domains by obtaining complementary alignment compensation symmetrically at the center of the electrode interval and at the same time performing complementary alignment compensation at the parallel alignment division at the center of the pixel.
  • the name of this mode is also called 4D-HBA (4 domain, hybrid bend alignment).
  • the circularly polarizing plate is an optical element that transmits one of right circularly polarized light and left circularly polarized light and absorbs or reflects the other.
  • FIG. 5 is a simulation result showing the transmittance and the liquid crystal alignment state of the cross section of the liquid crystal display device above the threshold voltage of the first embodiment. The simulation was performed using LCD-Master 3D manufactured by Shintech. D represents a director.
  • the liquid crystal display device of the present embodiment includes a liquid crystal panel, a backlight unit (not shown) provided behind the liquid crystal panel, and a control unit (see FIG. 5) for driving and controlling the liquid crystal panel and the backlight unit. (Not shown).
  • a thin film transistor TFT
  • a pixel electrode corresponding to the first electrode 13 and provided in each pixel
  • a common electrode corresponding to the second electrode 15 and provided in each pixel
  • An alignment film is formed.
  • a region divided by the gate bus line and the source bus line is approximately one picture element region.
  • a color filter layer (not shown) and a vertical alignment film are laminated in this order.
  • a counter electrode corresponding to the third electrode may be provided between the color filter layer and the vertical alignment film.
  • the counter electrode has a planar shape and is formed without a cut so as to cover at least the entire display area.
  • the vertical alignment film is formed without a break so as to cover at least the entire display region.
  • the vertical alignment film can align liquid crystal molecules in the vicinity in a direction substantially perpendicular to the film surface.
  • the material of the vertical alignment film may be an organic alignment film formed using an organic material including polyimide or the like, or an inorganic alignment film formed using an inorganic material including silicon oxide. Also good.
  • the vertical alignment film of the second substrate using the photo-alignment film material for example, a method of irradiating the photo-alignment film with ultraviolet rays from the vertical direction to develop a pretilt angle of approximately 90 °, etc. It is done.
  • the vertical alignment film may be subjected to an alignment treatment such as rubbing treatment or ultraviolet irradiation, but it is preferable that the alignment treatment is not performed, and the vertical alignment property is merely formed. It is more preferable to express Thereby, an orientation process process can be abbreviate
  • Each picture element has two horizontal orientation control areas that divide the picture element area into approximately two equal parts.
  • the pixel electrode 13 and the common electrode 15 are provided so as to overlap each other along the arrangement direction of both horizontal alignment control regions.
  • a planar lower electrode may be provided below the first electrode 13 and the second electrode 15.
  • the first electrode 13 and the second electrode 15 include a plurality of linear portions arranged in parallel with each other with a gap therebetween.
  • the slit and the linear portion extend substantially parallel to the source bus line.
  • the width of the linear portion means the length of the linear portion in the direction orthogonal to the longitudinal direction
  • the width of the slit means the slit in the direction orthogonal to the longitudinal direction.
  • the color filter layer includes a plurality of color layers (color filters) provided corresponding to each picture element.
  • the color layer is used for color display and is formed of a transparent organic insulating film such as an acrylic resin containing a pigment.
  • Each pixel is composed of, for example, three picture elements that output light of each color of R (red), G (green), and B (blue).
  • the kind and number of the color of the picture element which comprises each pixel are not specifically limited, It can set suitably.
  • FIG. 6 is a schematic plan view illustrating the liquid crystal display device according to the first embodiment.
  • FIG. 7 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the first embodiment.
  • the ⁇ / 4 plate is disposed with its retardation plate axis shifted by 45 ° from the compensation retardation plate axis so as to sandwich the liquid crystal panel and the compensation retardation plate from above and below.
  • the phase difference plate axis of the ⁇ / 4 plate is shown.
  • the polarizing plate is arranged in such a manner as to sandwich the ⁇ / 4 plate, and the orientation of the polarizer or the analyzer of the polarizing plate is indicated as “POL axis”.
  • POL axis Such a positional relationship among the compensation retardation plate, the ⁇ / 4 plate, and the polarizing plate is the same in the later-described embodiments (FIGS. 9, 11, 13, and 18).
  • the pixel layout using the TBA type 18 ⁇ m pitch comb-teeth electrodes is used to positively form four domains, so that the center portion of the pixel electrode 13 (the vertical division portion of the photo-alignment) is applied to the pixel shown in FIG.
  • the orientation was controlled in the direction of the arrow. That is, as shown in FIG. 6, the liquid crystal molecules in the display region surrounded by the one-dot chain line are aligned in the direction indicated by the one-dot chain line by the photo-alignment film, and the liquid crystal molecules in the display region surrounded by the broken line are aligned. Orientation is in the direction indicated by the dashed arrow.
  • the compensation retardation plate axis is substantially parallel to the direction in which the photo-alignment film of the first substrate aligns the liquid crystal molecules below the threshold voltage when the substrate main surface is viewed in plan.
  • the orientation direction shown in FIG. 6 is also referred to as a domain axis in this specification.
  • the space between the pair of comb electrodes at this time changes from 4.5 ⁇ m to 6 ⁇ m at the center toward the pixel end.
  • L / S is 3 ⁇ m / 5.5 ⁇ m on average in one pixel, and this is constant between pixels.
  • the tilt angle for controlling the parallel orientation was set at 3 °. Since the retardation of the panel is parallel on one side, the retardation at the off time is 206 nm.
  • the additional retardation plate may be placed either above or below the liquid crystal panel, and a 360 nm retardation plate is arranged so that the total wavelength is 1 (560 nm). Under these conditions, the transmittance of circularly polarized light and linearly polarized light was simulated. The transmittance in the first embodiment was 22.5%.
  • FIG. 8 is a schematic plan view showing the liquid crystal display device according to the second embodiment.
  • FIG. 9 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the second embodiment.
  • L / S 3 ⁇ m / 5.5 ⁇ m.
  • it concerns a circularly polarized light system, and the transmittance T (%) was as high as 20.0%.
  • the wavelength of transmitted light in the simulation is 550.0 nm.
  • the counter substrate has a counter electrode.
  • a hole (indicated by a white dotted line in FIG. 8) in the counter electrode, an oblique electric field is generated from the pixel electrode of the lower substrate to the upper portion, and four domains can be more actively formed.
  • the alignment control hole may be a pinhole-shaped hole used for controlling the liquid crystal in the radial alignment mode.
  • Other configurations in the second embodiment are the same as those in the first embodiment.
  • the cell thickness is 3.2 ⁇ m
  • the cell thickness and the liquid crystal used are the same in all embodiments, reference examples, and comparative examples described later.
  • FIG. 10 is a schematic plan view illustrating the liquid crystal display device according to the third embodiment.
  • FIG. 11 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the third embodiment.
  • L / S 3 ⁇ m / 5.5 ⁇ m.
  • the transmittance T (%) was as high as 21.8%.
  • the wavelength of transmitted light in the simulation is 550.0 nm.
  • comb-teeth electrodes with a pitch of 18 ⁇ m are used, but the pixel electrodes are laid out so as to be symmetrical above and below the pixels. For this reason, the balance of four domains is good.
  • Other configurations in the third embodiment are the same as those in the first embodiment.
  • FIG. 12 is a schematic plan view showing the liquid crystal display device according to the fourth embodiment.
  • FIG. 13 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the fourth embodiment.
  • the transmittance T (%) was as high as 22.4%.
  • the wavelength of transmitted light in the simulation is 550.0 nm.
  • the fourth embodiment comb-shaped electrodes with a pitch of 18 ⁇ m are used, and the pixel electrodes are laid out so that the pixel electrodes are symmetrical above and below the pixels.
  • the configuration of the fourth embodiment is the same as that of the second embodiment except that there is no electrode on the counter substrate side of the second embodiment in which four domains are balanced. Other configurations in the fourth embodiment are the same as those in the first embodiment. In both Embodiments 3 and 4, multi-domaining in four directions is achieved for improved transmittance and viewing angle.
  • the optical film configuration of the circularly polarizing plate is as described above.
  • one retardation plate is disposed on the light incident side of the liquid crystal for liquid crystal compensation cancellation, and the liquid crystal and the retardation plate are arranged.
  • ⁇ / 4 plates (45 ° shifted from the compensation retardation plate axis and intersecting at right angles) are arranged above and below, respectively, and a linear polarizing plate is arranged so as to sandwich the ⁇ / 4 plate.
  • FIG. 14 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the fifth embodiment.
  • Embodiment 5 is the same as the configuration of Embodiment 1 except that the orientation of the POL axis is changed and the circular polarization system is changed to a linear polarization system.
  • FIG. 6 a schematic plan view showing the liquid crystal display device of Embodiment 5 is shown in FIG. This is the same as in the first embodiment (FIG. 6).
  • the transmittance T (%) was as high as 20.7%.
  • the wavelength of transmitted light in the simulation is 550.0 nm.
  • the orientation of the polarizer in the linearly polarizing plate is 135.0 °
  • the orientation of the analyzer is 45.0 °.
  • FIG. 15 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the sixth embodiment.
  • the sixth embodiment is the same as the configuration of the second embodiment except that the orientation of the POL axis is changed and the circularly polarized light system is changed to a linearly polarized light system.
  • a schematic plan view showing the liquid crystal display device of the sixth embodiment is shown in FIG. This is the same as in the second embodiment (FIG. 8).
  • the transmittance T (%) was as high as 20.2%.
  • the wavelength of transmitted light in the simulation is 550.0 nm.
  • the orientation of the polarizer in the linearly polarizing plate is 135.0 °
  • the orientation of the analyzer is 45.0 °.
  • FIG. 16 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the seventh embodiment.
  • Embodiment 7 is the same as the configuration of Embodiment 3 except that the direction of the POL axis is changed and the circular polarization system is changed to a linear polarization system.
  • the schematic plan view showing the liquid crystal display device of Embodiment 7 is shown in FIG. This is the same as in Embodiment 3 (FIG. 10).
  • the transmittance T (%) was as high as 21.4%.
  • the wavelength of transmitted light in the simulation is 550.0 nm.
  • the orientation of the polarizer in the linearly polarizing plate is 135.0 °
  • the orientation of the analyzer is 45.0 °.
  • FIG. 17 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the eighth embodiment.
  • Embodiment 8 is the same as the configuration of Embodiment 4 except that the orientation of the POL axis is changed and the circular polarization system is changed to a linear polarization system.
  • FIG. 12 a schematic plan view showing a liquid crystal display device of Embodiment 8 is shown in FIG. This is the same as in the fourth embodiment (FIG. 12).
  • the transmittance T (%) was as high as 19.4%.
  • the wavelength of transmitted light in the simulation is 550.0 nm. As shown in FIG.
  • the orientation of the polarizer in the linearly polarizing plate is 135.0 °, and the orientation of the analyzer is 45.0 °.
  • the transmittance of circularly polarized light and linearly polarized light is almost the same, but this is achieved more effectively in the 4-domain configuration, and the liquid crystal molecules have a linearly polarized light extraction efficiency. The reason is that many are aligned in the good 45 ° direction.
  • FIG. 18 and 19 are diagrams showing another arrangement example of the retardation plates.
  • FIG. 18 shows another arrangement example of the retardation plates in the circular polarization system
  • FIG. 19 shows another arrangement example of the retardation plates in the linear polarization system.
  • the retardation plates may be arranged such that the retardation plate axis is in the 0-180 ° azimuth perpendicular to the domain axis.
  • the compensation retardation plate axis is substantially perpendicular to the direction in which the photo-alignment film of the first substrate aligns the liquid crystal molecules below the threshold voltage when the main surface of the substrate is viewed in plan.
  • a 206 nm retardation plate can be used so as to eliminate the retardation of the panel. Even if the retardation plate shaft is arranged in this manner, the effects of the present invention can be exhibited.
  • the optical film configuration itself of the circularly polarizing plate shown in FIG. 18 is the same as the optical film configuration of the circularly polarizing plate described above, and the circularly polarizing plate system has one retardation plate for liquid crystal compensation cancellation. Placed on the light incident side of the liquid crystal, ⁇ / 4 plates (45 ° shifted from the compensation retardation plate axis and intersected at right angles) above and below the liquid crystal and the retardation plate, respectively, In this structure, the ⁇ / 4 plates are sandwiched.
  • FIG. 20 is a schematic plan view showing a liquid crystal display device according to Comparative Example 1.
  • FIG. 21 is a schematic plan view showing the transmittance distribution and the like of the liquid crystal display device according to Comparative Example 1.
  • the transmittance T (%) was 19.3%.
  • Reference numeral 41 represents a glass substrate
  • reference numeral 43 represents a first electrode
  • reference numeral 45 represents a second electrode. The following also represents the same members except that the hundreds are changed.
  • FIG. 41 represents a glass substrate
  • reference numeral 43 represents a first electrode
  • reference numeral 45 represents a second electrode. The following also represents the same members except that the hundreds are changed.
  • FIG. 1 represents a glass substrate
  • reference numeral 43 represents a first electrode
  • reference numeral 45 represents a second electrode. The following also represents the same members except that the hundreds are changed
  • FIG. 22 is a schematic plan view showing a liquid crystal display device according to Comparative Example 2.
  • FIG. 23 is a schematic plan view showing the transmittance distribution and the like of the liquid crystal display device according to Comparative Example 2.
  • 24 is a schematic plan view showing a liquid crystal display device according to Reference Example 1.
  • FIG. FIG. 25 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to Reference Example 1.
  • the transmittance when the pixel layout using the TBA-type comb-teeth electrode is reduced to a high-definition pixel (from 146 ppi to 470 ppi) was calculated with LCD-Master3D manufactured by Shintec.
  • the arrangement area of the comb electrodes is reduced, and the transmittance (linearly polarized light) is drastically reduced.
  • the transmittance is greatly improved by using two domains, the viewing angle becomes poor because of almost two domains as shown in the figure below.
  • FIG. 26 is a schematic plan view showing a liquid crystal display device according to Comparative Example 3.
  • FIG. 27 is a schematic plan view showing the transmittance distribution and the like of the liquid crystal display device according to Comparative Example 3.
  • the pixel pitch is 18 ⁇ m ⁇ 54 ⁇ m
  • TBA is divided into two domains
  • L / S 3 ⁇ m / 5.5 ⁇ m.
  • it concerns a linearly polarized light system, and the transmittance T (%) was 24.0%.
  • FIG. 28 is a schematic plan view showing the transmittance distribution and the like of the liquid crystal display device according to Comparative Example 4.
  • the pixel pitch is 18 ⁇ m ⁇ 54 ⁇ m
  • TBA is made into two domains
  • L / S 3 ⁇ m / 5.5 ⁇ m.
  • it concerns a circularly polarized light system, and the transmittance T (%) was 25.2%.
  • the transmittance was simulated by circularly polarized light in a pixel having a two-domain structure in a pixel layout using a TBA type 18 ⁇ m pitch comb electrode.
  • the molecular axis at an angle of 45 ° from the absorption axis determines the transmitted light intensity
  • molecules in an orientation state deviating from the orientation are also converted into transmitted light. Because it is.
  • the transmittance is improved, the viewing angle is not improved due to the originally two domains.
  • a liquid crystal display device in MB As seen in a tablet or the like, pixels have been increased in definition and the pixel size has been reduced.
  • the transmittance can also be achieved in 4 domains, but in the 4-domain TBA of the comparative example 2 in which the pixel pitch is small, the gap is increased due to the arrangement of the comb teeth (increase in the transmission loss portion). As a result, the transmittance decreases.
  • To satisfy the transmittance with a pixel size of 18 ⁇ m pitch there are a method of forming two domains as in Comparative Example 3 and eliminating the loss part, and a method of improving the transmittance by using circularly polarized light. The viewing angle is poor because there are no four directions.
  • a horizontal (parallel) photo-alignment film is disposed on the lower substrate, and the initial alignment is divided in the vertical direction (90/270 ° azimuth). Therefore, in addition to the complementary compensation between the comb electrodes in the transverse electric field of TBA, complementary compensation is realized also in the upper and lower electrodes, so that four domains can be realized, and the transmittance is improved by circular polarization (linear polarization). However, there is an effect, but circularly polarized light is even more effective).
  • a lateral electric field is generated between the pixel electrode and the common electrode of the lower layer substrate, and in the second embodiment, the four-domain is more actively formed by the oblique electric field generated by the slit electrode of the counter substrate.
  • each embodiment of the present invention is preferably combined with an oxide semiconductor TFT.
  • the semiconductor in the thin film transistor used for the pixel electrode of the present invention is preferably an oxide semiconductor (such as indium gallium zinc composite oxide [IGZO]).
  • IGZO indium gallium zinc composite oxide
  • 29 and 30 are schematic plan views illustrating one embodiment of a thin film transistor. s represents a source, d represents a drain, and g represents a gate.
  • FIG. 29 shows the case where an amorphous silicon semiconductor layer (Si) is used, but as shown in FIG. 30, an oxide semiconductor layer OS (IGZO or the like) is used as the semiconductor layer instead of the Si semiconductor layer. It can be used suitably.
  • An oxide semiconductor shows higher carrier mobility than amorphous silicon. For this reason, the area of the transistor using the oxide semiconductor layer OS can be smaller than that of amorphous silicon in one pixel. Specifically, the size can be reduced by about 40 to 50%.
  • This miniaturization contributes as it is as an aperture ratio, so that the light transmittance per pixel can be increased. Therefore, by using the oxide semiconductor TFT, the transmittance improving effect which is the effect of the present invention can be obtained more remarkably.
  • the mainstream is about 300 ppi (pixel per inch).
  • the pixel pitch is about 30 ⁇ m.
  • IGZO As a result of the improvement of the aperture ratio by the TFT using the above, a synergistic effect is obtained with respect to the improvement of the transmittance.
  • the aperture ratio (transmittance) of 5% can be increased by reducing the area of the TFT by adopting IGZO, as shown in Table 4 below.
  • Table 4 below l ( ⁇ m) is an example of the distance (channel length) between the source s and the drain d shown in FIGS. 29 and 30, respectively, and w1 ( ⁇ m) is shown in FIG. It is an example of the length (channel width) of one side of the illustrated amorphous silicon semiconductor layer Si, and w2 ( ⁇ m) is an example of the length (channel width) of one side of the oxide semiconductor layer OS illustrated in FIG. .
  • the area ( ⁇ m 2 ) refers to the area of the TFT when the width of the source s and drain d is calculated to be 5 ⁇ m.
  • the aperture ratio refers to the ratio of the area of the opening to the pixel area in one pixel.
  • the liquid crystal display device has a certain function and effect in combination with the above-described oxide semiconductor TFT, but is driven using a known TFT element such as an amorphous silicon TFT or a polycrystalline silicon TFT. Is also possible.

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Abstract

Provided is a liquid crystal display device capable of both a high transmission rate and a wide view angle. This liquid crystal display device is a liquid crystal display device wherein: a liquid crystal layer includes liquid crystal molecules having positive dielectric anisotropy; a first substrate has an orientation control layer, a first electrode, and a second electrode; a second substrate has an orientation control layer; the orientation control layer in the first substrate orients horizontally, relative to the substrate main surface, liquid crystal molecules at less than a threshold voltage, and has, within a pixel, an orientation control area that orients liquid crystal molecules in one direction and an orientation control area that orients liquid crystal molecules in a direction different to said direction; and the orientation control layer of the second substrate orients vertically, relative to the substrate main surface, liquid crystal molecules at less than the threshold voltage.

Description

液晶表示装置Liquid crystal display
本発明は、液晶表示装置に関する。より詳しくは、シンプルな画素構造で高透過率と広視野角とを両立することができる液晶表示装置に関するものである。 The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device that can achieve both high transmittance and a wide viewing angle with a simple pixel structure.
液晶表示装置は、一対のガラス基板等に液晶表示素子を挟持して構成され、薄型で軽量かつ低消費電力といった特長を活かして、モバイル用途や各種のモニター、テレビ等、日常生活やビジネスに欠かすことのできないものとなっている。近年においては、電子ブック、フォトフレーム、ＩＡ（産業機器）、ＰＣ（パーソナルコンピュータ）、タブレットＰＣ、スマートフォン用途等に幅広く採用されている。これらの用途において、液晶層の光学特性を変化させるための電極配置や基板の設計に係る各種モードの液晶表示パネルが検討されている。 A liquid crystal display device is configured by sandwiching a liquid crystal display element between a pair of glass substrates, etc., and is indispensable for daily life and business, such as mobile applications, various monitors, and televisions, taking advantage of its thin, lightweight, and low power consumption. It is impossible. In recent years, it has been widely used for electronic books, photo frames, IA (industrial equipment), PCs (personal computers), tablet PCs, smartphones, and the like. In these applications, liquid crystal display panels of various modes related to electrode arrangement and substrate design for changing the optical characteristics of the liquid crystal layer have been studied.
例えば、液晶を駆動する電極が形成されたＴＦＴ基板とカラーフィルタが形成された対向基板との間に誘電異方性が正の液晶を挟持した液晶表示装置であって、前記ＴＦＴ基板には、画素電極及びコモン電極が形成され、前記画素電極と前記コモン電極によって１画素が複数の領域に区画され、前記液晶の初期配向は、前記ＴＦＴ基板あるいは前記対向基板に対して垂直方向であり、前記画素電極と前記コモン電極の間に電圧を印加することによって液晶分子の向きを変えることが出来、前記電圧を印加した時の前記液晶分子の向きは、前記対向基板に形成された突起によって前記複数の領域毎に制御され、前記電圧を印加したときの、前記複数の領域における前記液晶分子の向きは、前記複数の領域毎に異なる液晶表示装置が開示されている（例えば、特許文献１参照。）。 For example, a liquid crystal display device in which a liquid crystal with positive dielectric anisotropy is sandwiched between a TFT substrate on which an electrode for driving liquid crystal is formed and a counter substrate on which a color filter is formed, and the TFT substrate includes: A pixel electrode and a common electrode are formed, one pixel is partitioned into a plurality of regions by the pixel electrode and the common electrode, and an initial alignment of the liquid crystal is perpendicular to the TFT substrate or the counter substrate, The direction of the liquid crystal molecules can be changed by applying a voltage between the pixel electrode and the common electrode, and the direction of the liquid crystal molecules when the voltage is applied is determined by the protrusions formed on the counter substrate. A liquid crystal display device is disclosed in which the orientation of the liquid crystal molecules in the plurality of regions when the voltage is applied is controlled for each of the regions, and is different for each of the plurality of regions. (E.g., see Patent Document 1.).
また所定の間隙で対向する２枚の基板と、前記２枚の基板の対向面側にそれぞれ形成された電極と、前記電極上に形成された垂直配向膜と、前記間隙に封止された負の誘電異方性を有する液晶とを有する液晶表示装置において、前記電極間に電圧が印加された際に前記液晶の配向ベクトル場の特異点が所定位置に形成されるように制御する特異点制御部を有し、形成された前記特異点を少なくとも利用して前記液晶を配向制御する液晶表示装置が開示されている（例えば、特許文献２参照。）。 Also, two substrates facing each other with a predetermined gap, electrodes formed on opposite sides of the two substrates, a vertical alignment film formed on the electrodes, and a negative electrode sealed in the gap In a liquid crystal display device having a liquid crystal having a dielectric anisotropy, singular point control is performed so that a singular point of an orientation vector field of the liquid crystal is formed at a predetermined position when a voltage is applied between the electrodes. There has been disclosed a liquid crystal display device having a portion and controlling the alignment of the liquid crystal using at least the formed singular point (see, for example, Patent Document 2).
特開２００９－２１６７９３号公報JP 2009-216793 A 特開２００１－２４９３４０号公報JP 2001-249340 A
上述した特許文献１は、ＨＡＮ（Hybrid Aligned Nematic）構造（液晶が、ハイブリッド配向ネマチック液晶となる液晶表示装置の構造）での４ドメイン化による広視野角化を開示する。また、上述した特許文献２は、ＶＡ（垂直配向；Vertical Alignment）で放射配向パターンでのマルチドメイン化を開示する。 Patent Document 1 described above discloses widening of the viewing angle by four domains in a HAN (Hybrid Aligned Nematic) structure (a structure of a liquid crystal display device in which a liquid crystal is a hybrid alignment nematic liquid crystal). Further, Patent Document 2 described above discloses multi-domain formation in a radial alignment pattern by VA (vertical alignment; vertical alignment).
特許文献１では、画素電極を卍型にしているため、特に小さな画素での設計では、電極部に起因して開口率ロスになり、透過率を向上するための工夫の余地があった。また、偏光板の種類の開示もなかった。特許文献２では、ＶＡでの画素内のマルチドメイン化技術が開示されているが、特許文献１と同様に、特に小さな画素では、電極の配置により開口率が低下し、透過率を向上するための工夫の余地があった。つまり、ディスプレイの高精細化が進む中、特に小さな画素で、視野角性能を保持し、透過率を向上する技術は、未だ要望されている。 In Patent Document 1, since the pixel electrode has a bowl shape, particularly in the design with a small pixel, the aperture ratio is lost due to the electrode portion, and there is room for improvement to improve the transmittance. There was also no disclosure of the type of polarizing plate. Patent Document 2 discloses a multi-domain technique in a pixel in VA. However, as in Patent Document 1, in particular, in a small pixel, the aperture ratio is reduced due to the arrangement of electrodes, and the transmittance is improved. There was room for ingenuity. In other words, as the display becomes more sophisticated, there is still a demand for a technology that maintains viewing angle performance and improves the transmittance, particularly with small pixels.
上述したように、特に小さな画素ピッチ（例えば、１８μｍ、４７０ｐｐｉ相当）の液晶表示装置では、マルチドメイン化すると画素内の配向有効領域が極端に低下し透過率が激減する。透過率低下を防止するには、例えば２ドメイン化することが挙げられるが、これにより視野角特性が悪化する。例えば、ＴＢＡ（Transverse Bend Alignment）の高精細画素において透過率を重視すると２ドメイン化され、視野角特性が悪くなる。 As described above, in a liquid crystal display device having a particularly small pixel pitch (e.g., 18 μm, equivalent to 470 ppi), when the multi-domain structure is used, the effective alignment region in the pixel is extremely lowered and the transmittance is drastically reduced. In order to prevent the decrease in transmittance, for example, two domains can be mentioned, but this deteriorates the viewing angle characteristics. For example, if the transmittance is emphasized in a high-definition pixel of TBA (Transverse Bend す る と Alignment), it is divided into two domains and the viewing angle characteristic is deteriorated.
本発明は、上記現状に鑑みてなされたものであり、高透過率と広視野角とを両立することができる液晶表示装置を提供することを目的とするものである。 The present invention has been made in view of the above situation, and an object of the present invention is to provide a liquid crystal display device capable of achieving both high transmittance and a wide viewing angle.
本発明者らは、視野角性能を保持し、透過率を向上することができる液晶パネルについて種々検討したところ、従来の液晶表示装置は、電極構造によってマルチドメイン化していたため、マルチドメイン化によって透過率が損なわれていたことを見いだした。そして、配向制御層を工夫することに着目して、透過率を充分なものとする方法を種々検討した。そして、基板主面を平面視したときの画素を縦方向に上下に分割し、それぞれ、断面視したときの、下側基板（第１基板）の配向制御層を水平配向（平行配向ともいう。）、上側基板（第２基板）の配向制御層を垂直配向のＨＡＮ構造とすることを見出した。そして、第１基板の平行配向制御領域を少なくとも２種以上とすること、すなわち、水平配向を、上下に分割した境目（中央）で光配向による初期の方向を９０°、２７０°（例えば、図６における上方向及び下方向）に設定することでドメインを上下に２分割し、かつ同方位にパネルの位相差（リターデーション又はＲｅとも言う。単位はｎｍ。）と合計１波長となる位相差板、又は、直交方向にパネルのリターデーションと同じ大きさのリターデーションの位相差板を配置すること、特に、円偏光板を用いることで、高透過率と広視野角とを両立することができることを見いだし、上記課題をみごとに解決することができることに想到し、本発明に到達したものである。 The present inventors have made various studies on a liquid crystal panel capable of maintaining viewing angle performance and improving transmittance. As a result, the conventional liquid crystal display device has been multi-domained by an electrode structure. I found that the rate was impaired. Then, paying attention to devising the orientation control layer, various methods for making the transmittance sufficient were examined. Then, the pixels when the main surface of the substrate is viewed in plan are divided vertically into the vertical direction, and the alignment control layer of the lower substrate (first substrate) when viewed in cross section is horizontal alignment (also referred to as parallel alignment). It was found that the orientation control layer of the upper substrate (second substrate) has a vertically oriented HAN structure. Then, the parallel alignment control region of the first substrate is set to at least two or more types, that is, the initial direction by optical alignment is 90 °, 270 ° (for example, FIG. 6), the domain is divided into two parts vertically, and the phase difference of the panel (also referred to as retardation or Re. The unit is nm) and the phase difference of one wavelength in total in the same direction. It is possible to achieve both high transmittance and wide viewing angle by using a plate or a retardation plate having a retardation of the same size as the retardation of the panel in the orthogonal direction, in particular, by using a circularly polarizing plate. The present inventors have found out what can be done and have conceived that the above-mentioned problems can be solved brilliantly, and have reached the present invention.
すなわち、本発明は、第１基板、第２基板、及び、両基板間に挟持される液晶層から構成される液晶セル、並びに、偏光板を備える液晶表示装置であって、上記液晶層は、正の誘電異方性をもつ液晶分子を含み、上記第１基板は、配向制御層、第１電極、及び、第２電極を有し、上記第２基板は、配向制御層を有し、上記第１基板の配向制御層は、閾値電圧未満での液晶分子を基板主面に対して水平に配向させるものであり、基板主面を平面視したときに、画素内に、一方向に液晶分子を配向させる配向制御領域と、該方向とは異なる方向に液晶分子を配向させる配向制御領域とを有し、上記第２基板の配向制御層は、閾値電圧未満での液晶分子を基板主面に対して垂直に配向させるものである液晶表示装置である。
本発明の液晶表示装置は、高精細画素で、光配向（平行）を使用し広視野角、高透過率化が可能である。 That is, the present invention is a liquid crystal cell comprising a first substrate, a second substrate, and a liquid crystal layer sandwiched between both substrates, and a polarizing plate, wherein the liquid crystal layer comprises: Liquid crystal molecules having positive dielectric anisotropy, wherein the first substrate has an orientation control layer, a first electrode, and a second electrode, the second substrate has an orientation control layer, and The alignment control layer of the first substrate aligns liquid crystal molecules below the threshold voltage horizontally with respect to the substrate main surface. When the substrate main surface is viewed in plan, the liquid crystal molecules are unidirectionally arranged in the pixel. An alignment control region for aligning liquid crystal molecules and an alignment control region for aligning liquid crystal molecules in a direction different from the direction, and the alignment control layer of the second substrate has liquid crystal molecules having a voltage lower than a threshold voltage on the main surface of the substrate. The liquid crystal display device is oriented vertically.
The liquid crystal display device of the present invention is a high-definition pixel and can achieve a wide viewing angle and high transmittance by using photo-alignment (parallel).
本発明は、例えばＬ／Ｓ（ライン／スペース）が画素間で一対の、シンプルな画素構造で開口率が向上するものであり、特に円偏光システムを用いる場合に、透過率が際立って高く、かつ上下方向に分割された初期の平行配向の効果により、４ドメイン化が可能で視野角がよい。 In the present invention, for example, L / S (line / space) is a pair of simple pixel structures, and the aperture ratio is improved with a simple pixel structure. Especially when a circular polarization system is used, the transmittance is remarkably high. In addition, due to the effect of the initial parallel orientation divided in the vertical direction, four domains can be formed and the viewing angle is good.
上記第１電極及び第２電極は、通常は複数の線状部分を含む。第１電極と第２電極との間に発生する電界により、液晶の配向を制御し、透過表示をおこなう。上記第１電極及び第２電極は、線状の電極であり、Ｌ／Ｓ（ライン／スペース）が画素間で実質的に一対であることが好ましい。また、上記第１電極及び第２電極は、線状部分を含み、上記第１電極の線状部分と第２電極の線状部分とが互いに沿っていることが好ましい。例えば、上記第１電極及び第２電極が、一対の櫛歯電極を構成するものが挙げられる。上記第１電極の線状部分と第２電極の線状部分とが互いに平行であることが、本発明の好ましい形態の一つである。本発明は、このような透過率を向上できるシンプルな画素構造で、広視野角をも達成することが可能である。 The first electrode and the second electrode usually include a plurality of linear portions. The orientation of the liquid crystal is controlled by the electric field generated between the first electrode and the second electrode, and transmissive display is performed. The first electrode and the second electrode are linear electrodes, and it is preferable that L / S (line / space) is substantially a pair between pixels. In addition, it is preferable that the first electrode and the second electrode include a linear portion, and the linear portion of the first electrode and the linear portion of the second electrode are along each other. For example, the first electrode and the second electrode may constitute a pair of comb electrodes. In one preferred embodiment of the present invention, the linear portion of the first electrode and the linear portion of the second electrode are parallel to each other. The present invention can achieve a wide viewing angle with a simple pixel structure capable of improving the transmittance.
上記第１電極及び第２電極は、閾値電圧以上で異なる電位とすることができることが好ましい。閾値電圧とは、例えば、明状態の透過率を１００％に設定したとき、５％の透過率を与える電圧値を意味する。閾値電圧以上で異なる電位とすることができるとは、閾値電圧以上で異なる電位とする駆動操作を実現できるものであればよく、これにより液晶層に印加する電界を好適に制御することが可能となる。異なる電位の好ましい上限値は、例えば２０Ｖである。異なる電位とすることができる構成としては、例えば、第１電極及び第２電極のうち、一方の電極をあるＴＦＴで駆動するとともに、他方の電極を、別のＴＦＴで駆動する。これにより、第１電極及び第２電極をそれぞれ異なる電位とすることができる。上記第１電極及び第２電極が、線状部分を有する場合に、線状部分の幅は、例えば２μｍ以上が好ましい。また、第１電極の線状部分と第２電極の線状部分との間の幅（本明細書中、スペースともいう。）は、例えば２～７μｍであることが好ましい。 It is preferable that the first electrode and the second electrode can have different potentials at a threshold voltage or higher. The threshold voltage means, for example, a voltage value that gives a transmittance of 5% when the transmittance in the bright state is set to 100%. The potential different from the threshold voltage can be any voltage as long as it can realize a driving operation with a potential different from the threshold voltage. This makes it possible to suitably control the electric field applied to the liquid crystal layer. Become. A preferable upper limit value of the different potential is, for example, 20V. As a configuration that can be set to different potentials, for example, one of the first electrode and the second electrode is driven by a certain TFT, and the other electrode is driven by another TFT. Thereby, the first electrode and the second electrode can be set to different potentials. In the case where the first electrode and the second electrode have a linear portion, the width of the linear portion is preferably 2 μm or more, for example. The width (also referred to as a space in this specification) between the linear portion of the first electrode and the linear portion of the second electrode is preferably 2 to 7 μm, for example.
上記第１基板の配向制御層は、光配向膜であることが好ましい。上記第２基板の配向制御層もまた、光配向膜であることが好ましい。 The alignment control layer of the first substrate is preferably a photo-alignment film. The alignment control layer of the second substrate is also preferably a photo-alignment film.
上記液晶表示装置は、第１基板及び／又は第２基板の液晶層とは反対側に位相差板を備え、上記位相差板の光軸は、基板主面を平面視したときに、第１基板の配向制御層が閾値電圧未満で液晶分子を配向させる方向と沿っており、上記位相差板の面内位相差と、上記液晶セルの閾値電圧未満での面内位相差との総和が、１波長、言い換えれば、５３０～５７０ｎｍであることが好適である。上記位相差板の光軸は、基板主面を平面視したときに、第１基板の配向制御層が閾値電圧未満で液晶分子を配向させる方向と実質的に平行であることがより好ましい。 The liquid crystal display device includes a retardation plate on a side opposite to the liquid crystal layer of the first substrate and / or the second substrate, and the optical axis of the retardation plate is the first when the substrate main surface is viewed in plan view. The orientation control layer of the substrate is along the direction in which the liquid crystal molecules are aligned at a value less than the threshold voltage, and the sum of the in-plane retardation of the retardation plate and the in-plane retardation at less than the threshold voltage of the liquid crystal cell is One wavelength, in other words, 530 to 570 nm is preferable. More preferably, the optical axis of the retardation plate is substantially parallel to the direction in which the alignment control layer of the first substrate aligns liquid crystal molecules below the threshold voltage when the substrate main surface is viewed in plan.
なお、偏光板をクロスニコルに交差させた場合、λ／２板をこの交差角から４５°ずらして設定するときは、クロスニコル黒から最大の白状態へ変化する。可視光（Ｙ値）の５５０ｎｍを基準に設計すると、２７５ｎｍがλ／２にあたる。つまりλは５５０ｎｍとなる。このことから、１波長の範囲は、その前後２０ｎｍ程度（５３０～５７０ｎｍ）が良好であり、それを外れると、黒状態にならない（コントラスト比〔ＣＲ〕が悪い）状態となる。 When the polarizing plate is crossed in crossed Nicols, the crossed Nicol black changes to the maximum white state when the λ / 2 plate is set to be shifted by 45 ° from the crossing angle. When the design is based on the visible light (Y value) of 550 nm, 275 nm corresponds to λ / 2. That is, λ is 550 nm. From this, the range of one wavelength is about 20 nm before and after that (530 to 570 nm), and if it is outside this range, it will not be black (contrast ratio [CR] is bad).
上記液晶表示装置は、第１基板及び／又は第２基板の液晶層とは反対側に位相差板を備え、上記位相差板の光軸は、基板主面を平面視したときに、第１基板の配向制御層が閾値電圧未満で液晶分子を配向させる方向と交差し、上記位相差板の面内位相差と、上記液晶セルの閾値電圧未満での面内位相差とが、略同一であることもまた好ましい。
上記位相差板の光軸は、基板主面を平面視したときに、第１基板の配向制御層が閾値電圧未満で液晶分子を配向させる方向と実質的に垂直であることが特に好ましい。 The liquid crystal display device includes a retardation plate on a side opposite to the liquid crystal layer of the first substrate and / or the second substrate, and the optical axis of the retardation plate is the first when the substrate main surface is viewed in plan view. The alignment control layer of the substrate intersects the direction in which liquid crystal molecules are aligned below the threshold voltage, and the in-plane retardation of the retardation plate is substantially the same as the in-plane retardation of the liquid crystal cell below the threshold voltage. It is also preferred that it be.
The optical axis of the retardation plate is particularly preferably substantially perpendicular to the direction in which the alignment control layer of the first substrate aligns the liquid crystal molecules below the threshold voltage when the substrate main surface is viewed in plan.
上記位相差板としては、例えば、液晶パネルの入光側の補償用位相差板が好適なものとして挙げられる。例えば、液晶パネルの入光側に上記位相差板が１つ配置され、該液晶パネル及び該位相差板を上下から挟むようにλ／４板が配置され、当該λ／４板を挟むかたちで偏光板が配置されることが好ましい。
上記面内位相差の定義としては、ｘｙ方向の複屈折×ギャップｄ（ｚ方向）の値を指し、通常はパネルではＲｅ＝ｄΔｎで表される。 As the retardation plate, for example, a compensation retardation plate on the light incident side of the liquid crystal panel is preferable. For example, one retardation plate is disposed on the light incident side of the liquid crystal panel, a λ / 4 plate is disposed so as to sandwich the liquid crystal panel and the retardation plate from above and below, and the λ / 4 plate is sandwiched. A polarizing plate is preferably disposed.
The definition of the in-plane retardation indicates a value of birefringence in the xy direction × gap d (z direction), and is usually represented by Re = dΔn in the panel.
上記第１電極と第２電極との間隔は、基板主面を平面視したときに、上記配向制御領域間の境目から遠ざかるほど大きくなることが好ましい。これにより、視野角特性を更に向上することができる。 It is preferable that the distance between the first electrode and the second electrode increases as the distance from the boundary between the orientation control regions increases when the main surface of the substrate is viewed in plan. Thereby, viewing angle characteristics can be further improved.
上記第２基板は、第３電極を有し、上記第３電極は、面状であり、配向制御用の穴があることが好ましい。これにより、視野角特性を更に向上することができる。 The second substrate has a third electrode, and the third electrode is preferably planar and has a hole for orientation control. Thereby, viewing angle characteristics can be further improved.
本発明の液晶表示装置における第２基板は、更に、第３電極を含むものであってもよい。これにより、第３電極と、第１電極との間で効果的に電界を発生させることができる。
上記第２基板は、配向規制構造を有してもよい。これにより、液晶分子の配向の安定性を向上することができる。 The second substrate in the liquid crystal display device of the present invention may further include a third electrode. Thereby, an electric field can be effectively generated between the third electrode and the first electrode.
The second substrate may have an alignment regulation structure. Thereby, the stability of the alignment of the liquid crystal molecules can be improved.
上記配向規制構造の好適な具体例としては、上記第３電極に形成された開口、上記第３電極上に形成された突起が挙げられる。
上記第２基板は、第３電極を有し、該第３電極は、面状であり、配向制御用の穴があることが特に好ましい。 Preferable specific examples of the alignment regulating structure include an opening formed in the third electrode and a protrusion formed on the third electrode.
The second substrate has a third electrode, and it is particularly preferable that the third electrode is planar and has an alignment control hole.
上記第１電極、及び、上記第２電極は、異なる層に形成されてもよいが、同じ絶縁層上に形成されることが好ましい。上記第１基板は、例えば、液晶層側から配向制御層、同じ層に形成された第１電極及び第２電極、並びに、絶縁層を有することが好適である。 The first electrode and the second electrode may be formed in different layers, but are preferably formed on the same insulating layer. The first substrate preferably includes, for example, an alignment control layer from the liquid crystal layer side, first and second electrodes formed in the same layer, and an insulating layer.
上記第１電極は、画素電極であり、上記第２電極は、共通電極であることが好ましい。 Preferably, the first electrode is a pixel electrode, and the second electrode is a common electrode.
上記第１基板は、第４電極を更に有してもよく、上記液晶層は、少なくとも上記第１電極、上記第２電極、上記第３電極、及び、上記第４電極によって生じる電界により駆動されてもよい。上記第４電極は、面状であることが好ましい。これにより、第４電極と、他の電極との間で効果的に電界を発生させることができる。 The first substrate may further include a fourth electrode, and the liquid crystal layer is driven by an electric field generated by at least the first electrode, the second electrode, the third electrode, and the fourth electrode. May be. The fourth electrode is preferably planar. Thereby, an electric field can be effectively generated between the fourth electrode and another electrode.
本発明の液晶パネルは、水平配向型の液晶パネルであってもよいが、コントラストを向上する観点からは、垂直配向型の液晶パネルであることが好ましい。なお、一般的な垂直配向型の液晶パネルは、視野角特性に改善の余地がある。それに対して、本発明の液晶パネルは、視野角特性に優れている。したがって、本発明の液晶パネルが垂直配向型の液晶パネルである場合、広視野角と高コントラストを両立することができる。 The liquid crystal panel of the present invention may be a horizontal alignment type liquid crystal panel, but is preferably a vertical alignment type liquid crystal panel from the viewpoint of improving contrast. Note that a general vertical alignment type liquid crystal panel has room for improvement in viewing angle characteristics. On the other hand, the liquid crystal panel of the present invention is excellent in viewing angle characteristics. Therefore, when the liquid crystal panel of the present invention is a vertical alignment type liquid crystal panel, both a wide viewing angle and a high contrast can be achieved.
上記液晶層は、正の誘電異方性を有する液晶分子を含むものである。液晶層は、実質的に正の誘電異方性を有する液晶分子から構成されるものであることが好ましい。 The liquid crystal layer includes liquid crystal molecules having positive dielectric anisotropy. The liquid crystal layer is preferably composed of liquid crystal molecules having substantially positive dielectric anisotropy.
本発明における上記偏光板は、円偏光板であることが好ましい。また、本発明における上記偏光板が直線偏光板であることもまた好ましい。前者によれば、透過率を向上することができる。後者によれば、視野角特性を更に向上することができる。なお、円偏光板を備える一般的な液晶パネルは、視野角特性に改善の余地がある。それに対して、本発明の液晶パネルは、視野角特性に優れている。したがって、本発明の液晶パネルが円偏光板を更に備える場合、高透過率と広視野角とを特に優れたものとすることができる。 The polarizing plate in the present invention is preferably a circular polarizing plate. Moreover, it is also preferable that the polarizing plate in the present invention is a linear polarizing plate. According to the former, the transmittance can be improved. According to the latter, the viewing angle characteristics can be further improved. Note that a general liquid crystal panel including a circularly polarizing plate has room for improvement in viewing angle characteristics. On the other hand, the liquid crystal panel of the present invention is excellent in viewing angle characteristics. Therefore, when the liquid crystal panel of the present invention further comprises a circularly polarizing plate, high transmittance and a wide viewing angle can be made particularly excellent.
なお、上記円偏光板の種類及び構造は特に限定されず、例えば、ディスプレイ分野に用いられる従来の円偏光板を用いることができる。好適には、位相差板と直線偏光板（直線偏光子）との積層体であるが、光学ピッチで螺旋構造を有する構造体（例えば、コレステリック液晶）を用いてもよい。 In addition, the kind and structure of the said circularly-polarizing plate are not specifically limited, For example, the conventional circularly-polarizing plate used for the display field | area can be used. Preferably, it is a laminate of a retardation plate and a linear polarizing plate (linear polarizer), but a structure (for example, cholesteric liquid crystal) having a helical structure at an optical pitch may be used.
また、上記直線偏光板の種類及び構造は特に限定されず、例えば、ディスプレイ分野に用いられる従来の直線偏光板を用いることができる。 Moreover, the kind and structure of the said linear polarizing plate are not specifically limited, For example, the conventional linear polarizing plate used for the display field | area can be used.
第１電極及び第２電極のライン　アンド　スペース、すなわち、線状部分、及び、スリットのそれぞれの幅は、適宜設定することができるが、通常、線状部分の幅Ｌは、１～８μｍ（好適には２～４μｍ）であり、スリットの幅Ｓは、１～８μｍ（好適には２～７μｍ）である。１画素におけるＬ／Ｓの平均値が画素間で一定であることが好ましい。また、本発明の液晶表示装置において、セルギャップｄは、２．８～４．５μｍ（好適には３．０～３．４μｍ）程度である。 The widths of the line and space of the first electrode and the second electrode, that is, the linear portion and the slit can be set as appropriate, but the width L of the linear portion is usually 1 to 8 μm (preferably 2 to 4 μm), and the slit width S is 1 to 8 μm (preferably 2 to 7 μm). It is preferable that the average value of L / S in one pixel is constant between pixels. In the liquid crystal display device of the present invention, the cell gap d is about 2.8 to 4.5 μm (preferably 3.0 to 3.4 μm).
本発明における画素は、高精細画素であることが好ましく、例えば、縦方向及び横方向の画素ピッチが１０～１５０μｍのものが好ましい。より好ましい上限値は、８０μｍである。なお、本発明の液晶表示装置は、透過型、反射型、及び、半透過型のいずれであってもよい。 The pixel in the present invention is preferably a high-definition pixel, and for example, a pixel pitch of 10 to 150 μm in the vertical and horizontal directions is preferable. A more preferable upper limit value is 80 μm. The liquid crystal display device of the present invention may be any of a transmissive type, a reflective type, and a transflective type.
本発明の液晶表示装置における上記第１基板及び第２基板の少なくとも一方は、薄膜トランジスタ素子を備え、上記薄膜トランジスタ素子は、酸化物半導体を含むことが好ましい。中でも、第１基板が備える薄膜トランジスタ素子が、酸化物半導体を含むことがより好ましい。 In the liquid crystal display device of the present invention, at least one of the first substrate and the second substrate preferably includes a thin film transistor element, and the thin film transistor element preferably includes an oxide semiconductor. Among these, the thin film transistor element included in the first substrate more preferably includes an oxide semiconductor.
本発明の液晶表示装置の構成は、液晶表示パネルを分解し、ＴＦＴアレイ基板と対向側の基板等を解析することで、明らかにすることが出来る。  The configuration of the liquid crystal display device of the present invention can be clarified by disassembling the liquid crystal display panel and analyzing the substrate opposite to the TFT array substrate.
本発明の液晶駆動装置及び液晶表示装置の構成としては、このような構成要素を必須として形成されるものである限り、その他の構成要素により特に限定されるものではなく、液晶駆動装置及び液晶表示装置に通常用いられるその他の構成を適宜適用することができる。
また、上述した各形態は、本発明の要旨を逸脱しない範囲において適宜組み合わされてもよい。 The configuration of the liquid crystal drive device and the liquid crystal display device of the present invention is not particularly limited by other components as long as such components are formed as essential, and the liquid crystal drive device and the liquid crystal display are not limited. Other configurations normally used in the apparatus can be applied as appropriate.
Moreover, each form mentioned above may be combined suitably in the range which does not deviate from the summary of this invention.
本発明によれば、高透過率と広視野角とを両立することができる液晶表示装置を得ることができる。 According to the present invention, it is possible to obtain a liquid crystal display device that can achieve both high transmittance and a wide viewing angle.
実施形態１の閾値電圧未満での液晶表示装置を示す断面模式図である。FIG. 3 is a schematic cross-sectional view illustrating the liquid crystal display device with a voltage lower than the threshold voltage according to the first embodiment. 実施形態１に係る閾値電圧未満での第１基板近傍の光配向による液晶分子へのチルト角付与（配向分割）を示す模式図である。FIG. 5 is a schematic diagram showing tilt angle provision (alignment division) to liquid crystal molecules by photo-alignment in the vicinity of the first substrate at a voltage lower than the threshold voltage according to the first embodiment. 実施形態１の閾値電圧以上での液晶表示装置を示す断面模式図である。FIG. 3 is a schematic cross-sectional view showing the liquid crystal display device having a voltage equal to or higher than the threshold voltage according to the first embodiment. 実施形態１に係る閾値電圧以上での第１基板近傍の光配向による液晶分子へのチルト角付与（配向分割）を示す模式図である。FIG. 5 is a schematic diagram showing tilt angle provision (alignment division) to liquid crystal molecules by photo-alignment near the first substrate at a threshold voltage or higher according to Embodiment 1. 実施形態１の閾値電圧以上での液晶表示装置断面の透過率及び液晶配向状態を示すシミュレーション結果である。6 is a simulation result showing a transmittance and a liquid crystal alignment state of a cross section of the liquid crystal display device at a threshold voltage or higher in the first embodiment. 実施形態１に係る液晶表示装置を示す平面模式図である。1 is a schematic plan view showing a liquid crystal display device according to Embodiment 1. FIG. 実施形態１に係る液晶表示装置の透過率分布等を示す平面模式図である。3 is a schematic plan view illustrating a transmittance distribution and the like of the liquid crystal display device according to Embodiment 1. FIG. 実施形態２に係る液晶表示装置を示す平面模式図である。6 is a schematic plan view showing a liquid crystal display device according to Embodiment 2. FIG. 実施形態２に係る液晶表示装置の透過率分布等を示す平面模式図である。FIG. 6 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Embodiment 2. 実施形態３に係る液晶表示装置を示す平面模式図である。6 is a schematic plan view showing a liquid crystal display device according to Embodiment 3. FIG. 実施形態３に係る液晶表示装置の透過率分布等を示す平面模式図である。FIG. 6 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Embodiment 3. 実施形態４に係る液晶表示装置を示す平面模式図である。6 is a schematic plan view showing a liquid crystal display device according to Embodiment 4. FIG. 実施形態４に係る液晶表示装置の透過率分布等を示す平面模式図である。FIG. 6 is a schematic plan view illustrating a transmittance distribution and the like of a liquid crystal display device according to a fourth embodiment. 実施形態５に係る液晶表示装置の透過率分布等を示す平面模式図である。FIG. 10 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Embodiment 5. 実施形態６に係る液晶表示装置の透過率分布等を示す平面模式図である。FIG. 10 is a schematic plan view illustrating a transmittance distribution and the like of a liquid crystal display device according to Embodiment 6. 実施形態７に係る液晶表示装置の透過率分布等を示す平面模式図である。FIG. 10 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Embodiment 7. 実施形態８に係る液晶表示装置の透過率分布等を示す平面模式図である。10 is a schematic plan view illustrating a transmittance distribution and the like of a liquid crystal display device according to Embodiment 8. FIG. 位相差板の別の配置例を示す図である。It is a figure which shows another example of arrangement | positioning of a phase difference plate. 位相差板の別の配置例を示す図である。It is a figure which shows another example of arrangement | positioning of a phase difference plate. 比較例１に係る液晶表示装置を示す平面模式図である。6 is a schematic plan view showing a liquid crystal display device according to Comparative Example 1. FIG. 比較例１に係る液晶表示装置の透過率分布等を示す平面模式図である。6 is a schematic plan view showing a transmittance distribution and the like of a liquid crystal display device according to Comparative Example 1. FIG. 比較例２に係る液晶表示装置を示す平面模式図である。10 is a schematic plan view showing a liquid crystal display device according to Comparative Example 2. FIG. 比較例２に係る液晶表示装置の透過率分布等を示す平面模式図である。It is a plane schematic diagram which shows the transmittance | permeability distribution etc. of the liquid crystal display device which concerns on the comparative example 2. 参考例１に係る液晶表示装置を示す平面模式図である。6 is a schematic plan view showing a liquid crystal display device according to Reference Example 1. FIG. 参考例１に係る液晶表示装置の透過率分布等を示す平面模式図である。It is a plane schematic diagram which shows the transmittance | permeability distribution etc. of the liquid crystal display device which concerns on the reference example 1. FIG. 比較例３に係る液晶表示装置を示す平面模式図である。10 is a schematic plan view showing a liquid crystal display device according to Comparative Example 3. FIG. 比較例３に係る液晶表示装置の透過率分布等を示す平面模式図である。It is a plane schematic diagram which shows the transmittance | permeability distribution etc. of the liquid crystal display device which concerns on the comparative example 3. 比較例４に係る液晶表示装置の透過率分布等を示す平面模式図である。It is a plane schematic diagram which shows the transmittance | permeability distribution etc. of the liquid crystal display device which concerns on the comparative example 4. 薄膜トランジスタの一形態を示す平面模式図である。1 is a schematic plan view illustrating one embodiment of a thin film transistor. 薄膜トランジスタの一形態を示す平面模式図である。1 is a schematic plan view illustrating one embodiment of a thin film transistor.
以下に実施形態を掲げ、本発明を図面を参照して更に詳細に説明するが、本発明はこれらの実施形態のみに限定されるものではない。 Embodiments will be described below, and the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited only to these embodiments.
また、以下の図では、主に１個の絵素（サブ画素）のみを図示しているが、各実施形態の液晶表示装置の表示領域（画像を表示する領域）には、複数の画素がマトリクス状に設けられている。各画素は、複数（通常、３個）の絵素からなる。なお、本明細書中、画素は、絵素（サブ画素）であってもよい。また、本明細書中、水平（平行）に配向するとは、基板主面に対して水平（平行）になるように配向することを言う。また、本明細書中、方位とは、時計の３時方向を０°とし、時計回りに回転した場合の角度（°）により表す。なお、各実施形態において、特に明示しない限り、同様の機能を発揮する部材及び部分は百の位を変更した以外は同じ符号を付している。 In the following drawings, only one picture element (sub-pixel) is mainly illustrated, but a plurality of pixels are included in the display area (area for displaying an image) of the liquid crystal display device of each embodiment. It is provided in a matrix. Each pixel is composed of a plurality of (usually three) picture elements. In the present specification, the pixel may be a pixel (sub-pixel). Further, in this specification, “orienting horizontally (parallel)” means aligning horizontally (parallel) to the main surface of the substrate. Further, in this specification, the direction is represented by an angle (°) when the clock is rotated clockwise with the 3 o'clock direction of the clock set to 0 °. In each embodiment, unless otherwise specified, members and portions that exhibit the same function are denoted by the same reference numerals except that the hundreds are changed.
また本明細書及び図中、ＰＯＬ軸とは、直線偏光板の偏光子又は検光子を示す。なお、図２１、図２３、図２５、図２７、図２８中、絵素領域上の一点鎖線の両矢印は、ドメイン方向を示す。 In this specification and the drawings, the POL axis indicates a polarizer or analyzer of a linear polarizing plate. In FIG. 21, FIG. 23, FIG. 25, FIG. 27, and FIG. 28, the double-dotted arrow on the picture element region indicates the domain direction.
（実施形態１）
図１は、実施形態１の閾値電圧未満での液晶表示装置を示す断面模式図である。図２は、実施形態１に係る閾値電圧未満での第１基板近傍の光配向による液晶分子へのチルト角付与（配向分割）を示す模式図である。図３は、実施形態１の閾値電圧以上での液晶表示装置を示す断面模式図である。図４は、実施形態１に係る閾値電圧以上での第１基板近傍の光配向による液晶分子へのチルト角付与（配向分割）を示す模式図である。 (Embodiment 1)
FIG. 1 is a schematic cross-sectional view illustrating a liquid crystal display device having a voltage lower than the threshold voltage according to the first embodiment. FIG. 2 is a schematic diagram illustrating the provision of a tilt angle (alignment division) to liquid crystal molecules by photo-alignment in the vicinity of the first substrate at a voltage lower than the threshold voltage according to the first embodiment. FIG. 3 is a schematic cross-sectional view showing the liquid crystal display device at a threshold voltage or higher according to the first embodiment. FIG. 4 is a schematic diagram illustrating the provision of a tilt angle (alignment division) to liquid crystal molecules by photoalignment in the vicinity of the first substrate at a threshold voltage or higher according to the first embodiment.
実施形態１の液晶表示装置は、横電界用の駆動電極を有する第１基板１０に相当するアクティブマトリクス基板（ＴＦＴアレイ基板）と、その第１基板１０に対向し、ガラス基板２１上にカラーフィルタ（ＣＦ）層（示さず）を積層し、基板間距離を保持する為に、そのカラーフィルタ層より設置される柱状スペーサー（示さず）を有する、第２基板２０と、第１基板１０と、第２基板２０との間に挟持される液晶層３０で構成される。第１基板１０は、液晶ディスプレイの背面側に設けられ、第２基板２０は、観察者側に設けられる。第１基板１０、第２基板２０は、表示領域を取り囲むように設けられたシール材によって貼り合わされている。 The liquid crystal display device of Embodiment 1 includes an active matrix substrate (TFT array substrate) corresponding to a first substrate 10 having a drive electrode for a lateral electric field, a color filter on the glass substrate 21 facing the first substrate 10. A second substrate 20 having a columnar spacer (not shown) disposed from the color filter layer in order to laminate a (CF) layer (not shown) and maintain a distance between the substrates; The liquid crystal layer 30 is sandwiched between the second substrate 20 and the second substrate 20. The first substrate 10 is provided on the back side of the liquid crystal display, and the second substrate 20 is provided on the viewer side. The first substrate 10 and the second substrate 20 are bonded together by a sealing material provided so as to surround the display area.
実施形態１の液晶表示装置は、以下の（１）～（４）の特徴を有する。
（１）本実施形態に係る駆動電極を有する第１基板１０は、平行電界を発生する構造を有する。第１基板１０のガラス基板１１上には、ＩＺＯ（又はＩＴＯ）等を用いて、フォトリソグラフィー等で形成された、櫛歯状電極（第１電極に相当する画素電極１３及び第２電極に相当する共通電極１５）が構成される。
（２）第１基板１０に対向する、カラーフィルタを有する第２基板２０は、カラーフィルタ上をオーバーコート層（ＯＣ）で平坦化するよう構成され、そのオーバーコート層内部、又は、上部（オーバーコート層の液晶層３０側）に柱状スペーサーを有する。
（３）第１基板１０には光配向膜（平行）を、第２基板２０には垂直配向膜を使用し、第１基板１０の近傍においては、図４に示すように、光照射によって画素電極の中央で配向分割されるようにする。本実施形態の液晶表示装置は、電圧オフ時（閾値電圧未満の時）は、第１基板１０は、近傍の液晶分子を水平（平行）に配向させ、第２基板２０は、近傍の液晶分子を垂直に配向させるＨＡＮ構造をとる。液晶層には、正の誘電異方性を有する液晶分子を使用し、横電界にて駆動する。駆動用電極（画素電極である第１電極１３及び共通電極である第２電極１５）は、片側のガラス基板１１上にインジウム錫酸化物（ＩＴＯ）をスパッタリングにて厚み１４００Åで全面形成する。ＩＴＯの代わりに、インジウム酸化亜鉛物（ＩＺＯ）を用いるものであっても良い。
（４）メルク株式会社製のポジ型液晶材料（Δε＝２３）を真空注入法にて封入し、これに円偏光板を貼合し、液晶表示素子を作製した。電圧印加時の配向状態は、電極間隔の中央を対称に相補的な配向補償を得ると同時に、画素中央部の平行配向の分割部でも相補的な配向補償を行い実質的に４ドメイン化する。
本モードの名称は、４Ｄ－ＨＢＡ（４ドメイン、ハイブリットベンドアライメント）とも言う。 The liquid crystal display device of Embodiment 1 has the following features (1) to (4).
(1) The first substrate 10 having the drive electrodes according to the present embodiment has a structure that generates a parallel electric field. On the glass substrate 11 of the first substrate 10, a comb-like electrode (corresponding to the pixel electrode 13 corresponding to the first electrode and the second electrode) formed by photolithography or the like using IZO (or ITO) or the like. Common electrode 15) is configured.
(2) The second substrate 20 having a color filter facing the first substrate 10 is configured to planarize the color filter with an overcoat layer (OC), and the inside of the overcoat layer or the upper portion (over Columnar spacers are provided on the liquid crystal layer 30 side of the coating layer.
(3) A photo-alignment film (parallel) is used for the first substrate 10, and a vertical alignment film is used for the second substrate 20. In the vicinity of the first substrate 10, as shown in FIG. The orientation is divided at the center of the electrode. In the liquid crystal display device of this embodiment, when the voltage is off (when the voltage is lower than the threshold voltage), the first substrate 10 aligns neighboring liquid crystal molecules horizontally (parallel), and the second substrate 20 uses neighboring liquid crystal molecules. A HAN structure in which is vertically oriented. The liquid crystal layer uses liquid crystal molecules having positive dielectric anisotropy and is driven by a lateral electric field. The driving electrodes (the first electrode 13 that is a pixel electrode and the second electrode 15 that is a common electrode) are formed by sputtering indium tin oxide (ITO) on the glass substrate 11 on one side to a thickness of 1400 mm. Instead of ITO, indium zinc oxide (IZO) may be used.
(4) A positive type liquid crystal material (Δε = 23) manufactured by Merck Co., Ltd. was sealed by a vacuum injection method, and a circularly polarizing plate was bonded thereto to produce a liquid crystal display element. The alignment state at the time of voltage application is substantially divided into four domains by obtaining complementary alignment compensation symmetrically at the center of the electrode interval and at the same time performing complementary alignment compensation at the parallel alignment division at the center of the pixel.
The name of this mode is also called 4D-HBA (4 domain, hybrid bend alignment).
円偏光板は、右円偏光及び左円偏光のいずれか一方を透過し、他方を吸収又は反射する光学素子である。
なお、図５は、実施形態１の閾値電圧以上での液晶表示装置断面の透過率及び液晶配向状態を示すシミュレーション結果である。シミュレーションは、シンテック社製のＬＣＤ－Ｍａｓｔｅｒ３Ｄを用いて行った。Ｄは、ダイレクタを表す。 The circularly polarizing plate is an optical element that transmits one of right circularly polarized light and left circularly polarized light and absorbs or reflects the other.
FIG. 5 is a simulation result showing the transmittance and the liquid crystal alignment state of the cross section of the liquid crystal display device above the threshold voltage of the first embodiment. The simulation was performed using LCD-Master 3D manufactured by Shintech. D represents a director.
本実施形態の液晶表示装置は、液晶パネルと、液晶パネルの後方に設けられたバックライトユニット（図示せず）と、液晶パネル、及び、バックライトユニットを駆動、及び、制御する制御部（図示せず）とを備えるものであってもよい。 The liquid crystal display device of the present embodiment includes a liquid crystal panel, a backlight unit (not shown) provided behind the liquid crystal panel, and a control unit (see FIG. 5) for driving and controlling the liquid crystal panel and the backlight unit. (Not shown).
ガラス基板１１の液晶層３０側の主面上には、互いに平行な複数のゲートバスラインと、ゲートバスラインに直交する複数のソースバスラインと、スイッチング素子であり、各絵素に設けられた薄膜トランジスタ（ＴＦＴ）と、上記第１電極１３に相当し、各絵素に設けられた画素電極と、上記第２電極１５に相当し、各絵素に設けられた共通電極と、水平（平行）配向膜とが形成されている。ゲートバスライン、ソースバスラインによって区画された領域が概ね１つの絵素領域となる。 On the main surface of the glass substrate 11 on the liquid crystal layer 30 side, there are a plurality of gate bus lines parallel to each other, a plurality of source bus lines orthogonal to the gate bus lines, and switching elements, which are provided in each picture element. A thin film transistor (TFT), a pixel electrode corresponding to the first electrode 13 and provided in each pixel, a common electrode corresponding to the second electrode 15 and provided in each pixel, and horizontal (parallel) An alignment film is formed. A region divided by the gate bus line and the source bus line is approximately one picture element region.
ガラス基板２１の液晶層３０側の主面上には、カラーフィルタ層（図示せず）と、垂直配向膜とがこの順に積層されている。カラーフィルタ層と垂直配向膜との間に、第３電極に相当する対向電極が設けられていても良い。対向電極は、面状であり、少なくとも全表示領域を覆うように切れ目なく形成されている。 On the main surface of the glass substrate 21 on the liquid crystal layer 30 side, a color filter layer (not shown) and a vertical alignment film are laminated in this order. A counter electrode corresponding to the third electrode may be provided between the color filter layer and the vertical alignment film. The counter electrode has a planar shape and is formed without a cut so as to cover at least the entire display area.
垂直配向膜は、少なくとも全表示領域を覆うように切れ目なく形成されている。垂直配向膜は、近傍の液晶分子を膜表面に対して実質的に垂直方向に配向することができる。垂直配向膜の材料としては、ポリイミド等を含む有機材料を用いて形成された有機配向膜であってもよいし、シリコン酸化物等を含む無機材料を用いて形成された無機配向膜であってもよい。 The vertical alignment film is formed without a break so as to cover at least the entire display region. The vertical alignment film can align liquid crystal molecules in the vicinity in a direction substantially perpendicular to the film surface. The material of the vertical alignment film may be an organic alignment film formed using an organic material including polyimide or the like, or an inorganic alignment film formed using an inorganic material including silicon oxide. Also good.
なお、光配向膜材料を用いて第２基板の垂直配向膜を形成する方法としては、例えば、光配向膜に垂直方向から紫外線を照射して略９０°のプレチルト角を発現させる方法等が挙げられる。このように、垂直配向膜は、ラビング処理、紫外線照射等の配向処理が行われたものであってもよいが、配向処理が行われていないことが好ましく、成膜されるだけで垂直配向性を発現することがより好ましい。これにより、配向処理工程を省略でき、製造工程を簡略化できる。 In addition, as a method for forming the vertical alignment film of the second substrate using the photo-alignment film material, for example, a method of irradiating the photo-alignment film with ultraviolet rays from the vertical direction to develop a pretilt angle of approximately 90 °, etc. It is done. As described above, the vertical alignment film may be subjected to an alignment treatment such as rubbing treatment or ultraviolet irradiation, but it is preferable that the alignment treatment is not performed, and the vertical alignment property is merely formed. It is more preferable to express Thereby, an orientation process process can be abbreviate | omitted and a manufacturing process can be simplified.
各絵素は、絵素領域を略２等分する２つの水平配向制御領域を有する。画素電極１３及び共通電極１５はそれぞれ、両方の水平配向制御領域の配列方向に沿って、重畳するように設けられている。なお、本実施形態とは異なるが、第１電極１３及び第２電極１５の下層に、面状の下層電極が設けられていても良い。 Each picture element has two horizontal orientation control areas that divide the picture element area into approximately two equal parts. The pixel electrode 13 and the common electrode 15 are provided so as to overlap each other along the arrangement direction of both horizontal alignment control regions. Although different from the present embodiment, a planar lower electrode may be provided below the first electrode 13 and the second electrode 15.
そして、電位差が発生するように第１電極１３、第２電極１５に電圧を適宜印加すると、これらの電極の間には電界が発生し、液晶層３０は、この電界によって駆動（制御）される。また、これらの電極に閾値以上の電圧を印加することによって、２つの水平配向制御領域のそれぞれに、２つの電界方向が生じ、その結果、４ドメイン化されることとなる。以上より、液晶パネルにおいて、視野角特性を改善することができる。 When a voltage is appropriately applied to the first electrode 13 and the second electrode 15 so as to generate a potential difference, an electric field is generated between these electrodes, and the liquid crystal layer 30 is driven (controlled) by this electric field. . Further, by applying a voltage higher than the threshold value to these electrodes, two electric field directions are generated in each of the two horizontal alignment control regions, and as a result, four domains are formed. As described above, viewing angle characteristics can be improved in the liquid crystal panel.
第１電極１３及び第２電極１５（一対の櫛歯電極）は、隙間をあけて互いに平行に並んだ複数の線状部分を含む。スリット、及び、線状部分は、ソースバスラインと略平行に伸びている。 The first electrode 13 and the second electrode 15 (a pair of comb electrodes) include a plurality of linear portions arranged in parallel with each other with a gap therebetween. The slit and the linear portion extend substantially parallel to the source bus line.
なお、本明細書において、線状部分の幅とは、長手方向に対して直交する方向における線状部分の長さを意味し、スリットの幅とは、長手方向に対して直交する方向におけるスリットの長さを意味する。 In this specification, the width of the linear portion means the length of the linear portion in the direction orthogonal to the longitudinal direction, and the width of the slit means the slit in the direction orthogonal to the longitudinal direction. Means the length of
カラーフィルタ層は、各絵素に対応して設けられた複数の色層（カラーフィルタ）を含む。色層は、カラー表示を行うために用いられるものであり、顔料を含有するアクリル樹脂等の透明な有機絶縁膜等から形成される。各画素は、例えば、Ｒ（赤）、Ｇ（緑）、Ｂ（青）の各色光を出力する３個の絵素から構成される。なお、各画素を構成する絵素の色の種類及び数は特に限定されず、適宜設定することができる。 The color filter layer includes a plurality of color layers (color filters) provided corresponding to each picture element. The color layer is used for color display and is formed of a transparent organic insulating film such as an acrylic resin containing a pigment. Each pixel is composed of, for example, three picture elements that output light of each color of R (red), G (green), and B (blue). In addition, the kind and number of the color of the picture element which comprises each pixel are not specifically limited, It can set suitably.
図６は、実施形態１に係る液晶表示装置を示す平面模式図である。図７は、実施形態１に係る液晶表示装置の透過率分布等を示す平面模式図である。実施形態１は、画素ピッチは１８μｍ×５４μｍであり、４Ｄ－ＨＢＡに係るものであり、Ｌ／Ｓ＝３μｍ／５．５μｍである。また、円偏光システムに係るものであり、透過率Ｔ（％）は、２２．５％と高いものであった。また、シミュレーションにおける透過光の波長は５５０．０ｎｍである。
図７では、円偏光板の位相差板に関して、液晶パネルの入光側に配置した場合の補償用位相差板の位相差板軸（補償用位相差板軸）を示している。また、実施形態１では該液晶パネル及び該補償用位相差板を上下から挟むようにλ／４板がその位相差板軸を補償用位相差板軸から４５°ずらして配置されるところ、当該λ／４板の位相差板軸を示している。更に、実施形態１では当該λ／４板を挟むかたちで偏光板が配置されるところ、当該偏光板の偏光子又は検光子の方位を「ＰＯＬ軸」として示す。このような補償用位相差板、λ／４板及び偏光板の配置関係は、後述する実施形態等（図９、図１１、図１３、図１８）においても同様である。 FIG. 6 is a schematic plan view illustrating the liquid crystal display device according to the first embodiment. FIG. 7 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the first embodiment. In the first embodiment, the pixel pitch is 18 μm × 54 μm, and it relates to 4D-HBA, and L / S = 3 μm / 5.5 μm. Moreover, it is based on a circularly polarized light system, and the transmittance T (%) was as high as 22.5%. The wavelength of transmitted light in the simulation is 550.0 nm.
FIG. 7 shows the retardation plate axis (compensation retardation plate axis) of the compensation retardation plate when arranged on the light incident side of the liquid crystal panel with respect to the retardation plate of the circularly polarizing plate. In the first embodiment, the λ / 4 plate is disposed with its retardation plate axis shifted by 45 ° from the compensation retardation plate axis so as to sandwich the liquid crystal panel and the compensation retardation plate from above and below. The phase difference plate axis of the λ / 4 plate is shown. Furthermore, in the first embodiment, the polarizing plate is arranged in such a manner as to sandwich the λ / 4 plate, and the orientation of the polarizer or the analyzer of the polarizing plate is indicated as “POL axis”. Such a positional relationship among the compensation retardation plate, the λ / 4 plate, and the polarizing plate is the same in the later-described embodiments (FIGS. 9, 11, 13, and 18).
実施形態１では、ＴＢＡ型の１８μｍピッチの櫛歯電極を使用した画素レイアウトで積極的に４ドメイン化するため画素電極１３の中央部（光配向の上下分割部）から図７に示した画素上の矢印の方向に向かって配向制御を実施した。すなわち、図６に示したように、光配向膜により、一点鎖線で囲まれた表示領域の液晶分子を一点鎖線の矢印で示した方向に配向させ、破線で囲まれた表示領域の液晶分子を破線の矢印で示した方向に配向させる。ここで、補償用位相差板軸は、基板主面を平面視したときに、第１基板の光配向膜が閾値電圧未満で液晶分子を配向させる方向と実質的に平行である。このように図６で示した配向方向を、本明細書中、ドメイン軸とも言う。また、一対の櫛歯電極（第１電極１３及び第２電極１５から構成される）間に電界を発生させることにより、閾値電圧以上において図７に示したように液晶分子を配向させ、４ドメイン化することができる。 In the first embodiment, the pixel layout using the TBA type 18 μm pitch comb-teeth electrodes is used to positively form four domains, so that the center portion of the pixel electrode 13 (the vertical division portion of the photo-alignment) is applied to the pixel shown in FIG. The orientation was controlled in the direction of the arrow. That is, as shown in FIG. 6, the liquid crystal molecules in the display region surrounded by the one-dot chain line are aligned in the direction indicated by the one-dot chain line by the photo-alignment film, and the liquid crystal molecules in the display region surrounded by the broken line are aligned. Orientation is in the direction indicated by the dashed arrow. Here, the compensation retardation plate axis is substantially parallel to the direction in which the photo-alignment film of the first substrate aligns the liquid crystal molecules below the threshold voltage when the substrate main surface is viewed in plan. Thus, the orientation direction shown in FIG. 6 is also referred to as a domain axis in this specification. Further, by generating an electric field between a pair of comb electrodes (consisting of the first electrode 13 and the second electrode 15), the liquid crystal molecules are aligned as shown in FIG. Can be
この際の一対の櫛歯電極間のスペースは、画素端部に向かって中央が４．５μｍから６μｍまで変化する。実施形態１では、Ｌ／Ｓは、１画素において平均して、３μｍ／５．５μｍであり、これは画素間で一定である。
平行配向の制御のためのチルト角は３°で設定した。パネルのリターデーションは、片側が平行配向のためオフ時でのリターデーションは２０６ｎｍとなる。追加する位相差板（補償用位相差板）の配置位置は液晶パネルの上下のどちらでもよく、合計１波長（５６０ｎｍ）となるように３６０ｎｍの位相差板を配置した。
本条件で円偏光、直線偏光での透過率のシミュレーションを実施した。実施形態１における透過率は、２２．５％であった。 The space between the pair of comb electrodes at this time changes from 4.5 μm to 6 μm at the center toward the pixel end. In the first embodiment, L / S is 3 μm / 5.5 μm on average in one pixel, and this is constant between pixels.
The tilt angle for controlling the parallel orientation was set at 3 °. Since the retardation of the panel is parallel on one side, the retardation at the off time is 206 nm. The additional retardation plate (compensation retardation plate) may be placed either above or below the liquid crystal panel, and a 360 nm retardation plate is arranged so that the total wavelength is 1 (560 nm).
Under these conditions, the transmittance of circularly polarized light and linearly polarized light was simulated. The transmittance in the first embodiment was 22.5%.
（実施形態２）
図８は、実施形態２に係る液晶表示装置を示す平面模式図である。図９は、実施形態２に係る液晶表示装置の透過率分布等を示す平面模式図である。実施形態２は、画素ピッチは１８μｍ×５４μｍであり、４Ｄ－ＨＢＡに係るものであり、Ｌ／Ｓ＝３μｍ／５．５μｍである。また、円偏光システムに係るものであり、透過率Ｔ（％）は、２０．０％と高いものであった。また、シミュレーションにおける透過光の波長は５５０．０ｎｍである。 (Embodiment 2)
FIG. 8 is a schematic plan view showing the liquid crystal display device according to the second embodiment. FIG. 9 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the second embodiment. In the second embodiment, the pixel pitch is 18 μm × 54 μm and relates to 4D-HBA, and L / S = 3 μm / 5.5 μm. Moreover, it concerns a circularly polarized light system, and the transmittance T (%) was as high as 20.0%. The wavelength of transmitted light in the simulation is 550.0 nm.
実施形態２では、対向基板が対向電極を有する。対向電極に穴（図８において、白抜きの点線で示す。）をあけることで、下側基板の画素電極から上部へも斜め電界が発生し、より積極的に４ドメイン化できている。なお、配向制御用の穴は、放射配向モードの液晶の制御用に使用するピンホール形状の穴であってもよい。
実施形態２におけるその他の構成は、実施形態１と同様である。
なお、実施形態１及び実施形態２において、セル厚は３．２μｍ、使用液晶はメルク社製のポジ型液晶（正の誘電異方性をもつ液晶分子から構成される）、△ε＝２３、△ｎ＝０．１２を使用した。後述するすべての実施形態、参考例、比較例においても、セル厚及び使用液晶は同様である。 In Embodiment 2, the counter substrate has a counter electrode. By forming a hole (indicated by a white dotted line in FIG. 8) in the counter electrode, an oblique electric field is generated from the pixel electrode of the lower substrate to the upper portion, and four domains can be more actively formed. The alignment control hole may be a pinhole-shaped hole used for controlling the liquid crystal in the radial alignment mode.
Other configurations in the second embodiment are the same as those in the first embodiment.
In the first and second embodiments, the cell thickness is 3.2 μm, the liquid crystal used is a positive liquid crystal (made of liquid crystal molecules having positive dielectric anisotropy) manufactured by Merck, Δε = 23, Δn = 0.12 was used. The cell thickness and the liquid crystal used are the same in all embodiments, reference examples, and comparative examples described later.
（実施形態３）
図１０は、実施形態３に係る液晶表示装置を示す平面模式図である。図１１は、実施形態３に係る液晶表示装置の透過率分布等を示す平面模式図である。実施形態３は、画素ピッチは１８μｍ×５４μｍであり、４Ｄ－ＨＢＡに係るものであり、Ｌ／Ｓ＝３μｍ／５．５μｍである。また、円偏光システムに係るものであり、透過率Ｔ（％）は、２１．８％と高いものであった。また、シミュレーションにおける透過光の波長は５５０．０ｎｍである。
実施形態３では、１８μｍピッチの櫛歯電極を使用するが、画素電極は画素の上下で対称的になるように画素レイアウトしている。このため４ドメイン化のバランスがよい。
実施形態３におけるその他の構成は、実施形態１と同様である。 (Embodiment 3)
FIG. 10 is a schematic plan view illustrating the liquid crystal display device according to the third embodiment. FIG. 11 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the third embodiment. In the third embodiment, the pixel pitch is 18 μm × 54 μm, which is related to 4D-HBA, and L / S = 3 μm / 5.5 μm. Moreover, it concerns a circularly polarized light system, and the transmittance T (%) was as high as 21.8%. The wavelength of transmitted light in the simulation is 550.0 nm.
In the third embodiment, comb-teeth electrodes with a pitch of 18 μm are used, but the pixel electrodes are laid out so as to be symmetrical above and below the pixels. For this reason, the balance of four domains is good.
Other configurations in the third embodiment are the same as those in the first embodiment.
（実施形態４）
図１２は、実施形態４に係る液晶表示装置を示す平面模式図である。図１３は、実施形態４に係る液晶表示装置の透過率分布等を示す平面模式図である。実施形態４は、画素ピッチは１８μｍ×５４μｍであり、４Ｄ－ＨＢＡに係るものであり、Ｌ／Ｓ＝３μｍ／５．５μｍである。また、円偏光システムに係るものであり、透過率Ｔ（％）は、２２．４％と高いものであった。また、シミュレーションにおける透過光の波長は５５０．０ｎｍである。
実施形態４でも同様に、１８μｍピッチの櫛歯電極を使用し、画素電極は画素の上下で対称的になるように画素レイアウトしている。なお、実施形態４の構成は、４ドメイン化のバランスをとった実施形態２の対向基板側の電極のない以外は、実施形態２と同様のものである。
実施形態４におけるその他の構成は、実施形態１と同様である。
実施形態３、４ともに透過率の向上、及び視野角のための４方向のマルチドメイン化ができている。
なお、円偏光板の光学フィルム構成は上述した通りであり、円偏光板システムは、液晶の補償キャンセル用に１枚の位相差板を液晶の入光側に配置し、該液晶及び位相差板の上下にそれぞれλ／４板（補償用位相差板軸から４５°ずらして直角に交差）を配置し、更に直線偏光板を、当該λ／４板を挟むように配置する構造である。 (Embodiment 4)
FIG. 12 is a schematic plan view showing the liquid crystal display device according to the fourth embodiment. FIG. 13 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the fourth embodiment. In the fourth embodiment, the pixel pitch is 18 μm × 54 μm and relates to 4D-HBA, and L / S = 3 μm / 5.5 μm. Moreover, it is based on a circularly polarized light system, and the transmittance T (%) was as high as 22.4%. The wavelength of transmitted light in the simulation is 550.0 nm.
Similarly in the fourth embodiment, comb-shaped electrodes with a pitch of 18 μm are used, and the pixel electrodes are laid out so that the pixel electrodes are symmetrical above and below the pixels. The configuration of the fourth embodiment is the same as that of the second embodiment except that there is no electrode on the counter substrate side of the second embodiment in which four domains are balanced.
Other configurations in the fourth embodiment are the same as those in the first embodiment.
In both Embodiments 3 and 4, multi-domaining in four directions is achieved for improved transmittance and viewing angle.
The optical film configuration of the circularly polarizing plate is as described above. In the circularly polarizing plate system, one retardation plate is disposed on the light incident side of the liquid crystal for liquid crystal compensation cancellation, and the liquid crystal and the retardation plate are arranged. Λ / 4 plates (45 ° shifted from the compensation retardation plate axis and intersecting at right angles) are arranged above and below, respectively, and a linear polarizing plate is arranged so as to sandwich the λ / 4 plate.
（実施形態５）
図１４は、実施形態５に係る液晶表示装置の透過率分布等を示す平面模式図である。実施形態５は、ＰＯＬ軸の向きを変更し、円偏光システムを直線偏光システムに変更した以外は、実施形態１の構成と同様であり、例えば実施形態５の液晶表示装置を示す平面模式図は、実施形態１（図６）と同様である。透過率Ｔ（％）は、２０．７％と高いものであった。また、シミュレーションにおける透過光の波長は５５０．０ｎｍであり、図１４に示すように、直線偏光板における偏光子の方位が１３５．０°、検光子の方位が４５．０°である。 (Embodiment 5)
FIG. 14 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the fifth embodiment. Embodiment 5 is the same as the configuration of Embodiment 1 except that the orientation of the POL axis is changed and the circular polarization system is changed to a linear polarization system. For example, a schematic plan view showing the liquid crystal display device of Embodiment 5 is shown in FIG. This is the same as in the first embodiment (FIG. 6). The transmittance T (%) was as high as 20.7%. The wavelength of transmitted light in the simulation is 550.0 nm. As shown in FIG. 14, the orientation of the polarizer in the linearly polarizing plate is 135.0 °, and the orientation of the analyzer is 45.0 °.
（実施形態６）
図１５は、実施形態６に係る液晶表示装置の透過率分布等を示す平面模式図である。実施形態６は、ＰＯＬ軸の向きを変更し、円偏光システムを直線偏光システムに変更した以外は、実施形態２の構成と同様であり、例えば実施形態６の液晶表示装置を示す平面模式図は、実施形態２（図８）と同様である。透過率Ｔ（％）は、２０．２％と高いものであった。また、シミュレーションにおける透過光の波長は５５０．０ｎｍであり、図１５に示すように、直線偏光板における偏光子の方位が１３５．０°、検光子の方位が４５．０°である。 (Embodiment 6)
FIG. 15 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the sixth embodiment. The sixth embodiment is the same as the configuration of the second embodiment except that the orientation of the POL axis is changed and the circularly polarized light system is changed to a linearly polarized light system. For example, a schematic plan view showing the liquid crystal display device of the sixth embodiment is shown in FIG. This is the same as in the second embodiment (FIG. 8). The transmittance T (%) was as high as 20.2%. The wavelength of transmitted light in the simulation is 550.0 nm. As shown in FIG. 15, the orientation of the polarizer in the linearly polarizing plate is 135.0 °, and the orientation of the analyzer is 45.0 °.
（実施形態７）
図１６は、実施形態７に係る液晶表示装置の透過率分布等を示す平面模式図である。実施形態７は、ＰＯＬ軸の向きを変更し、円偏光システムを直線偏光システムに変更した以外は、実施形態３の構成と同様であり、例えば実施形態７の液晶表示装置を示す平面模式図は、実施形態３（図１０）と同様である。透過率Ｔ（％）は、２１．４％と高いものであった。また、シミュレーションにおける透過光の波長は５５０．０ｎｍであり、図１６に示すように、直線偏光板における偏光子の方位が１３５．０°、検光子の方位が４５．０°である。 (Embodiment 7)
FIG. 16 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the seventh embodiment. Embodiment 7 is the same as the configuration of Embodiment 3 except that the direction of the POL axis is changed and the circular polarization system is changed to a linear polarization system. For example, the schematic plan view showing the liquid crystal display device of Embodiment 7 is shown in FIG. This is the same as in Embodiment 3 (FIG. 10). The transmittance T (%) was as high as 21.4%. The wavelength of transmitted light in the simulation is 550.0 nm. As shown in FIG. 16, the orientation of the polarizer in the linearly polarizing plate is 135.0 °, and the orientation of the analyzer is 45.0 °.
（実施形態８）
図１７は、実施形態８に係る液晶表示装置の透過率分布等を示す平面模式図である。実施形態８は、ＰＯＬ軸の向きを変更し、円偏光システムを直線偏光システムに変更した以外は、実施形態４の構成と同様であり、例えば実施形態８の液晶表示装置を示す平面模式図は、実施形態４（図１２）と同様である。透過率Ｔ（％）は、１９．４％と高いものであった。また、シミュレーションにおける透過光の波長は５５０．０ｎｍであり、図１７に示すように、直線偏光板における偏光子の方位が１３５．０°、検光子の方位が４５．０°である。
ここで、実施形態２、６の場合のみ円偏光と直線偏光の透過率が、ほぼ同等となっているが、これは４ドメイン化がより上手く達成されており液晶分子が直線偏光の取り出し効率の良い４５°方向に多く並んでいることが原因である。 (Embodiment 8)
FIG. 17 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to the eighth embodiment. Embodiment 8 is the same as the configuration of Embodiment 4 except that the orientation of the POL axis is changed and the circular polarization system is changed to a linear polarization system. For example, a schematic plan view showing a liquid crystal display device of Embodiment 8 is shown in FIG. This is the same as in the fourth embodiment (FIG. 12). The transmittance T (%) was as high as 19.4%. The wavelength of transmitted light in the simulation is 550.0 nm. As shown in FIG. 17, the orientation of the polarizer in the linearly polarizing plate is 135.0 °, and the orientation of the analyzer is 45.0 °.
Here, only in the case of Embodiments 2 and 6, the transmittance of circularly polarized light and linearly polarized light is almost the same, but this is achieved more effectively in the 4-domain configuration, and the liquid crystal molecules have a linearly polarized light extraction efficiency. The reason is that many are aligned in the good 45 ° direction.
図１８及び図１９は、位相差板の別の配置例を示す図である。図１８は、円偏光システムにおける位相差板の別の配置例を示し、図１９は、直線偏光システムにおける位相差板の別の配置例を示している。
位相差板の別の配置例としては、位相差板軸がドメイン軸と直交する０－１８０°方位となるように配置するものであってもよい。ここで、補償用位相差板軸は、基板主面を平面視したときに、第１基板の光配向膜が閾値電圧未満で液晶分子を配向させる方向と実質的に垂直である。例えば、実施形態１において、図１８に示した位相差板の別配置を適用する場合は、パネルのリターデーションとうち消しあうように、２０６ｎｍの位相差板を用いることができる。このように位相差板軸を配置しても、本発明の効果を発揮することができる。
なお、図１８に示した円偏光板の光学フィルム構成自体は、上述した円偏光板の光学フィルム構成と同様であり、円偏光板システムは、液晶の補償キャンセル用に１枚の位相差板を液晶の入光側に配置し、該液晶及び位相差板の上下にそれぞれλ／４板（補償用位相差板軸から４５°ずらして直角に交差）を配置し、更に直線偏光板を、当該λ／４板を挟むように配置する構造である。 18 and 19 are diagrams showing another arrangement example of the retardation plates. FIG. 18 shows another arrangement example of the retardation plates in the circular polarization system, and FIG. 19 shows another arrangement example of the retardation plates in the linear polarization system.
As another example of the arrangement of the retardation plates, the retardation plates may be arranged such that the retardation plate axis is in the 0-180 ° azimuth perpendicular to the domain axis. Here, the compensation retardation plate axis is substantially perpendicular to the direction in which the photo-alignment film of the first substrate aligns the liquid crystal molecules below the threshold voltage when the main surface of the substrate is viewed in plan. For example, in the first embodiment, when another arrangement of the retardation plates shown in FIG. 18 is applied, a 206 nm retardation plate can be used so as to eliminate the retardation of the panel. Even if the retardation plate shaft is arranged in this manner, the effects of the present invention can be exhibited.
Note that the optical film configuration itself of the circularly polarizing plate shown in FIG. 18 is the same as the optical film configuration of the circularly polarizing plate described above, and the circularly polarizing plate system has one retardation plate for liquid crystal compensation cancellation. Placed on the light incident side of the liquid crystal, λ / 4 plates (45 ° shifted from the compensation retardation plate axis and intersected at right angles) above and below the liquid crystal and the retardation plate, respectively, In this structure, the λ / 4 plates are sandwiched.
（比較例１、２、参考例１）
図２０は、比較例１に係る液晶表示装置を示す平面模式図である。図２１は、比較例１に係る液晶表示装置の透過率分布等を示す平面模式図である。比較例１は、画素ピッチは５８μｍ×１７４μｍであり、ＴＢＡの４ドメイン化されたものであり、Ｌ／Ｓ＝３μｍ／８μｍである。また、直線偏光システムに係るものであり、透過率Ｔ（％）は、１９．３％であった。なお、参照番号４１は、ガラス基板を表し、参照番号４３は、第１電極を表し、参照番号４５は、第２電極を表す。以下も、百の位を変えた以外は同様の部材を表す。
図２２は、比較例２に係る液晶表示装置を示す平面模式図である。図２３は、比較例２に係る液晶表示装置の透過率分布等を示す平面模式図である。比較例２は、画素ピッチは１８μｍ×５４μｍであり、ＴＢＡの４ドメイン化されたものであり、Ｌ／Ｓ＝３μｍ／５．５μｍである。また、直線偏光システムに係るものであり、透過率Ｔ（％）は、１０．４％であった。
図２４は、参考例１に係る液晶表示装置を示す平面模式図である。図２５は、参考例１に係る液晶表示装置の透過率分布等を示す平面模式図である。参考例１は、画素ピッチは１８μｍ×５４μｍであり、ＴＢＡの２ドメイン化されたものであり、Ｌ／Ｓ＝３μｍ／５．５μｍである。また、直線偏光システムに係るものであり、透過率Ｔ（％）は、２５．２％であった。
ＴＢＡ型の櫛歯電極を使用した画素レイアウトを高精細画素（１４６ｐｐｉから４７０ｐｐｉ）にサイズダウンした場合の透過率を、シンテック社製ＬＣＤ－Ｍａｓｔｅｒ３Ｄで計算を実施した。
セル厚は３．２μｍ、使用液晶はメルク社製のポジ型液晶、△ε＝２３、△ｎ＝０．１２を使用した。
４ドメインでは、櫛歯電極の配置領域が少なくなり透過率（直線偏光）が激減する。
２ドメイン化することで大幅に透過率は向上するが、下図のようにほとんど２ドメインのため視野角が悪くなる。 (Comparative Examples 1 and 2 and Reference Example 1)
FIG. 20 is a schematic plan view showing a liquid crystal display device according to Comparative Example 1. FIG. 21 is a schematic plan view showing the transmittance distribution and the like of the liquid crystal display device according to Comparative Example 1. In Comparative Example 1, the pixel pitch is 58 μm × 174 μm, which is a 4-domain TBA, and L / S = 3 μm / 8 μm. Moreover, it concerns a linearly polarized light system, and the transmittance T (%) was 19.3%. Reference numeral 41 represents a glass substrate, reference numeral 43 represents a first electrode, and reference numeral 45 represents a second electrode. The following also represents the same members except that the hundreds are changed.
FIG. 22 is a schematic plan view showing a liquid crystal display device according to Comparative Example 2. FIG. 23 is a schematic plan view showing the transmittance distribution and the like of the liquid crystal display device according to Comparative Example 2. In Comparative Example 2, the pixel pitch is 18 μm × 54 μm, and four domains of TBA are formed, and L / S = 3 μm / 5.5 μm. Moreover, it concerns a linearly polarized light system, and the transmittance T (%) was 10.4%.
24 is a schematic plan view showing a liquid crystal display device according to Reference Example 1. FIG. FIG. 25 is a schematic plan view illustrating the transmittance distribution and the like of the liquid crystal display device according to Reference Example 1. In Reference Example 1, the pixel pitch is 18 μm × 54 μm, and TBA is divided into two domains, and L / S = 3 μm / 5.5 μm. Moreover, it concerns a linearly polarized light system, and the transmittance T (%) was 25.2%.
The transmittance when the pixel layout using the TBA-type comb-teeth electrode is reduced to a high-definition pixel (from 146 ppi to 470 ppi) was calculated with LCD-Master3D manufactured by Shintec.
The cell thickness was 3.2 μm, and the liquid crystal used was a positive liquid crystal manufactured by Merck & Co., Δε = 23, Δn = 0.12.
In the four domains, the arrangement area of the comb electrodes is reduced, and the transmittance (linearly polarized light) is drastically reduced.
Although the transmittance is greatly improved by using two domains, the viewing angle becomes poor because of almost two domains as shown in the figure below.
（比較例３、４）
図２６は、比較例３に係る液晶表示装置を示す平面模式図である。図２７は、比較例３に係る液晶表示装置の透過率分布等を示す平面模式図である。比較例３は、画素ピッチは１８μｍ×５４μｍであり、ＴＢＡの２ドメイン化されたものであり、Ｌ／Ｓ＝３μｍ／５．５μｍである。また、直線偏光システムに係るものであり、透過率Ｔ（％）は、２４．０％であった。 (Comparative Examples 3 and 4)
FIG. 26 is a schematic plan view showing a liquid crystal display device according to Comparative Example 3. FIG. 27 is a schematic plan view showing the transmittance distribution and the like of the liquid crystal display device according to Comparative Example 3. In Comparative Example 3, the pixel pitch is 18 μm × 54 μm, and TBA is divided into two domains, and L / S = 3 μm / 5.5 μm. Moreover, it concerns a linearly polarized light system, and the transmittance T (%) was 24.0%.
図２８は、比較例４に係る液晶表示装置の透過率分布等を示す平面模式図である。比較例４は、画素ピッチは１８μｍ×５４μｍであり、ＴＢＡの２ドメイン化されたものであり、Ｌ／Ｓ＝３μｍ／５．５μｍである。また、円偏光システムに係るものであり、透過率Ｔ（％）は、２５．２％であった。 FIG. 28 is a schematic plan view showing the transmittance distribution and the like of the liquid crystal display device according to Comparative Example 4. In Comparative Example 4, the pixel pitch is 18 μm × 54 μm, and TBA is made into two domains, and L / S = 3 μm / 5.5 μm. Moreover, it concerns a circularly polarized light system, and the transmittance T (%) was 25.2%.
ＴＢＡ型の１８μｍピッチの櫛歯電極を使用した画素レイアウトで２ドメイン構造をとる画素で円偏光により透過率のシミュレーションを実施した。
セル厚は３．２μｍ、使用液晶はメルク社製のポジ型液晶、誘電率；△ε＝２３、屈折率；△ｎ＝０．１２を使用した。 The transmittance was simulated by circularly polarized light in a pixel having a two-domain structure in a pixel layout using a TBA type 18 μm pitch comb electrode.
The cell thickness was 3.2 μm, and the liquid crystal used was a positive type liquid crystal manufactured by Merck, dielectric constant: Δε = 23, refractive index: Δn = 0.12.
なお、円偏光では、透過率が２５．２％／２４．３％＝１．０４で４％程度向上する。これは、直線偏光では吸収軸から斜め４５°方位の分子軸が透過光強度を決定しているのに対して、円偏光では、その方位からずれる配向状態の分子からも透過光に変換しているためである。
透過率は向上するが、もともと２ドメインのため視野角向上にはならない。 In the case of circularly polarized light, the transmittance is improved by about 4% at 25.2% / 24.3% = 1.04. In linearly polarized light, the molecular axis at an angle of 45 ° from the absorption axis determines the transmitted light intensity, whereas in circularly polarized light, molecules in an orientation state deviating from the orientation are also converted into transmitted light. Because it is.
Although the transmittance is improved, the viewing angle is not improved due to the originally two domains.
（性能評価）
各実施形態、比較例の性能評価結果を下記表１～表３に示す。 (Performance evaluation)
The performance evaluation results of each embodiment and comparative example are shown in Tables 1 to 3 below.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
ＭＢでの液晶表示装置はタブレットなどに見られるように画素の高精細化が実施されており、画素サイズが小さくなっている。
従来サイズの比較例１では４ドメインで透過率も達成できているが、画素ピッチの小さくなる比較例２の４ドメインのＴＢＡでは、櫛歯の配置で隙間が増加し（透過ロス部分の増加）から透過率が低下する。
１８μｍピッチの画素サイズで透過率を満足するには、比較例３のように２ドメイン化し、ロス部を無くす方法、更に円偏光を使用し透過率を向上する方法があるが、いずれもマルチドメイン化が４方向でないため視野角が悪い。
本発明の実施形態では、ドメイン領域を上下に分割するため下層の基板に水平（平行）の光配向膜を配置し、初期配向を上下方向（９０／２７０°方位）に分割している。
そのためＴＢＡの横電界での櫛歯電極間の相補的補償に加え、電極上下でも相補的補償が実現されるために４ドメイン化が可能であり、更に円偏光で透過率が向上する（直線偏光でも効果はあるが、円偏光の方が更に効果が大きい）。
実施形態１、３、４では、下層基板の画素電極、共通電極間での横電界で、実施形態２では、更に、対向基板のスリット電極による斜め電界でより積極的に、４ドメイン化されている。 In a liquid crystal display device in MB, as seen in a tablet or the like, pixels have been increased in definition and the pixel size has been reduced.
In the comparative example 1 of the conventional size, the transmittance can also be achieved in 4 domains, but in the 4-domain TBA of the comparative example 2 in which the pixel pitch is small, the gap is increased due to the arrangement of the comb teeth (increase in the transmission loss portion). As a result, the transmittance decreases.
To satisfy the transmittance with a pixel size of 18 μm pitch, there are a method of forming two domains as in Comparative Example 3 and eliminating the loss part, and a method of improving the transmittance by using circularly polarized light. The viewing angle is poor because there are no four directions.
In the embodiment of the present invention, in order to divide the domain region vertically, a horizontal (parallel) photo-alignment film is disposed on the lower substrate, and the initial alignment is divided in the vertical direction (90/270 ° azimuth).
Therefore, in addition to the complementary compensation between the comb electrodes in the transverse electric field of TBA, complementary compensation is realized also in the upper and lower electrodes, so that four domains can be realized, and the transmittance is improved by circular polarization (linear polarization). However, there is an effect, but circularly polarized light is even more effective).
In the first, third, and fourth embodiments, a lateral electric field is generated between the pixel electrode and the common electrode of the lower layer substrate, and in the second embodiment, the four-domain is more actively formed by the oblique electric field generated by the slit electrode of the counter substrate. Yes.
なお、本発明の各実施形態は、酸化物半導体ＴＦＴとの組合せが好ましいものである。
例えば、本発明の画素電極に使用する薄膜トランジスタにおける半導体は、酸化物半導体（インジウムガリウム亜鉛複合酸化物〔ＩＧＺＯ〕等）が好ましい。図２９及び図３０は、薄膜トランジスタの一形態を示す平面模式図である。ｓは、ソースを示し、ｄは、ドレインを示し、ｇは、ゲートを示す。なお、図２９は、アモルファスシリコン半導体層（Ｓｉ）を用いた場合を示しているが、図３０に示したように、半導体層としてＳｉ半導体層の代わりに酸化物半導体層ＯＳ（ＩＧＺＯ等）を好適に用いることができる。酸化物半導体は、アモルファスシリコンよりも高いキャリア移動度を示す。このため酸化物半導体層ＯＳを使用したトランジスタの面積は、アモルファスシリコンより１画素に占める割合を小さくすることができる。具体的には、４０～５０％程度の小型化が可能である。 Each embodiment of the present invention is preferably combined with an oxide semiconductor TFT.
For example, the semiconductor in the thin film transistor used for the pixel electrode of the present invention is preferably an oxide semiconductor (such as indium gallium zinc composite oxide [IGZO]). 29 and 30 are schematic plan views illustrating one embodiment of a thin film transistor. s represents a source, d represents a drain, and g represents a gate. Note that FIG. 29 shows the case where an amorphous silicon semiconductor layer (Si) is used, but as shown in FIG. 30, an oxide semiconductor layer OS (IGZO or the like) is used as the semiconductor layer instead of the Si semiconductor layer. It can be used suitably. An oxide semiconductor shows higher carrier mobility than amorphous silicon. For this reason, the area of the transistor using the oxide semiconductor layer OS can be smaller than that of amorphous silicon in one pixel. Specifically, the size can be reduced by about 40 to 50%.
この小型化は、そのまま開口率として寄与するため、１画素あたりの光の透過率を高めることが可能となる。したがって、酸化物半導体ＴＦＴを用いることで、本発明の効果である透過率改善効果をより顕著に得ることができる。 This miniaturization contributes as it is as an aperture ratio, so that the light transmittance per pixel can be increased. Therefore, by using the oxide semiconductor TFT, the transmittance improving effect which is the effect of the present invention can be obtained more remarkably.
高精細化が伴う携帯端末（タブレット、スマートフォン）に関しては、３００ｐｐｉ（pixel per inch）程度が主流であり、この場合は画素ピッチとしては３０μｍ程度であり、上述した本発明の液晶モードに加え、ＩＧＺＯを使用したＴＦＴによる開口率の向上により、透過率の向上に対して相乗効果が得られる。 For mobile terminals (tablets, smartphones) with high definition, the mainstream is about 300 ppi (pixel per inch). In this case, the pixel pitch is about 30 μm. In addition to the liquid crystal mode of the present invention described above, IGZO As a result of the improvement of the aperture ratio by the TFT using the above, a synergistic effect is obtained with respect to the improvement of the transmittance.
例えば、３５μｍピッチの画素なら、下記表４に示すように、ＩＧＺＯを採用することによるＴＦＴの面積縮小で、５％の開口率（透過率）が増加できる。なお、下記表４中、ｌ（μｍ）は、図２９及び図３０にそれぞれ示したソースｓとドレインｄとの間の距離（チャネル長）の一例であり、ｗ１（μｍ）は、図２９に示したアモルファスシリコン半導体層Ｓｉの一辺の長さ（チャネル幅）の一例であり、ｗ２（μｍ）は、図３０に示した酸化物半導体層ＯＳの一辺の長さ（チャネル幅）の一例である。面積（μｍ２）は、ソースｓとドレインｄの幅を５μｍとして計算したときの、ＴＦＴの面積を言う。開口率は、１画素における画素面積に対する開口部の面積の割合を言う。 For example, if the pixel has a pitch of 35 μm, the aperture ratio (transmittance) of 5% can be increased by reducing the area of the TFT by adopting IGZO, as shown in Table 4 below. In Table 4 below, l (μm) is an example of the distance (channel length) between the source s and the drain d shown in FIGS. 29 and 30, respectively, and w1 (μm) is shown in FIG. It is an example of the length (channel width) of one side of the illustrated amorphous silicon semiconductor layer Si, and w2 (μm) is an example of the length (channel width) of one side of the oxide semiconductor layer OS illustrated in FIG. . The area (μm 2 ) refers to the area of the TFT when the width of the source s and drain d is calculated to be 5 μm. The aperture ratio refers to the ratio of the area of the opening to the pixel area in one pixel.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
更に、高精細化に伴い画素数も増加しているため、高速駆動時の高速書き込みが必要となる。ここでも高いキャリア移動度を示す酸化物半導体は高速書き込みに有利に適用することができる。
すなわち、画素の小さい高精細な液晶パネルに関しては、本発明の液晶モードと酸化物半導体ＴＦＴを用いることで、従来のアモルファスＴＦＴで作製された液晶パネルより飛躍的に性能を向上できる。 Furthermore, since the number of pixels has increased with higher definition, high-speed writing at high-speed driving is required. Again, an oxide semiconductor exhibiting high carrier mobility can be advantageously applied to high-speed writing.
That is, with respect to a high-definition liquid crystal panel with small pixels, the performance can be dramatically improved by using the liquid crystal mode and the oxide semiconductor TFT of the present invention as compared with a liquid crystal panel manufactured with a conventional amorphous TFT.
なお、本実施形態に係る液晶表示装置は、上記の酸化物半導体ＴＦＴとの組合せで一定の作用効果を奏するが、アモルファスシリコンＴＦＴや多結晶シリコンＴＦＴ等の公知のＴＦＴ素子を用いて駆動させることも可能である。 Note that the liquid crystal display device according to this embodiment has a certain function and effect in combination with the above-described oxide semiconductor TFT, but is driven using a known TFT element such as an amorphous silicon TFT or a polycrystalline silicon TFT. Is also possible.
上述した実施形態における各形態は、本発明の要旨を逸脱しない範囲において適宜組み合わされてもよい。 Each form in embodiment mentioned above may be combined suitably in the range which does not deviate from the summary of this invention.
なお、本願は、２０１１年９月２９日に出願された日本国特許出願２０１１－２１４７２５号を基礎として、パリ条約ないし移行する国における法規に基づく優先権を主張するものである。該出願の内容は、その全体が本願中に参照として組み込まれている。 The present application claims priority based on the Paris Convention or the laws and regulations in the country to which the transition is based on Japanese Patent Application No. 2011-214725 filed on September 29, 2011. The contents of the application are hereby incorporated by reference in their entirety.
１０：第１基板
１１、１１１、２１１、３１１、４１、１４１、２４１、３４１：ガラス基板
１３、１１３、２１３、３１３、４３、１４３、２４３、３４３：第１電極
１５、１１５、２１５、３１５、４５、１４５、２４５、３４５：第２電極
２０：第２基板
３０：液晶層
３１：液晶分子
Ｄ：ダイレクタ
ＯＳ：酸化物半導体層
Ｓｉ：アモルファスシリコン半導体層
ｄ：ドレイン
ｇ：ゲート
ｓ：ソース 10: First substrate 11, 111, 211, 311, 41, 141, 241, 341: Glass substrate 13, 113, 213, 313, 43, 143, 243, 343: First electrode 15, 115, 215, 315, 45, 145, 245, 345: second electrode 20: second substrate 30: liquid crystal layer 31: liquid crystal molecule D: director OS: oxide semiconductor layer Si: amorphous silicon semiconductor layer d: drain g: gate s: source

Claims (10)

  1. 第１基板、第２基板、及び、両基板間に挟持される液晶層から構成される液晶セル、並びに、偏光板を備える液晶表示装置であって、
    該液晶層は、正の誘電異方性をもつ液晶分子を含み、
    該第１基板は、配向制御層、第１電極、及び、第２電極を有し、
    該第２基板は、配向制御層を有し、
    該第１基板の配向制御層は、閾値電圧未満での液晶分子を基板主面に対して水平に配向させるものであり、基板主面を平面視したときに、画素内に、一方向に液晶分子を配向させる配向制御領域と、該方向とは異なる方向に液晶分子を配向させる配向制御領域とを有し、
    該第２基板の配向制御層は、閾値電圧未満での液晶分子を基板主面に対して垂直に配向させるものである
    ことを特徴とする液晶表示装置。     A liquid crystal cell comprising a first substrate, a second substrate, and a liquid crystal layer sandwiched between both substrates, and a polarizing plate,
    The liquid crystal layer includes liquid crystal molecules having positive dielectric anisotropy,
    The first substrate has an orientation control layer, a first electrode, and a second electrode,
    The second substrate has an orientation control layer,
    The alignment control layer of the first substrate aligns liquid crystal molecules below the threshold voltage horizontally with respect to the main surface of the substrate. When the main surface of the substrate is viewed in plan, the liquid crystal is unidirectionally arranged in the pixel. An alignment control region for aligning molecules, and an alignment control region for aligning liquid crystal molecules in a direction different from the direction,
    The liquid crystal display device, wherein the alignment control layer of the second substrate aligns liquid crystal molecules having a voltage lower than a threshold voltage perpendicularly to the main surface of the substrate.
  2. 前記第１電極及び第２電極は、線状部分を含み、
    該第１電極の線状部分と該第２電極の線状部分とが互いに沿っている
    ことを特徴とする請求項１に記載の液晶表示装置。     The first electrode and the second electrode include a linear portion,
    2. The liquid crystal display device according to claim 1, wherein the linear portion of the first electrode and the linear portion of the second electrode are along each other.
  3. 前記第１基板の配向制御層は、光配向膜である
    ことを特徴とする請求項１又は２に記載の液晶表示装置。     The liquid crystal display device according to claim 1, wherein the alignment control layer of the first substrate is a photo-alignment film.
  4. 前記液晶表示装置は、第１基板及び／又は第２基板の液晶層とは反対側に位相差板を備え、
    該位相差板の光軸は、基板主面を平面視したときに、第１基板の配向制御層が閾値電圧未満で液晶分子を配向させる方向と沿っており、
    該位相差板の面内位相差と、前記液晶セルの閾値電圧未満での面内位相差との総和が、５３０～５７０ｎｍである
    ことを特徴とする請求項１～３のいずれかに記載の液晶表示装置。     The liquid crystal display device includes a retardation plate on a side opposite to the liquid crystal layer of the first substrate and / or the second substrate,
    The optical axis of the retardation plate is along the direction in which the alignment control layer of the first substrate aligns liquid crystal molecules below the threshold voltage when the substrate main surface is viewed in plan view,
    4. The sum of an in-plane retardation of the retardation plate and an in-plane retardation at less than a threshold voltage of the liquid crystal cell is 530 to 570 nm. Liquid crystal display device.
  5. 前記液晶表示装置は、第１基板及び／又は第２基板の液晶層とは反対側に位相差板を備え、
    該位相差板の光軸は、基板主面を平面視したときに、第１基板の配向制御層が閾値電圧未満で液晶分子を配向させる方向と交差し、
    該位相差板の面内位相差と、前記液晶セルの閾値電圧未満での面内位相差とが、略同一である
    ことを特徴とする請求項１～３のいずれかに記載の液晶表示装置。     The liquid crystal display device includes a retardation plate on a side opposite to the liquid crystal layer of the first substrate and / or the second substrate,
    The optical axis of the retardation plate intersects with the direction in which the alignment control layer of the first substrate aligns liquid crystal molecules below the threshold voltage when the substrate main surface is viewed in plan view,
    4. The liquid crystal display device according to claim 1, wherein an in-plane retardation of the retardation plate and an in-plane retardation less than a threshold voltage of the liquid crystal cell are substantially the same. .
  6. 前記偏光板は、円偏光板である
    ことを特徴とする請求項１～５のいずれかに記載の液晶表示装置。     6. The liquid crystal display device according to claim 1, wherein the polarizing plate is a circularly polarizing plate.
  7. 前記偏光板は、直線偏光板である
    ことを特徴とする請求項１～５のいずれかに記載の液晶表示装置。     6. The liquid crystal display device according to claim 1, wherein the polarizing plate is a linear polarizing plate.
  8. 前記第１電極と第２電極との間隔は、基板主面を平面視したときに、前記配向制御領域間の境目から遠ざかるほど大きくなる
    ことを特徴とする請求項１～７のいずれかに記載の液晶表示装置。     8. The distance between the first electrode and the second electrode increases as the distance from the boundary between the alignment control regions increases when the main surface of the substrate is viewed in plan. Liquid crystal display device.
  9. 前記第２基板は、第３電極を有し、
    該第３電極は、面状であり、配向制御用の穴がある
    ことを特徴とする請求項１～８のいずれかに記載の液晶表示装置。     The second substrate has a third electrode;
    9. The liquid crystal display device according to claim 1, wherein the third electrode has a planar shape and has a hole for orientation control.
  10. 前記第１基板及び第２基板の少なくとも一方は、薄膜トランジスタ素子を備え、
    該薄膜トランジスタ素子は、酸化物半導体を含む
    ことを特徴とする請求項１～９のいずれかに記載の液晶表示装置。     At least one of the first substrate and the second substrate includes a thin film transistor element,
    10. The liquid crystal display device according to claim 1, wherein the thin film transistor element includes an oxide semiconductor.
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JPH09105941A (en) * 1995-10-13 1997-04-22 Stanley Electric Co Ltd Liquid crystal display device
JPH11295740A (en) * 1998-04-16 1999-10-29 Nec Corp Liquid crystal display device, manufacture and driving method thereof
JP2000267104A (en) * 1999-03-19 2000-09-29 Fujitsu Ltd Liquid crystal display device
JP2002229032A (en) * 2000-12-05 2002-08-14 Hyundai Display Technology Inc Reflection type fringe-field switching mode liquid crystal display
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