WO2010137407A1 - Liquid crystal display device - Google Patents

Liquid crystal display device Download PDF

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Publication number
WO2010137407A1
WO2010137407A1 PCT/JP2010/056215 JP2010056215W WO2010137407A1 WO 2010137407 A1 WO2010137407 A1 WO 2010137407A1 JP 2010056215 W JP2010056215 W JP 2010056215W WO 2010137407 A1 WO2010137407 A1 WO 2010137407A1
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WIPO (PCT)
Prior art keywords
liquid crystal
display device
crystal display
slit
substrate
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PCT/JP2010/056215
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French (fr)
Japanese (ja)
Inventor
齊藤全亮
小川勝也
藤岡和巧
古川智朗
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シャープ株式会社
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Publication of WO2010137407A1 publication Critical patent/WO2010137407A1/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
    • G02F1/134336—Matrix
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133707—Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G02F1/133541—Circular polarisers

Definitions

  • the present invention relates to a liquid crystal display device. More specifically, the present invention relates to a multi-domain vertical alignment type liquid crystal display device.
  • Liquid crystal display devices are used in various fields by taking advantage of their thin and light weight and low power consumption.
  • a liquid crystal display device has a structure in which a liquid crystal layer is sandwiched between a pair of substrates.
  • a vertical alignment (Vertical Alignment: VA) mode can provide a high contrast ratio.
  • VA mode liquid crystal display devices the multi-domain vertical alignment (MVA mode) liquid crystal display device described in Patent Document 1 and the like, and the continuous multi-domain radial tilt described in Patent Document 2 and the like.
  • an alignment type (Continuous Pinwheel Alignment: CPA mode) liquid crystal display device has a wide viewing angle since the alignment direction of liquid crystal molecules in one pixel is regulated in a plurality of directions.
  • the electrode for applying a voltage to the liquid crystal layer is provided with a slit (slit), or a protrusion is formed on the substrate. Then, minute protrusions are radially formed on the substrate.
  • the slit formed in the electrode is also referred to as an electrode slit.
  • the width is preferably as narrow as possible.
  • the width of the electrode slit is reduced, an electric field is also generated in the region where the electrode slit is provided, the alignment state of the liquid crystal molecules becomes unstable, and a region called disclination (line defect) is generated.
  • this region although light leakage occurs despite the reduction of the electrode slit width, the light transmittance cannot be improved, and luminance variation may occur on the display screen. In addition, this region may appear to be rough on the display screen. Such a tendency is remarkable when the electrode slit width is 7 ⁇ m or less.
  • the alignment state of the liquid crystal molecules depends not only on the tilt angle of the liquid crystal molecules but also on the tilt direction of the liquid crystal molecules, and the variation in the tilt direction of the liquid crystal molecules is caused by the generation of an electric field in the electrode slit. It is done.
  • the tilt angle of the liquid crystal molecules is the tilt angle of the liquid crystal molecules with respect to the thickness direction of the liquid crystal layer, and the tilt direction is the direction of the liquid crystal molecules when the liquid crystal molecules are projected onto the substrate surface.
  • liquid crystal molecules are aligned radially, so that the direction of light leakage due to birefringence increases, and the contrast ratio tends to be lower than that of an MVA mode liquid crystal display device. Therefore, for example, in a field where high visibility is required from the viewpoint of safety, such as in-vehicle use, further improvement in contrast ratio is required.
  • the present invention has been made in view of the above situation, and in an MVA mode liquid crystal display device, even if the width of the slit formed in the electrode is narrowed, the light transmittance is high, the luminance variation and the image
  • An object of the present invention is to provide a liquid crystal display device capable of reducing display defects such as roughness.
  • the inventors of the present invention have studied various types of MVA mode liquid crystal display devices. As a result, when the width of the slit formed in the electrode is narrowed, a region where the alignment state of the liquid crystal molecules becomes unstable is generated, and the light transmittance is reduced. We first found that a decline occurred. Then, a circularly polarizing plate is used instead of the linearly polarizing plate provided on the surface opposite to the liquid crystal layer of the pair of substrates constituting the liquid crystal display device, so that the light source does not depend on the alignment direction of the liquid crystal molecules. It is possible to transmit the light from the light source, thereby suppressing the decrease in the light transmittance, thereby reducing the variation in brightness and the roughness of the image. The present invention has been achieved.
  • the present invention is a liquid crystal display device comprising a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and an electrode for applying a voltage to the liquid crystal layer, wherein the pair of substrates One of the substrates has a plurality of protrusions that control the alignment of liquid crystal molecules in the liquid crystal layer, and the other of the pair of substrates has a plurality of slits formed in the electrodes, and the liquid crystal display
  • the apparatus is a liquid crystal display device further having a circularly polarizing plate on a surface opposite to the liquid crystal layer of the one substrate (first substrate) and the other substrate (second substrate).
  • the liquid crystal display device of the present invention is an MVA mode liquid crystal display device, and performs display by changing the retardation of the liquid crystal layer by changing the voltage applied to the liquid crystal layer.
  • the MVA mode is a negative type liquid crystal having negative dielectric anisotropy, and the liquid crystal molecules are substantially perpendicular to the substrate surface when the voltage is less than a threshold voltage (for example, no voltage is applied).
  • a threshold voltage for example, no voltage is applied.
  • This is a display mode in which liquid crystal molecules are tilted substantially horizontally with respect to the substrate surface when a voltage equal to or higher than a threshold is applied.
  • the liquid crystal molecule having negative dielectric anisotropy refers to a liquid crystal molecule having a larger dielectric constant in the minor axis direction than in the major axis direction.
  • the MVA mode has a plurality of slits formed in the electrode and a plurality of protrusions formed on the substrate surface as the structure for controlling the alignment of liquid crystal molecules.
  • the electrode is a common electrode or a pixel electrode, and is used for applying a voltage to the liquid crystal layer.
  • the slit formed in the electrode functions to bend the electric field together with the protrusion made of a dielectric. Further, by forming the protrusion on the substrate surface, the liquid crystal molecules are inclined toward the protrusion depending on the surface shape of the substrate. In this way, the alignment control of the liquid crystal molecules divided into a plurality of domains in each pixel can be realized by the action of bending the electric field and the alignment control of the liquid crystal molecules according to the surface shape of the substrate. Improvements can be realized.
  • the shape of the slit formed in the electrode is not particularly limited, for example, there is a form in which the inside of the pixel is divided into four regions by the V-shaped slit.
  • the shape of the protrusion is not particularly limited, but when the V-shaped slit is formed in the electrode, the shape of the liquid crystal molecule is determined to be a band-shaped structure arranged in a V-shape. The alignment state can be easily and uniformly regulated in the pixel.
  • the circularly polarizing plate generally comprises a linear polarizer that separates linearly polarized light from non-polarized light and a ⁇ / 4 retardation plate that converts linearly polarized light into circularly polarized light.
  • the ⁇ / 4 retardation plate is a birefringent body having a thickness direction retardation (95 to 195 nm) that is 1 ⁇ 4 of the wavelength of visible light, and preferably has a thickness direction retardation of 120 to 150 nm. It is a birefringent body.
  • the configuration of the liquid crystal display device of the present invention is not particularly limited by other components as long as such components are essential.
  • the slit width is narrowed in order to further increase the light transmittance
  • the decrease in the light transmittance due to the poor alignment of the liquid crystal molecules occurring in the vicinity of the slit is caused by the circularly polarized light described above. Compensated by the plate, the light transmittance can be increased as a result.
  • the width of the slit is preferably 15 ⁇ m or less.
  • the slit is difficult to be applied with voltage and inferior in light transmittance. Therefore, when the slit width exceeds 15 ⁇ m, the light transmittance decreases too much, and the circularly polarizing plate improves the light transmittance. Even so, the entire liquid crystal display device tends to have a low light transmittance and a low contrast ratio.
  • the lower limit of the width of the slit is not particularly limited, in the present invention, even if the roughness is 7 ⁇ m or less, which is likely to cause roughness as described above, poor alignment of the liquid crystal molecules generated in the vicinity of the slit is caused by the circularly polarizing plate.
  • a preferable lower limit value of the width of the slit is 3 ⁇ m.
  • the width of the protrusion is not particularly limited, but when the width of the protrusion is narrowed, the light transmittance tends to be improved. However, the light transmittance in each pixel is not influenced only by the width of the protrusion, but also by the light transmittance of the material itself forming the protrusion.
  • the distance between the protrusion and the slit is not particularly limited, but if the width of the protrusion and the slit is the same, the narrower the distance between the protrusion and the slit, the greater the number of pixels provided in each pixel. Transmittance decreases. In the present invention, even when the distance between the protrusion and the slit is narrow as described above, the reduction in light transmittance can be compensated for by the circularly polarizing plate.
  • the liquid crystal display device may be a transmissive liquid crystal display device or a transflective liquid crystal display device.
  • the light transmittance can be improved satisfactorily.
  • the liquid crystal display device of the present invention by providing the circularly polarizing plate on the surface opposite to the liquid crystal layer of the pair of substrates, the light transmittance is increased even if the width of the slit formed in the electrode is narrowed.
  • a liquid crystal display device with good display characteristics can be realized in which display defects such as luminance variations and image roughness are reduced.
  • FIG. 3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged.
  • FIG. 3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged.
  • FIG. 3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged.
  • FIG. 3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged.
  • FIG. 3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged.
  • FIG. 3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged.
  • FIG. 6 is a schematic plan view in which a part of a pixel according to Example 2 is enlarged.
  • 6 is a schematic plan view illustrating an alignment state of liquid crystal molecules according to Example 2.
  • FIG. 6 is a schematic plan view in which a part of a pixel according to Example 2 is enlarged.
  • 6 is a schematic plan view illustrating an alignment state of liquid crystal molecules according to Example 2.
  • FIG. 6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged.
  • FIG. 6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged.
  • FIG. 6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged.
  • FIG. 6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged.
  • FIG. 6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged.
  • FIG. 6 is a schematic plan view showing an alignment state of liquid crystal molecules according to Comparative Example 1.
  • FIG. 6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged.
  • FIG. 6 is a schematic plan view showing an alignment state of liquid crystal molecules according to Comparative Example 1.
  • FIG. 10 is a graph showing the light transmittance of the liquid crystal display device according to Example 3, and the slit width and light transmittance when the distance between the protrusion and the slit is changed to 3, 5, 8, 10, and 15 ⁇ m; This shows the relationship.
  • FIG. 21 is a graph showing the light transmittance of the liquid crystal display device according to Example 3, in which each measurement point in FIG. 20 is plotted corresponding to the area of the transmission region.
  • FIG. 1 shows a configuration of a liquid crystal display device according to this embodiment, and shows a schematic cross-sectional view of a pixel.
  • FIG. 2 shows a configuration of the liquid crystal display device according to the present embodiment, and shows a schematic plan view in which a part of a pixel is enlarged.
  • a liquid crystal display device 100 includes an array substrate 10, a counter substrate 30 provided to face the array substrate 10, and a liquid crystal provided to be sandwiched between the array substrate 10 and the counter substrate 30. Layer 20.
  • the array substrate 10 is formed on the main surface of the glass substrate 11 on the liquid crystal layer 20 side, although not shown here, a plurality of gate signal lines extending in parallel with each other, and a plurality of gate signal lines extending in parallel with each other.
  • Source signal lines, thin film transistors (TFTs) provided at intersections of gate signal lines and source signal lines.
  • the gate signal line and the source signal line are covered with a gate insulating film, and a drain electrode is formed on the gate insulating film. These are covered with an interlayer insulating film, and a pixel electrode 12 is formed on the interlayer insulating film. The pixel electrode 12 and the drain electrode are connected through a contact hole formed in the interlayer insulating film.
  • the TFT has a gate electrode connected to the gate signal line, a source electrode connected to the source signal line, and a drain electrode.
  • the pixel electrode 12 is formed to correspond to each pixel, and a plurality of slits 14 for regulating the alignment state of liquid crystal molecules is formed.
  • the slits 14 are V-shaped as shown in FIG. 2 when the substrate surface is viewed from the normal direction, and are arranged at equal intervals.
  • the width W1 of the slits 14 is preferably as narrow as possible. Specifically, the width W1 of the slit 14 is preferably 15 ⁇ m or less, more preferably 7 ⁇ m or less, and still more preferably narrowed to about 3 ⁇ m.
  • the liquid crystal layer 20 is not particularly limited as long as it is used in a VA mode liquid crystal display device.
  • a nematic liquid crystal having negative dielectric anisotropy can be used.
  • the VA mode can be typically realized by using a vertical alignment film (not shown) made of polyimide or the like formed on the surface of the array substrate 10 and the counter substrate 30 on the liquid crystal layer side.
  • a vertical alignment film (not shown) made of polyimide or the like formed on the surface of the array substrate 10 and the counter substrate 30 on the liquid crystal layer side.
  • the liquid crystal molecules in the liquid crystal layer 20 are aligned in a direction perpendicular to the surface of the alignment film, and a state where a voltage higher than the threshold is applied (on state). Then, it falls down in the horizontal direction.
  • the counter substrate 30 includes a plurality of rib-shaped protrusions 32 on the main surface of the glass substrate 31 on the liquid crystal layer 20 side, and includes a counter electrode 33 disposed to face the pixel electrode 12.
  • the plurality of protrusions 32 are for restricting the alignment state of the liquid crystal molecules.
  • the plurality of protrusions 32 are band-shaped. It is a structure and is arranged at equal intervals.
  • the width W2 of the protrusion 32 is not particularly limited. However, the narrower the width, the higher the light transmittance. However, the effect of improving the light transmittance varies depending on the material forming the protrusion 32.
  • the counter substrate 30 is, for example, a color filter substrate.
  • a color filter layer is provided on the surface of the glass substrate 31, and a counter electrode 33 is disposed via an insulating layer.
  • the counter electrode 33 is made of ITO or the like.
  • the slits 14 and the protrusions 32 are alternately arranged at equal intervals when the substrate surface is viewed from the normal direction. With such an arrangement, liquid crystal molecules are aligned in four directions as indicated by arrows a to d in each pixel, and uniform display can be obtained over a wide viewing angle.
  • circularly polarizing plates 13 and 34 are arranged on the main surface of the glass substrates 11 and 31 opposite to the liquid crystal layer 20 instead of the generally used linearly polarizing plate.
  • the liquid crystal display device 100 configured as described above is manufactured, for example, as follows. First, a method for manufacturing the array substrate 10 will be described.
  • a base coat film is formed on the main surface of the cleaned glass substrate 11, various wirings such as gate signal lines, TFTs, and the like are formed, covered with a gate insulating film, and then a drain electrode is formed. Then, the main surface of the substrate is covered with an interlayer insulating film, and a contact hole is formed in the interlayer insulating film.
  • a conductive film is formed by a method such as sputtering so as to cover the main surface of the substrate having the above structure.
  • the conductive film is formed using a conductive material with high light transmittance such as indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide.
  • ITO indium tin oxide
  • IZO indium zinc oxide
  • a resist film is formed so as to cover the obtained conductive film, and exposure / development processing is performed to form a resist pattern having a desired shape.
  • the conductive film is etched through the obtained resist pattern to form the pixel electrode 12 having the V-shaped slit 14 described above.
  • the etching process may be either a dry etching process or a wet etching process.
  • the counter substrate 30 is formed with a color filter layer (not shown) on the main surface of the glass substrate 31 and covered with an insulating layer (not shown).
  • a color filter layer (not shown)
  • an insulating layer (not shown).
  • the counter electrode 33 made of ITO is formed by sputtering or the like so as to cover the protrusion 32.
  • the array substrate 10 and the counter substrate 30 manufactured as described above are bonded together via a sealing material (sealing material), and liquid crystal is sealed between the substrates.
  • the sealing material is not particularly limited, and an ultraviolet curable resin, a thermosetting resin, or the like can be used.
  • the liquid crystal display device 100 is obtained by providing the circularly-polarizing plates 13 and 34 in the surface on the opposite side to the liquid crystal layer 20 of the glass substrates 11 and 31.
  • Example 1 The display state of the pixels was observed using the liquid crystal display device 100 in which the width W1 of the slit 14 was 5 ⁇ m, the width W2 of the protrusion 32 was 11 ⁇ m, and the distance between the protrusion 32 and the slit 14 was 15 ⁇ m.
  • the protrusion 32 is made of resin and has a light transmittance of about 40%.
  • 3 to 6 are enlarged schematic diagrams showing the state of the pixel when a voltage is applied to the liquid crystal display device 100 to switch from black display to white display.
  • each pixel has a display area 40 and a non-display area 45.
  • the area where the slits 14 and the protrusions 32 are arranged is a non-display area 45 because the light transmittance is low.
  • T 1 ⁇ T 2 ⁇ and over time in the order of T 3 ⁇ T 4, between T 1 ⁇ T 2 ⁇ T 3 ⁇ T 4 is about 1 second.
  • the width W1 of the slit 14 is as narrow as 5 ⁇ m.
  • no light leakage or the like occurred around the slit 14, and no variation in luminance was observed.
  • the states of the pixels shown in FIGS. 3 to 6 were almost the same, and almost no change was seen over time, and no roughness of the image was seen.
  • the circularly polarizing plates 13 and 34 are provided on the main surface of the glass substrates 11 and 31 opposite to the liquid crystal layer 20, and the light transmittance is transmitted by the circularly polarizing plates 13 and 34. This is thought to be due to the compensation of the decrease in.
  • Example 2 in the liquid crystal display device 100 according to the first embodiment, the light transmittance was measured by changing the width W1 of the slit 14 in increments of 1 ⁇ m between 5 and 9 ⁇ m.
  • the transmittance of light per pixel was obtained using a spectrophotometer (manufactured by TOPCON, model number BM-5). The obtained measurement results are shown in FIG.
  • the display characteristics of the liquid crystal display device 100 in the width W1 of each slit 14 were evaluated as follows. ⁇ : Brightness variation and image roughness did not occur. (Triangle
  • FIGS. 8 and 9 are a schematic plan view showing an enlarged part of a pixel when the width W1 of the slit 14 is 9 ⁇ m and a schematic plan view showing the alignment state of liquid crystal molecules.
  • FIGS. It is the plane schematic diagram which expanded a part of pixel when width W1 is 5 micrometers, and the plane schematic diagram which shows the orientation state of a liquid crystal molecule. 9 and 11, white liquid crystal molecules 50 indicate a good alignment state, and colored liquid crystal molecules 50 a indicate that alignment failure occurs.
  • the liquid crystal molecules 50 are in a good alignment state and have good display characteristics without light leakage.
  • the liquid crystal molecules 50a are poorly aligned around the slit 14, and some light leakage occurs in the slit 14. Yes.
  • the circularly polarizing plates 13 and 34 compensate for the reduction in light transmittance due to the poor alignment of the liquid crystal molecules 50a, thereby obtaining a high light transmittance as shown in FIG. 7 and occupying the entire pixel.
  • the ratio of the display area 40 became high.
  • Comparative Example 1 In the liquid crystal display device according to this comparative example, the circularly polarizing plates 13 and 34 in the liquid crystal display device 100 shown in FIGS.
  • a polyvinyl alcohol (PVA) film obtained by adsorbing and orienting an anisotropic material such as an iodine complex having dichroism was used.
  • PVA polyvinyl alcohol
  • the light transmittance and display characteristics were measured in the same manner as in Example 2 above. The obtained measurement results are shown in FIG.
  • FIGS. 12 to 15 are enlarged schematic diagrams showing the state of the pixel when a voltage is applied to the liquid crystal display device to switch from black display to white display.
  • FIGS. 16 and 17 are a schematic plan view showing an enlarged part of a pixel when the width W1 of the slit 14 is 9 ⁇ m and a schematic plan view showing the alignment state of liquid crystal molecules.
  • FIGS. It is the plane schematic diagram which expanded a part of pixel when width W1 is 5 micrometers, and the plane schematic diagram which shows the orientation state of a liquid crystal molecule.
  • the alignment state of the liquid crystal molecules 50 is almost the same as FIGS. 9 and 11 according to the second embodiment regardless of whether the width W1 of the slit 14 is 9 ⁇ m or 5 ⁇ m.
  • the non-display region 45 is formed in the region to be the display region 40, and the display state is inferior compared to FIGS. 8 and 10 according to the second embodiment.
  • Table 1 also shows that, in Comparative Example 1, when the width W1 of the slit 14 is 7 ⁇ m or less, variations in brightness and roughness of the image occur.
  • Example 3 in the present embodiment, in the liquid crystal display devices according to the first and second embodiments, the influence of the distance between the protrusion 32 and the slit 45 on the light transmittance was examined. Specifically, in the liquid crystal display device 100 according to the first embodiment, the distance between the protrusion 32 and the slit 45 is changed to 3, 5, 8, 10, and 15 ⁇ m, and the width W1 of the slit 14 is set to 5 to 5 for each. The light transmittance was measured in the same manner as in Example 2 by changing the distance in steps of 1 ⁇ m between 9 ⁇ m. The obtained measurement results are shown in FIG.
  • each measurement point in FIG. 20 was plotted corresponding to the area of the transmission region.
  • the obtained measurement results are shown in FIG.
  • the numerical value written in the vicinity of the dot represents the slit width ( ⁇ m)
  • the dots in each graph have slit widths of 9 ⁇ m, 7 ⁇ m, 5 ⁇ m, and 3 ⁇ m in order from the left side in the figure. It is.
  • the widths of the protrusions 32 and the slits 45 are the same, the narrower the distance between the protrusions 32 and the slits 45, the smaller the number of protrusions 32 and slits 45 arranged in the pixel. Since it increases, the area of the transmission region decreases. For this reason, the light transmittance tends to increase as the distance between the protrusion 32 and the slit 45 increases, and the light transmittance tends to decrease as the distance between the protrusion 32 and the slit 45 decreases.
  • the light transmittance is improved by the compensation effect of the circularly polarizing plates 13 and 34 by reducing the width of the slit 45. I can plan.
  • the transmissive liquid crystal display device has been described as an example.
  • the present invention is not limited to this, and can be applied to a transflective liquid crystal display device.
  • the present invention is not limited to this.
  • the shape of the slit may be vertical or horizontal with respect to the pixel surface, and the shape of the protrusion may be vertical or horizontal as well.

Abstract

Disclosed is an MVA mode liquid crystal display device which has high light transmittance and is capable of reducing display failure such as luminance unevenness and textured images. Specifically disclosed is a liquid crystal display device which is provided with a pair of substrates, a liquid crystal layer interposed between the pair of substrates, and an electrode for applying a voltage to the liquid crystal layer. The liquid crystal display device is characterized in that one of the pair of substrates has a plurality of projections for controlling the alignment of liquid crystal molecules in the liquid crystal layer, and the other of the pair of substrates is provided with a plurality of slits in the electrode. The liquid crystal display device is also characterized by additionally comprising circularly polarizing plates which are respectively arranged on a surface of the substrate, said surface being on the opposite side of the substrate to the liquid crystal layer side thereof, and on a surface of the other substrate, said surface being on the opposite side of the other substrate to the liquid crystal layer side thereof.

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、マルチドメイン垂直配向型の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 multi-domain vertical alignment type liquid crystal display device.
液晶表示装置は、薄型で軽量、かつ低消費電力といった特長を活かして様々な分野で用いられている。液晶表示装置は、一対の基板間に液晶層が挟持された構成を有する。液晶表示装置には各種の表示モードがあるが、垂直配向（Ｖｅｒｔｉｃａｌ　Ａｌｉｇｎｍｅｎｔ：ＶＡ）モードは、高いコントラスト比が得られることが知られている。 Liquid crystal display devices are used in various fields by taking advantage of their thin and light weight and low power consumption. A liquid crystal display device has a structure in which a liquid crystal layer is sandwiched between a pair of substrates. There are various display modes in a liquid crystal display device, and it is known that a vertical alignment (Vertical Alignment: VA) mode can provide a high contrast ratio.
ＶＡモードの液晶表示装置の中でも、特許文献１等に記載のマルチドメイン垂直配向型（Ｍｕｌｔｉ－ｄｏｍａｉｎ　Ｖｅｒｔｉｃａｌ　Ａｌｉｇｎｍｅｎｔ：ＭＶＡモード）の液晶表示装置や、特許文献２等に記載の連続的マルチドメイン放射状傾斜配向型（Ｃｏｎｔｉｎｕｏｕｓ　Ｐｉｎｗｈｅｅｌ　Ａｌｉｇｎｍｅｎｔ：ＣＰＡモード）の液晶表示装置は、１画素内における液晶分子の配向方向を複数方向に規制しているため、広い視野角が得られることが知られている。 Among the VA mode liquid crystal display devices, the multi-domain vertical alignment (MVA mode) liquid crystal display device described in Patent Document 1 and the like, and the continuous multi-domain radial tilt described in Patent Document 2 and the like. It is known that an alignment type (Continuous Pinwheel Alignment: CPA mode) liquid crystal display device has a wide viewing angle since the alignment direction of liquid crystal molecules in one pixel is regulated in a plurality of directions.
液晶分子の配向状態を規制するための手法としては、ＭＶＡモードでは、液晶層に電圧を印加するための電極に抜き部（スリット）を設けたり、基板に突起物を形成しており、ＣＰＡモードでは、基板に微小な突起物を放射状に形成している。以下、電極に形成されたスリットを、電極スリットとも称す。 As a method for regulating the alignment state of the liquid crystal molecules, in the MVA mode, the electrode for applying a voltage to the liquid crystal layer is provided with a slit (slit), or a protrusion is formed on the substrate. Then, minute protrusions are radially formed on the substrate. Hereinafter, the slit formed in the electrode is also referred to as an electrode slit.
特開２００３－１４９６４７号公報JP 2003-149647 A 特開２００９－３１９４号公報JP 2009-3194 A
上記ＭＶＡモードの液晶表示装置では、電極スリットや突起のある部分では電圧がかかりにくくなって光の透過率が低下する傾向にあることから、画素内に占める電極スリットや突起は、その面積割合が少ないことが好ましい。例えば、電極スリットであれば、その幅はできるだけ狭いことが好ましい。 In the MVA mode liquid crystal display device, voltage is difficult to be applied to the portion where the electrode slits and protrusions are present, and the light transmittance tends to decrease. Less is preferred. For example, in the case of an electrode slit, the width is preferably as narrow as possible.
しかしながら、電極スリットの幅を狭くすると、電極スリットが設けられた領域にも電界が生じてしまい液晶分子の配向状態が不安定になり、ディスクリネーション（線欠陥）と呼ばれる領域が生じる。この領域では、電極スリット幅を縮小させているにも関わらず光漏れが生じるために光の透過率を向上させることができず、表示画面上に輝度のばらつきが生じることがある。また、この領域は、表示画面上においてザラツキとなって見えることもある。このような傾向は、電極スリット幅を７μｍ以下としたときに顕著である。 However, when the width of the electrode slit is reduced, an electric field is also generated in the region where the electrode slit is provided, the alignment state of the liquid crystal molecules becomes unstable, and a region called disclination (line defect) is generated. In this region, although light leakage occurs despite the reduction of the electrode slit width, the light transmittance cannot be improved, and luminance variation may occur on the display screen. In addition, this region may appear to be rough on the display screen. Such a tendency is remarkable when the electrode slit width is 7 μm or less.
これは、液晶分子の配向状態は、液晶分子の傾斜角度だけでなく液晶分子の傾斜方向にも依存しており、電極スリットに電界が生じることで液晶分子の傾斜方向にばらつきが増えるためと考えられる。なお、液晶分子の傾斜角度とは、液晶層の厚み方向に対する液晶分子の傾き角度であり、傾斜方向とは、液晶分子を基板面へ投影したときの液晶分子の向きである。 This is thought to be because the alignment state of the liquid crystal molecules depends not only on the tilt angle of the liquid crystal molecules but also on the tilt direction of the liquid crystal molecules, and the variation in the tilt direction of the liquid crystal molecules is caused by the generation of an electric field in the electrode slit. It is done. Note that the tilt angle of the liquid crystal molecules is the tilt angle of the liquid crystal molecules with respect to the thickness direction of the liquid crystal layer, and the tilt direction is the direction of the liquid crystal molecules when the liquid crystal molecules are projected onto the substrate surface.
一方、ＣＰＡモードの液晶表示装置は、液晶分子が放射状に配向しているため複屈折による光漏れを起こす方向が多くなり、ＭＶＡモードの液晶表示装置と比べるとコントラスト比が低くなる傾向にある。そのため、例えば、車載用の用途のように、安全性の面から高い視認性が要求される分野においては、より一層のコントラスト比の向上が求められている。 On the other hand, in a CPA mode liquid crystal display device, liquid crystal molecules are aligned radially, so that the direction of light leakage due to birefringence increases, and the contrast ratio tends to be lower than that of an MVA mode liquid crystal display device. Therefore, for example, in a field where high visibility is required from the viewpoint of safety, such as in-vehicle use, further improvement in contrast ratio is required.
本発明は、上記現状に鑑みてなされたものであり、ＭＶＡモードの液晶表示装置において、電極に形成されたスリットの幅を狭くしても、光の透過率が高く、輝度のばらつきや画像のザラツキ等の表示不良を低減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 in an MVA mode liquid crystal display device, even if the width of the slit formed in the electrode is narrowed, the light transmittance is high, the luminance variation and the image An object of the present invention is to provide a liquid crystal display device capable of reducing display defects such as roughness.
本発明者らは、ＭＶＡモードの液晶表示装置について種々検討したところ、電極に形成されたスリットの幅を狭くしたときに液晶分子の配向状態が不安定になる領域が生じ、光の透過率の低下が生じることをまず見いだした。そして、液晶表示装置を構成する一対の基板の液晶層とは反対側の面に設けられている直線偏光板に代えて円偏光板を用いることで、液晶分子の配向方向に依存することなく光源からの光を透過させることができ、これにより上記光の透過率の低下を抑制して、輝度のばらつきや画像のザラツキを低減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 inventors of the present invention have studied various types of MVA mode liquid crystal display devices. As a result, when the width of the slit formed in the electrode is narrowed, a region where the alignment state of the liquid crystal molecules becomes unstable is generated, and the light transmittance is reduced. We first found that a decline occurred. Then, a circularly polarizing plate is used instead of the linearly polarizing plate provided on the surface opposite to the liquid crystal layer of the pair of substrates constituting the liquid crystal display device, so that the light source does not depend on the alignment direction of the liquid crystal molecules. It is possible to transmit the light from the light source, thereby suppressing the decrease in the light transmittance, thereby reducing the variation in brightness and the roughness of the image. The present invention has been achieved.
すなわち、本発明は、一対の基板と、上記一対の基板間に挟持された液晶層と、上記液晶層に電圧を印加するための電極とを備えた液晶表示装置であって、上記一対の基板における一方の基板は、上記液晶層中の液晶分子の配向を制御する複数の突起を有し、上記一対の基板における他方の基板は、上記電極に複数のスリットが形成されており、上記液晶表示装置は、上記一方の基板（第１基板）及び上記他方の基板（第２基板）の液晶層とは反対側の面に円偏光板を更に有する液晶表示装置である。 That is, the present invention is a liquid crystal display device comprising a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and an electrode for applying a voltage to the liquid crystal layer, wherein the pair of substrates One of the substrates has a plurality of protrusions that control the alignment of liquid crystal molecules in the liquid crystal layer, and the other of the pair of substrates has a plurality of slits formed in the electrodes, and the liquid crystal display The apparatus is a liquid crystal display device further having a circularly polarizing plate on a surface opposite to the liquid crystal layer of the one substrate (first substrate) and the other substrate (second substrate).
本発明の液晶表示装置は、ＭＶＡモードの液晶表示装置であって、液晶層に印加する電圧を変化させることにより、液晶層のリタデーションを変化させることで表示を行うものである。 The liquid crystal display device of the present invention is an MVA mode liquid crystal display device, and performs display by changing the retardation of the liquid crystal layer by changing the voltage applied to the liquid crystal layer.
ＭＶＡモードとは、負の誘電率異方性を持つネガ型液晶を用いて、閾値電圧未満（例えば、電圧の無印加状態）のときに、液晶分子を基板面に対して実質的に垂直方向に配向させ、閾値以上の電圧を印加したときに、液晶分子を基板面に対して実質的に水平方向に倒す表示モードである。負の誘電率異方性を有する液晶分子とは、長軸方向よりも短軸方向の誘電率が大きい液晶分子をいう。 The MVA mode is a negative type liquid crystal having negative dielectric anisotropy, and the liquid crystal molecules are substantially perpendicular to the substrate surface when the voltage is less than a threshold voltage (for example, no voltage is applied). This is a display mode in which liquid crystal molecules are tilted substantially horizontally with respect to the substrate surface when a voltage equal to or higher than a threshold is applied. The liquid crystal molecule having negative dielectric anisotropy refers to a liquid crystal molecule having a larger dielectric constant in the minor axis direction than in the major axis direction.
また、ＭＶＡモードでは、液晶分子の配向制御用構造として、電極に形成された複数のスリットと基板面に形成された複数の突起とを有する。電極は、共通電極又は画素電極であり、液晶層への電圧の印加に用いられる。電極に形成されるスリットは、誘電体からなる突起と共に電界を曲げる働きをする。また、基板面に突起が形成されることで、基板の表面形状によって液晶分子は突起に向かって傾斜する。このように、電界を曲げる働きと基板の表面形状による液晶分子の配向制御とによって、各画素において複数のドメインに分割された液晶の配向制御が実現でき、広い視野角の実現や、コントラスト比の向上等が実現できる。 The MVA mode has a plurality of slits formed in the electrode and a plurality of protrusions formed on the substrate surface as the structure for controlling the alignment of liquid crystal molecules. The electrode is a common electrode or a pixel electrode, and is used for applying a voltage to the liquid crystal layer. The slit formed in the electrode functions to bend the electric field together with the protrusion made of a dielectric. Further, by forming the protrusion on the substrate surface, the liquid crystal molecules are inclined toward the protrusion depending on the surface shape of the substrate. In this way, the alignment control of the liquid crystal molecules divided into a plurality of domains in each pixel can be realized by the action of bending the electric field and the alignment control of the liquid crystal molecules according to the surface shape of the substrate. Improvements can be realized.
電極に形成されるスリットの形状は特に限定されるものではないが、例えば、Ｖ字状のスリットによって画素内が４つの領域に分割される形態が挙げられる。また、突起の形状も特に限定されるものではないが、電極に上記Ｖ字状のスリットが形成されている場合には、Ｖ字状に配置される帯状の構造物であると、液晶分子の配向状態を画素内において均一に、かつ、容易に規制できる。 Although the shape of the slit formed in the electrode is not particularly limited, for example, there is a form in which the inside of the pixel is divided into four regions by the V-shaped slit. In addition, the shape of the protrusion is not particularly limited, but when the V-shaped slit is formed in the electrode, the shape of the liquid crystal molecule is determined to be a band-shaped structure arranged in a V-shape. The alignment state can be easily and uniformly regulated in the pixel.
上記円偏光板は、一般に、無偏光から直線偏光を分離する直線偏光子と、直線偏光を円偏光に変換するλ／４位相差板とからなる。λ／４位相差板は、可視光の波長の長さの１／４の厚み方向位相差（９５～１９５ｎｍ）を有する複屈折体であり、好ましくは、１２０～１５０ｎｍの厚み方向位相差を有する複屈折体である。このような円偏光板を上記一対の基板の液晶層とは反対側の面に設けることで、液晶分子の配向方向に依存することなく光源からの光を透過することができ、光の透過率の向上が図れる。 The circularly polarizing plate generally comprises a linear polarizer that separates linearly polarized light from non-polarized light and a λ / 4 retardation plate that converts linearly polarized light into circularly polarized light. The λ / 4 retardation plate is a birefringent body having a thickness direction retardation (95 to 195 nm) that is ¼ of the wavelength of visible light, and preferably has a thickness direction retardation of 120 to 150 nm. It is a birefringent body. By providing such a circularly polarizing plate on the surface opposite to the liquid crystal layer of the pair of substrates, light from the light source can be transmitted without depending on the alignment direction of the liquid crystal molecules, and the light transmittance Can be improved.
本発明の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い。 The configuration of the liquid crystal display device of the present invention is not particularly limited by other components as long as such components are essential.
本発明に係る液晶表示装置においては、光の透過率をより高めるためにスリットの幅を狭くしても、スリット付近で生じる液晶分子の配向不良による光の透過率の低下は、上記した円偏光板によって補償され、結果として光の透過率を高めることができる。 In the liquid crystal display device according to the present invention, even if the slit width is narrowed in order to further increase the light transmittance, the decrease in the light transmittance due to the poor alignment of the liquid crystal molecules occurring in the vicinity of the slit is caused by the circularly polarized light described above. Compensated by the plate, the light transmittance can be increased as a result.
具体的には、上記スリットの幅は、１５μｍ以下であることが好ましい。スリットは、上記のように電圧がかかりにくく光の透過率に劣るため、スリットの幅が１５μｍを超えると光の透過率の低下が大きくなりすぎて、円偏光板によって光の透過率を向上させたとしても、液晶表示装置全体としては光の透過率が低くなってコントラスト比が低下する傾向にある。スリットの幅の下限値は特に限定されるものではないが、本発明においては、上記のようにザラツキ等が生じやすい７μｍ以下としても、スリットの付近で生じる液晶分子の配向不良を円偏光板による補償効果によって補うことができ、更に、スリットの幅を３μｍまで縮小しても、円偏光板による補償効果によって充分な光の透過率を得ることができる。例えば、上記スリットの幅の好ましい下限値は、３μｍである。 Specifically, the width of the slit is preferably 15 μm or less. As described above, the slit is difficult to be applied with voltage and inferior in light transmittance. Therefore, when the slit width exceeds 15 μm, the light transmittance decreases too much, and the circularly polarizing plate improves the light transmittance. Even so, the entire liquid crystal display device tends to have a low light transmittance and a low contrast ratio. Although the lower limit of the width of the slit is not particularly limited, in the present invention, even if the roughness is 7 μm or less, which is likely to cause roughness as described above, poor alignment of the liquid crystal molecules generated in the vicinity of the slit is caused by the circularly polarizing plate. It can be compensated by the compensation effect, and even if the slit width is reduced to 3 μm, sufficient light transmittance can be obtained by the compensation effect of the circularly polarizing plate. For example, a preferable lower limit value of the width of the slit is 3 μm.
突起の幅は特に限定されるものではないが、突起の幅が狭くなると光の透過率が向上する傾向にある。ただし、各画素における光の透過率は、突起の幅のみに影響されるものではなく、突起を形成する材料自体が有する光の透過率にも影響されるものである。 The width of the protrusion is not particularly limited, but when the width of the protrusion is narrowed, the light transmittance tends to be improved. However, the light transmittance in each pixel is not influenced only by the width of the protrusion, but also by the light transmittance of the material itself forming the protrusion.
突起とスリットとの間隔は特に限定されるものではないが、突起及びスリットの幅が同じであれば、突起とスリットとの間隔が狭いもの程、各画素に設けられる本数が増えるため、光の透過率が減少する。本発明においては、このように突起とスリットとの間隔が狭い場合であっても、円偏光板によって光の透過率の低下を補うことができる。 The distance between the protrusion and the slit is not particularly limited, but if the width of the protrusion and the slit is the same, the narrower the distance between the protrusion and the slit, the greater the number of pixels provided in each pixel. Transmittance decreases. In the present invention, even when the distance between the protrusion and the slit is narrow as described above, the reduction in light transmittance can be compensated for by the circularly polarizing plate.
本発明に係る液晶表示装置は、透過型の液晶表示装置又は半透過型の液晶表示装置であってもよい。いずれの液晶表示装置であっても、良好に光の透過率の向上が図れる。 The liquid crystal display device according to the present invention may be a transmissive liquid crystal display device or a transflective liquid crystal display device. In any liquid crystal display device, the light transmittance can be improved satisfactorily.
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。 Each form mentioned above may be combined suitably in the range which does not deviate from the gist of the present invention.
本発明の液晶表示装置によれば、一対の基板の液晶層とは反対側の面に円偏光板を設けることで、電極に形成されたスリットの幅を狭くしても光の透過率を高めることができ、輝度のばらつきや画像のザラツキ等の表示不良が低減された表示特性の良い液晶表示装置を実現できる。 According to the liquid crystal display device of the present invention, by providing the circularly polarizing plate on the surface opposite to the liquid crystal layer of the pair of substrates, the light transmittance is increased even if the width of the slit formed in the electrode is narrowed. In addition, a liquid crystal display device with good display characteristics can be realized in which display defects such as luminance variations and image roughness are reduced.
実施形態１に係る液晶表示装置の構成を示し、画素の断面模式図を示す。The structure of the liquid crystal display device which concerns on Embodiment 1 is shown, and the cross-sectional schematic diagram of a pixel is shown. 実施形態１に係る液晶表示装置の構成を示し、画素の一部を拡大した平面模式図を示す。The structure of the liquid crystal display device which concerns on Embodiment 1 is shown, and the plane schematic diagram which expanded a part of pixel is shown. 実施例１に係る画素の一部を拡大した平面模式図である。3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged. FIG. 実施例１に係る画素の一部を拡大した平面模式図である。3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged. FIG. 実施例１に係る画素の一部を拡大した平面模式図である。3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged. FIG. 実施例１に係る画素の一部を拡大した平面模式図である。3 is a schematic plan view in which a part of a pixel according to Example 1 is enlarged. FIG. 実施例２及び比較例１に係るスリット幅と光の透過率との関係を示すグラフである。It is a graph which shows the relationship between the slit width which concerns on Example 2 and Comparative Example 1, and the transmittance | permeability of light. 実施例２に係る画素の一部を拡大した平面模式図である。FIG. 6 is a schematic plan view in which a part of a pixel according to Example 2 is enlarged. 実施例２に係る液晶分子の配向状態を示す平面模式図である。6 is a schematic plan view illustrating an alignment state of liquid crystal molecules according to Example 2. FIG. 実施例２に係る画素の一部を拡大した平面模式図である。FIG. 6 is a schematic plan view in which a part of a pixel according to Example 2 is enlarged. 実施例２に係る液晶分子の配向状態を示す平面模式図である。6 is a schematic plan view illustrating an alignment state of liquid crystal molecules according to Example 2. FIG. 比較例１に係る画素の一部を拡大した平面模式図である。6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged. FIG. 比較例１に係る画素の一部を拡大した平面模式図である。6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged. FIG. 比較例１に係る画素の一部を拡大した平面模式図である。6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged. FIG. 比較例１に係る画素の一部を拡大した平面模式図である。6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged. FIG. 比較例１に係る画素の一部を拡大した平面模式図である。6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged. FIG. 比較例１に係る液晶分子の配向状態を示す平面模式図である。6 is a schematic plan view showing an alignment state of liquid crystal molecules according to Comparative Example 1. FIG. 比較例１に係る画素の一部を拡大した平面模式図である。6 is a schematic plan view in which a part of a pixel according to Comparative Example 1 is enlarged. FIG. 比較例１に係る液晶分子の配向状態を示す平面模式図である。6 is a schematic plan view showing an alignment state of liquid crystal molecules according to Comparative Example 1. FIG. 実施例３に係る液晶表示装置の光の透過率を示すグラフであって、突起とスリットとの間隔を３、５、８、１０、１５μｍと変化させたときのスリット幅と光の透過率との関係を示したものである。FIG. 10 is a graph showing the light transmittance of the liquid crystal display device according to Example 3, and the slit width and light transmittance when the distance between the protrusion and the slit is changed to 3, 5, 8, 10, and 15 μm; This shows the relationship. 実施例３に係る液晶表示装置の光の透過率を示すグラフであって、図２０における各測定点を、透過領域の面積に対応させてプロットしたものである。FIG. 21 is a graph showing the light transmittance of the liquid crystal display device according to Example 3, in which each measurement point in FIG. 20 is plotted corresponding to the area of the transmission region.
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.
実施形態１
本実施形態では、透過型のＭＶＡモードの液晶表示装置を例に挙げて説明する。図１は、本実施形態に係る液晶表示装置の構成を示し、画素の断面模式図を示す。図２は、本実施形態に係る液晶表示装置の構成を示し、画素の一部を拡大した平面模式図を示す。 Embodiment 1
In the present embodiment, a transmissive MVA mode liquid crystal display device will be described as an example. FIG. 1 shows a configuration of a liquid crystal display device according to this embodiment, and shows a schematic cross-sectional view of a pixel. FIG. 2 shows a configuration of the liquid crystal display device according to the present embodiment, and shows a schematic plan view in which a part of a pixel is enlarged.
図１において、液晶表示装置１００は、アレイ基板１０と、これに対向するように設けられた対向基板３０と、アレイ基板１０と対向基板３０との間に狭持されるように設けられた液晶層２０とを備える。 In FIG. 1, a liquid crystal display device 100 includes an array substrate 10, a counter substrate 30 provided to face the array substrate 10, and a liquid crystal provided to be sandwiched between the array substrate 10 and the counter substrate 30. Layer 20.
アレイ基板１０は、ガラス基板１１の液晶層２０側の主面上に、ここでは図示されていないが、互いに平行に伸びる複数のゲート信号線、ゲート信号線に直交しかつ相互に平行に伸びる複数のソース信号線、ゲート信号線とソース信号線との各交差部に設けられた薄膜トランジスタ（ＴＦＴ）等を有する。 The array substrate 10 is formed on the main surface of the glass substrate 11 on the liquid crystal layer 20 side, although not shown here, a plurality of gate signal lines extending in parallel with each other, and a plurality of gate signal lines extending in parallel with each other. Source signal lines, thin film transistors (TFTs) provided at intersections of gate signal lines and source signal lines.
ゲート信号線及びソース信号線は、ゲート絶縁膜にて覆われており、ゲート絶縁膜上にはドレイン電極が形成されている。これらは層間絶縁膜にて覆われており、層間絶縁膜の上には、画素電極１２が形成されている。画素電極１２とドレイン電極とは、層間絶縁膜に形成されたコンタクトホールを介して接続される。ＴＦＴは、ゲート信号線に接続されたゲート電極と、ソース信号線に接続されたソース電極と、ドレイン電極とを有する。 The gate signal line and the source signal line are covered with a gate insulating film, and a drain electrode is formed on the gate insulating film. These are covered with an interlayer insulating film, and a pixel electrode 12 is formed on the interlayer insulating film. The pixel electrode 12 and the drain electrode are connected through a contact hole formed in the interlayer insulating film. The TFT has a gate electrode connected to the gate signal line, a source electrode connected to the source signal line, and a drain electrode.
画素電極１２は、各画素に対応するように形成されており、液晶分子の配向状態を規制するための複数のスリット１４が形成されている。スリット１４は、基板面を法線方向から見たときに、図２に示すようにＶ字状であり、等間隔に配置されている。 The pixel electrode 12 is formed to correspond to each pixel, and a plurality of slits 14 for regulating the alignment state of liquid crystal molecules is formed. The slits 14 are V-shaped as shown in FIG. 2 when the substrate surface is viewed from the normal direction, and are arranged at equal intervals.
スリット１４が形成された領域は、上記のように光の透過率が低下する傾向にあることから、スリット１４の幅Ｗ１は、できるだけ狭いことが好ましい。具体的には、スリット１４の幅Ｗ１は、１５μｍ以下であることが好ましく、７μｍ以下であることがより好ましく、３μｍ程度まで狭くできることが更に好ましい。 Since the area where the slits 14 are formed tends to decrease the light transmittance as described above, the width W1 of the slits 14 is preferably as narrow as possible. Specifically, the width W1 of the slit 14 is preferably 15 μm or less, more preferably 7 μm or less, and still more preferably narrowed to about 3 μm.
液晶層２０は、ＶＡモードの液晶表示装置に使用されるものであれば特に限定されるものではないが、例えば、負の誘電率異方性を有するネマチック液晶を使用することができる。ＶＡモードは、典型的には、アレイ基板１０及び対向基板３０の液晶層側の面に形成されたポリイミド等からなる垂直配向膜（図示せず）を使用することで実現できる。液晶層２０中の液晶分子は、電圧が印加されていない状態（オフ状態）では、配向膜の表面に対して垂直方向に配向し、しきい値以上の電圧が印加された状態（オン状態）では、水平方向に向かって倒れる。 The liquid crystal layer 20 is not particularly limited as long as it is used in a VA mode liquid crystal display device. For example, a nematic liquid crystal having negative dielectric anisotropy can be used. The VA mode can be typically realized by using a vertical alignment film (not shown) made of polyimide or the like formed on the surface of the array substrate 10 and the counter substrate 30 on the liquid crystal layer side. In a state where no voltage is applied (off state), the liquid crystal molecules in the liquid crystal layer 20 are aligned in a direction perpendicular to the surface of the alignment film, and a state where a voltage higher than the threshold is applied (on state). Then, it falls down in the horizontal direction.
対向基板３０は、ガラス基板３１の液晶層２０側の主面上に複数のリブ状の突起３２を有し、上記画素電極１２と対向して配置された対向電極３３を備える。 The counter substrate 30 includes a plurality of rib-shaped protrusions 32 on the main surface of the glass substrate 31 on the liquid crystal layer 20 side, and includes a counter electrode 33 disposed to face the pixel electrode 12.
複数の突起３２は、液晶分子の配向状態を規制するためのものであり、ここでは、図２に示すように、基板面を法線方向から見たときにＶ字状に配置される帯状の構造物であり、等間隔で配置されている。突起３２の幅Ｗ２は、特に限定されるものではないが、その幅は狭い程、光の透過率を高める傾向にある。ただし、光の透過率の向上効果は、突起３２を形成する材料によって異なる。 The plurality of protrusions 32 are for restricting the alignment state of the liquid crystal molecules. Here, as shown in FIG. 2, when the substrate surface is viewed from the normal direction, the plurality of protrusions 32 are band-shaped. It is a structure and is arranged at equal intervals. The width W2 of the protrusion 32 is not particularly limited. However, the narrower the width, the higher the light transmittance. However, the effect of improving the light transmittance varies depending on the material forming the protrusion 32.
対向基板３０は、例えば、カラーフィルタ基板であり、ここでは、ガラス基板３１の面上にカラーフィルタ層が設けられ、絶縁層を介して対向電極３３が配置されている。対向電極３３は、ＩＴＯ等にて形成される。 The counter substrate 30 is, for example, a color filter substrate. Here, a color filter layer is provided on the surface of the glass substrate 31, and a counter electrode 33 is disposed via an insulating layer. The counter electrode 33 is made of ITO or the like.
スリット１４と突起３２とは、図２に示すように、基板面を法線方向から見たときに、両者は等間隔で、かつ、交互に配置される。このような配置とすることで、各画素内において、液晶分子は、矢印ａ～ｄで示すように４つの方向に配向し、広い視野角において均一な表示を得ることができる。 As shown in FIG. 2, the slits 14 and the protrusions 32 are alternately arranged at equal intervals when the substrate surface is viewed from the normal direction. With such an arrangement, liquid crystal molecules are aligned in four directions as indicated by arrows a to d in each pixel, and uniform display can be obtained over a wide viewing angle.
ここで、本実施形態においては、ガラス基板１１、３１の液晶層２０とは反対側の主面上に、一般的に使用されている直線偏光板ではなく、円偏光板１３、３４が配置される。このように円偏光板１３、３４を設けることで、遮光領域となるスリット１４の幅Ｗ１を狭くしたときに液晶分子の配向不良によって光漏れ等が生じても、液晶分子の配向状態にほとんど影響されることなく光源からの光を透過させることができ、光の透過率を高めることができる。また、光の透過率が高まることで、輝度のばらつきや画像のザラツキを低減でき、表示特性の良い液晶表示装置１００が実現できる。 Here, in the present embodiment, circularly polarizing plates 13 and 34 are arranged on the main surface of the glass substrates 11 and 31 opposite to the liquid crystal layer 20 instead of the generally used linearly polarizing plate. The By providing the circularly polarizing plates 13 and 34 in this way, even if light leakage or the like occurs due to poor alignment of the liquid crystal molecules when the width W1 of the slit 14 serving as a light shielding region is narrowed, the alignment state of the liquid crystal molecules is hardly affected. Therefore, the light from the light source can be transmitted without increasing the light transmittance. In addition, since the light transmittance is increased, variation in luminance and roughness of the image can be reduced, and the liquid crystal display device 100 with good display characteristics can be realized.
上記のように構成された液晶表示装置１００は、例えば、以下のようにして製造される。まず、アレイ基板１０の製造方法について説明する。 The liquid crystal display device 100 configured as described above is manufactured, for example, as follows. First, a method for manufacturing the array substrate 10 will be described.
アレイ基板１０は、洗浄したガラス基板１１の主面上にベースコート膜を形成して、ゲート信号線等の各種配線、ＴＦＴ等を形成し、ゲート絶縁膜で覆った後、ドレイン電極を形成する。そして、基板の主面上を層間絶縁膜で覆い、層間絶縁膜にコンタクトホールを形成する。 In the array substrate 10, a base coat film is formed on the main surface of the cleaned glass substrate 11, various wirings such as gate signal lines, TFTs, and the like are formed, covered with a gate insulating film, and then a drain electrode is formed. Then, the main surface of the substrate is covered with an interlayer insulating film, and a contact hole is formed in the interlayer insulating film.
上記構成を有する基板の主面を覆うようにスパッタリング等の方法により導電膜を形成する。導電膜は、酸化インジウム錫（ＩＴＯ）、酸化インジウム亜鉛（ＩＺＯ）、酸化亜鉛等のように光の透過率の高い導電性材料にて形成する。次いで、得られた導電膜を覆うようにレジスト膜を形成し、露光・現像処理を行って、所望の形状のレジストパターンを形成する。 A conductive film is formed by a method such as sputtering so as to cover the main surface of the substrate having the above structure. The conductive film is formed using a conductive material with high light transmittance such as indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide. Next, a resist film is formed so as to cover the obtained conductive film, and exposure / development processing is performed to form a resist pattern having a desired shape.
得られたレジストパターンを介して導電膜をエッチング処理し、上記したＶ字状のスリット１４を有する画素電極１２を形成する。エッチング処理は、ドライエッチング処理又はウェットエッチング処理のいずれであってもよい。 The conductive film is etched through the obtained resist pattern to form the pixel electrode 12 having the V-shaped slit 14 described above. The etching process may be either a dry etching process or a wet etching process.
一方、対向基板３０は、ガラス基板３１の主面上にカラーフィルタ層（図示せず）を形成し、絶縁層（図示せず）で覆ったのち、感光性樹脂を塗布して露光・現像処理を行うことにより突起３２を形成する。そして、突起３２を覆うようにスパッタ法等によりＩＴＯからなる対向電極３３を形成することにより得られる。 On the other hand, the counter substrate 30 is formed with a color filter layer (not shown) on the main surface of the glass substrate 31 and covered with an insulating layer (not shown). To form the protrusion 32. Then, the counter electrode 33 made of ITO is formed by sputtering or the like so as to cover the protrusion 32.
上記のように作製されたアレイ基板１０と対向基板３０とを、シール材（封止材）を介して貼り合わせ、基板間に液晶を封入する。シール材は、特に限定されるものではなく、紫外線硬化型樹脂や熱硬化型樹脂等を用いることができる。そして、ガラス基板１１、３１の液晶層２０とは反対側の面に円偏光板１３、３４を設けることによって液晶表示装置１００が得られる。
以下に、本実施形態を実施例及び比較例に基づきより詳細に説明する。 The array substrate 10 and the counter substrate 30 manufactured as described above are bonded together via a sealing material (sealing material), and liquid crystal is sealed between the substrates. The sealing material is not particularly limited, and an ultraviolet curable resin, a thermosetting resin, or the like can be used. And the liquid crystal display device 100 is obtained by providing the circularly-polarizing plates 13 and 34 in the surface on the opposite side to the liquid crystal layer 20 of the glass substrates 11 and 31. FIG.
Below, this embodiment is described in detail based on an Example and a comparative example.
実施例１
スリット１４の幅Ｗ１が５μｍ、突起３２の幅Ｗ２が１１μｍ、突起３２とスリット１４との間隔が１５μｍである液晶表示装置１００を用いて、画素の表示状態を観察した。突起３２は、樹脂にて形成されており、光の透過率はおよそ４０％である。図３～６は、液晶表示装置１００に電圧を印加して黒表示から白表示へ切り換えたときの画素の状態を示す拡大模式図である。 Example 1
The display state of the pixels was observed using the liquid crystal display device 100 in which the width W1 of the slit 14 was 5 μm, the width W2 of the protrusion 32 was 11 μm, and the distance between the protrusion 32 and the slit 14 was 15 μm. The protrusion 32 is made of resin and has a light transmittance of about 40%. 3 to 6 are enlarged schematic diagrams showing the state of the pixel when a voltage is applied to the liquid crystal display device 100 to switch from black display to white display.
図３～６において、画素内には、表示領域４０と非表示領域４５とを有する。スリット１４及び突起３２が配置された領域は、光の透過率が低いため、非表示領域４５となっている。また、Ｔ１→Ｔ２→Ｔ３→Ｔ４の順に時間が経過しており、Ｔ１→Ｔ２→Ｔ３→Ｔ４の間は約１秒である。 3 to 6, each pixel has a display area 40 and a non-display area 45. The area where the slits 14 and the protrusions 32 are arranged is a non-display area 45 because the light transmittance is low. Further, T 1 → T 2 → and over time in the order of T 3 → T 4, between T 1 → T 2 → T 3 → T 4 is about 1 second.
上記のようにスリット１４の幅Ｗ１は、５μｍと狭くなっているが、スリット１４の周辺には光漏れ等は生じておらず、輝度のばらつき等は見られなかった。また、図３～６に示す画素の状態はほぼ同じであり、時間が経過してもほとんど変化は見られず、画像のザラツキも見られなかった。 As described above, the width W1 of the slit 14 is as narrow as 5 μm. However, no light leakage or the like occurred around the slit 14, and no variation in luminance was observed. Also, the states of the pixels shown in FIGS. 3 to 6 were almost the same, and almost no change was seen over time, and no roughness of the image was seen.
これは、本実施例においては、ガラス基板１１、３１の液晶層２０とは反対側の主面上に円偏光板１３、３４が設けられており、円偏光板１３、３４によって光の透過率の低下が補償されているためと考えられる。 In this embodiment, the circularly polarizing plates 13 and 34 are provided on the main surface of the glass substrates 11 and 31 opposite to the liquid crystal layer 20, and the light transmittance is transmitted by the circularly polarizing plates 13 and 34. This is thought to be due to the compensation of the decrease in.
実施例２
本実施例では、実施形態１に係る液晶表示装置１００において、スリット１４の幅Ｗ１を５～９μｍの間で１μｍ刻みに変化させて、光の透過率を各々測定した。測定は、分光光度計（ＴＯＰＣＯＮ社製、型番ＢＭ－５）を用いて、１画素あたりの光の透過率を求めた。得られた測定結果を図７に示す。 Example 2
In this example, in the liquid crystal display device 100 according to the first embodiment, the light transmittance was measured by changing the width W1 of the slit 14 in increments of 1 μm between 5 and 9 μm. For the measurement, the transmittance of light per pixel was obtained using a spectrophotometer (manufactured by TOPCON, model number BM-5). The obtained measurement results are shown in FIG.
また、各スリット１４の幅Ｗ１における液晶表示装置１００の表示特性について、以下のように評価した。
○：輝度のばらつきや画像のザラツキが生じなかった。
△：輝度のばらつきや画像のザラツキが少し生じた。
×：輝度のばらつきや画像のザラツキが生じた。
得られた評価結果を表１に示す。 Further, the display characteristics of the liquid crystal display device 100 in the width W1 of each slit 14 were evaluated as follows.
○: Brightness variation and image roughness did not occur.
(Triangle | delta): The dispersion | variation in a brightness | luminance and the slight roughness of an image produced.
X: Variation in luminance and roughness of the image occurred.
The obtained evaluation results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
図７及び表１に示すように、実施例２に係る液晶表示装置では、スリット１４の幅Ｗ１が７μｍ以下となっても良好な表示特性が得られ、スリット１４の幅Ｗ１が５μｍと狭くても画像のザラツキ等がなく良好な表示特性が得られた。これは、液晶分子の配向状態を規制するスリット１４の幅Ｗ１が狭くなることで液晶分子の配向不良は生じているものの、円偏光板１３、３４による補償効果によって高い光の透過率が得られ、これにより光学特性上の不具合を起こすことなく光の透過率の向上が図れているものと考えられる。 As shown in FIG. 7 and Table 1, in the liquid crystal display device according to Example 2, good display characteristics were obtained even when the width W1 of the slit 14 was 7 μm or less, and the width W1 of the slit 14 was as narrow as 5 μm. In addition, there was no roughness of the image and good display characteristics were obtained. This is because although the width W1 of the slit 14 that regulates the alignment state of the liquid crystal molecules is reduced, the liquid crystal molecules are poorly aligned, but a high light transmittance is obtained by the compensation effect of the circularly polarizing plates 13 and 34. Thus, it is considered that the light transmittance can be improved without causing problems in optical characteristics.
スリット１４の幅Ｗ１が９μｍと５μｍであるときの表示状態及び液晶分子の配向状態を図８～１１を用いて説明する。なお、突起３２の幅は１１μｍであり、突起３２とスリットとの間隔は１５μｍである。図８、９は、スリット１４の幅Ｗ１が９μｍであるときの画素の一部を拡大した平面模式図及び液晶分子の配向状態を示す平面模式図であり、図１０、１１は、スリット１４の幅Ｗ１が５μｍであるときの画素の一部を拡大した平面模式図及び液晶分子の配向状態を示す平面模式図である。図９、１１において白抜きの液晶分子５０は、良好な配向状態であることを示し、着色された液晶分子５０ａは、配向不良が生じていることを示す。 The display state and the alignment state of the liquid crystal molecules when the width W1 of the slit 14 is 9 μm and 5 μm will be described with reference to FIGS. In addition, the width | variety of the processus | protrusion 32 is 11 micrometers and the space | interval of the processus | protrusion 32 and a slit is 15 micrometers. FIGS. 8 and 9 are a schematic plan view showing an enlarged part of a pixel when the width W1 of the slit 14 is 9 μm and a schematic plan view showing the alignment state of liquid crystal molecules. FIGS. It is the plane schematic diagram which expanded a part of pixel when width W1 is 5 micrometers, and the plane schematic diagram which shows the orientation state of a liquid crystal molecule. 9 and 11, white liquid crystal molecules 50 indicate a good alignment state, and colored liquid crystal molecules 50 a indicate that alignment failure occurs.
図８、９に示すように、スリット１４の幅Ｗ１が９μｍと広い場合には、液晶分子５０は良好な配向状態となり、光漏れ等のない良好な表示特性を有するものとなった。 As shown in FIGS. 8 and 9, when the width W1 of the slit 14 is as wide as 9 μm, the liquid crystal molecules 50 are in a good alignment state and have good display characteristics without light leakage.
また、図１０、１１に示すように、スリット１４の幅Ｗ１が５μｍと狭い場合には、スリット１４の周囲で液晶分子５０ａに配向不良が生じており、スリット１４に若干の光漏れが生じている。しかしながら、円偏光板１３、３４によって液晶分子５０ａの配向不良による光の透過率の低減は補償され、これにより、図７に示すように高い光の透過率が得られ、また、画素全体に占める表示領域４０の割合が高いものとなった。 Further, as shown in FIGS. 10 and 11, when the width W1 of the slit 14 is as narrow as 5 μm, the liquid crystal molecules 50a are poorly aligned around the slit 14, and some light leakage occurs in the slit 14. Yes. However, the circularly polarizing plates 13 and 34 compensate for the reduction in light transmittance due to the poor alignment of the liquid crystal molecules 50a, thereby obtaining a high light transmittance as shown in FIG. 7 and occupying the entire pixel. The ratio of the display area 40 became high.
比較例１
本比較例に係る液晶表示装置は、図１、２に示す液晶表示装置１００において、円偏光板１３、３４を直線偏光板に変更した。直線偏光板としては、ポリビニルアルコール（ＰＶＡ）フィルムに２色性を有するヨウ素錯体等の異方性材料を吸着配向させたものを用いた。そして、それ以外は上記実施例２と同様にして光の透過率及び表示特性を測定した。得られた測定結果を図７及び表１に示す。 Comparative Example 1
In the liquid crystal display device according to this comparative example, the circularly polarizing plates 13 and 34 in the liquid crystal display device 100 shown in FIGS. As the linear polarizing plate, a polyvinyl alcohol (PVA) film obtained by adsorbing and orienting an anisotropic material such as an iodine complex having dichroism was used. Other than that, the light transmittance and display characteristics were measured in the same manner as in Example 2 above. The obtained measurement results are shown in FIG.
図７及び表１から明らかなように、本比較例では、スリット１４の幅Ｗ１が７μｍ以下となると、光の透過率に大きな低下が見られた。また、スリット１４の幅Ｗ１が５μｍであるときには、実施例２の光の透過率が約４．３％であるのに対し、比較例１では光の透過率が約３．５５％となった。 As is apparent from FIG. 7 and Table 1, in this comparative example, when the width W1 of the slit 14 was 7 μm or less, a large decrease in light transmittance was observed. Further, when the width W1 of the slit 14 is 5 μm, the light transmittance of Example 2 is about 4.3%, whereas the light transmittance of Comparative Example 1 is about 3.55%. .
また、上記実施例１と同様に、スリット４５の幅Ｗ１が５μｍ、突起３２の幅Ｗ２が１１μｍであるであるものについて画素の変化を観察した。得られた観察結果を図１２～１５に示す。図１２～１５は、液晶表示装置に電圧を印加して黒表示から白表示へ切り換えたときの画素の状態を示す拡大模式図である。図１２～１５において、Ｔ１→Ｔ２→Ｔ３→Ｔ４の順に時間が経過しており、Ｔ１→Ｔ２→Ｔ３→Ｔ４の間は約１秒である。 Similarly to Example 1, the change in pixels was observed for a slit 45 having a width W1 of 5 μm and a protrusion 32 having a width W2 of 11 μm. The obtained observation results are shown in FIGS. 12 to 15 are enlarged schematic diagrams showing the state of the pixel when a voltage is applied to the liquid crystal display device to switch from black display to white display. In Figure 12 ~ 15, T 1 → T 2 → and over time in the order of T 3 → T 4, between T 1 → T 2 → T 3 → T 4 is about 1 second.
図１２～１５において波線及び矢印で示すように、本来は表示領域４０となる部分に不規則な形状の非表示領域４５が形成されており、この非表示領域４５は時間の経過とともに変形している。これにより、得られた画像はザラツキがあるように見える。なお、スリットの幅Ｗ１が５μｍであるときに、実施例２と比較例１との光の透過率の差は約０．７５％ではあるが、輝度のばらつきや画像ザラツキは図１２～１５に示すように大きいものである。 12 to 15, an irregularly shaped non-display area 45 is originally formed in a portion that becomes the display area 40, and the non-display area 45 is deformed over time. Yes. As a result, the obtained image appears to be rough. When the slit width W1 is 5 μm, the difference in light transmittance between Example 2 and Comparative Example 1 is about 0.75%, but variations in luminance and image roughness are shown in FIGS. As shown, it is big.
更に、図８～１１と同様に、スリット１４の幅Ｗ１が９μｍと５μｍであるものについて、表示状態及び液晶分子の配向状態を調べた。図１６、１７は、スリット１４の幅Ｗ１が９μｍであるときの画素の一部を拡大した平面模式図及び液晶分子の配向状態を示す平面模式図であり、図１８、１９は、スリット１４の幅Ｗ１が５μｍであるときの画素の一部を拡大した平面模式図及び液晶分子の配向状態を示す平面模式図である。 Further, as in FIGS. 8 to 11, the display state and the alignment state of the liquid crystal molecules were examined for the slits having the width W1 of 9 μm and 5 μm. FIGS. 16 and 17 are a schematic plan view showing an enlarged part of a pixel when the width W1 of the slit 14 is 9 μm and a schematic plan view showing the alignment state of liquid crystal molecules. FIGS. It is the plane schematic diagram which expanded a part of pixel when width W1 is 5 micrometers, and the plane schematic diagram which shows the orientation state of a liquid crystal molecule.
図１７、１９に示すように、スリット１４の幅Ｗ１が９μｍである場合も５μｍである場合も液晶分子５０の配向状態は、実施例２に係る図９、１１とほぼ同じである。しかしながら、図１６、１８に示す表示状態は、表示領域４０となるべき領域に非表示領域４５が形成されており、実施例２に係る図８、１０と比べて表示状態が劣る。また、表１にも、比較例１においては、スリット１４の幅Ｗ１が７μｍ以下である場合に輝度のばらつきや画像のザラツキが生じていることが示されている。なお、スリット１４の幅Ｗ１が９μｍである場合には、図１６に示すようにスリット１４や突起３２によって暗線が見えているが、この暗線領域は小さく、また、時間経過による動きが少ないため、表１に示したようにザラツキは見えていない。 As shown in FIGS. 17 and 19, the alignment state of the liquid crystal molecules 50 is almost the same as FIGS. 9 and 11 according to the second embodiment regardless of whether the width W1 of the slit 14 is 9 μm or 5 μm. However, in the display state shown in FIGS. 16 and 18, the non-display region 45 is formed in the region to be the display region 40, and the display state is inferior compared to FIGS. 8 and 10 according to the second embodiment. Table 1 also shows that, in Comparative Example 1, when the width W1 of the slit 14 is 7 μm or less, variations in brightness and roughness of the image occur. When the width W1 of the slit 14 is 9 μm, dark lines are visible by the slits 14 and the protrusions 32 as shown in FIG. 16, but the dark line area is small and the movement due to the passage of time is small. As shown in Table 1, the roughness is not visible.
このように本比較例においては、円偏光板が用いられていないため、上記実施例１、２に比べて表示特性に劣るものとなった。 Thus, in this comparative example, since the circularly-polarizing plate was not used, it became inferior to the display characteristic compared with the said Examples 1 and 2.
実施例３
本実施例では、上記実施例１、２に係る液晶表示装置において、突起３２とスリット４５との間隔が光の透過率に与える影響について調べた。具体的には、実施形態１に係る液晶表示装置１００において、突起３２とスリット４５との間隔を３、５、８、１０、１５μｍと変化させるとともに、各々について、スリット１４の幅Ｗ１を５～９μｍの間で１μｍ刻みに変化させて、実施例２と同様にして光の透過率を測定した。得られた測定結果を図２０に示す。 Example 3
In the present embodiment, in the liquid crystal display devices according to the first and second embodiments, the influence of the distance between the protrusion 32 and the slit 45 on the light transmittance was examined. Specifically, in the liquid crystal display device 100 according to the first embodiment, the distance between the protrusion 32 and the slit 45 is changed to 3, 5, 8, 10, and 15 μm, and the width W1 of the slit 14 is set to 5 to 5 for each. The light transmittance was measured in the same manner as in Example 2 by changing the distance in steps of 1 μm between 9 μm. The obtained measurement results are shown in FIG.
また、図２０における各測定点を、透過領域の面積に対応させてプロットした。得られた測定結果を図２１に示す。なお、図２１において、ドットの近傍に記載された数値はスリットの幅（μｍ）を表しており、各グラフのドットは、図中の左側から順にスリット幅が９μｍ、７μｍ、５μｍ、３μｍのものである。 Moreover, each measurement point in FIG. 20 was plotted corresponding to the area of the transmission region. The obtained measurement results are shown in FIG. In FIG. 21, the numerical value written in the vicinity of the dot represents the slit width (μm), and the dots in each graph have slit widths of 9 μm, 7 μm, 5 μm, and 3 μm in order from the left side in the figure. It is.
図２０、２１に示すように、突起３２及びスリット４５の幅が同じものであれば、突起３２とスリット４５との間隔が狭いもの程、画素内に配置される突起３２及びスリット４５の数が増えるため透過領域の面積は減少する。そのため、突起３２とスリット４５との間隔が広いもの程、光の透過率は高くなる傾向にあり、突起３２とスリット４５との間隔が狭いもの程、光の透過率は減少する傾向にある。しかしながら、本実施例においては、突起３２とスリット４５との間隔を３μｍまで狭くしても、スリット４５の幅を狭くすることで円偏光板１３、３４の補償効果によって光の透過率の向上が図れる。 As shown in FIGS. 20 and 21, if the widths of the protrusions 32 and the slits 45 are the same, the narrower the distance between the protrusions 32 and the slits 45, the smaller the number of protrusions 32 and slits 45 arranged in the pixel. Since it increases, the area of the transmission region decreases. For this reason, the light transmittance tends to increase as the distance between the protrusion 32 and the slit 45 increases, and the light transmittance tends to decrease as the distance between the protrusion 32 and the slit 45 decreases. However, in this embodiment, even if the distance between the protrusion 32 and the slit 45 is reduced to 3 μm, the light transmittance is improved by the compensation effect of the circularly polarizing plates 13 and 34 by reducing the width of the slit 45. I can plan.
なお、上記実施形態では、透過型の液晶表示装置を例に挙げて説明したが、本発明はこれに限定されるものではなく、半透過型の液晶表示装置にも適用できる。 In the above embodiment, the transmissive liquid crystal display device has been described as an example. However, the present invention is not limited to this, and can be applied to a transflective liquid crystal display device.
また、上記実施形態では、画素電極にＶ字状のスリットが形成され、帯状の突起がＶ字状に配置された例を挙げて説明したが、本発明はこれに限定されるものではなく、スリットの形状は、画素面に対して縦方向でも横方向であってもよく、また、突起の形状も同様に縦方向でも横方向であってもよい。 Further, in the above-described embodiment, the example in which the V-shaped slit is formed in the pixel electrode and the band-shaped protrusion is arranged in the V-shape has been described, but the present invention is not limited to this. The shape of the slit may be vertical or horizontal with respect to the pixel surface, and the shape of the protrusion may be vertical or horizontal as well.
更に、上記説明では、画素電極１２にスリット１４を形成した例を挙げて説明したが、本発明においては、対向電極３３にスリットを形成することも可能であり、このような構成によっても上記と同様の効果が得られる。 Furthermore, in the above description, the example in which the slit 14 is formed in the pixel electrode 12 has been described. However, in the present invention, it is also possible to form a slit in the counter electrode 33. Similar effects can be obtained.
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、２００９年５月２７日に出願された日本国特許出願２００９－１２７９３４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. 2009-127934 filed on May 27, 2009. The contents of the application are hereby incorporated by reference in their entirety.
１０　アレイ基板
１１、３１　ガラス基板
１２　画素電極
１３、３４　円偏光板
１４　スリット
２０　液晶層
３０　対向基板
３２　突起
３３　対向電極
４０　表示領域
４５　非表示領域
５０、５０ａ　液晶分子
１００　液晶表示装置
Ｗ１　スリットの幅
Ｗ２　突起の幅 10 array substrate 11, 31 glass substrate 12 pixel electrode 13, 34 circularly polarizing plate 14 slit 20 liquid crystal layer 30 counter substrate 32 protrusion 33 counter electrode 40 display region 45 non-display region 50, 50a liquid crystal molecule 100 liquid crystal display device W1 slit width W2 Width of protrusion

Claims (3)

  1. 一対の基板と、該一対の基板間に挟持された液晶層と、該液晶層に電圧を印加するための電極とを備えた液晶表示装置であって、
    該一対の基板における一方の基板は、該液晶層中の液晶分子の配向を制御する複数の突起を有し、
    該一対の基板における他方の基板は、該電極に複数のスリットが形成されており、
    該液晶表示装置は、該一方の基板及び該他方の基板の液晶層とは反対側の面に円偏光板を更に有することを特徴とする液晶表示装置。     A liquid crystal display device comprising a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and an electrode for applying a voltage to the liquid crystal layer,
    One substrate of the pair of substrates has a plurality of protrusions that control the alignment of liquid crystal molecules in the liquid crystal layer,
    The other substrate of the pair of substrates has a plurality of slits formed in the electrode,
    The liquid crystal display device further includes a circularly polarizing plate on a surface opposite to the liquid crystal layer of the one substrate and the other substrate.
  2. 前記スリットの幅は、１５μｍ以下であることを特徴とする請求項１記載の液晶表示装置。 2. The liquid crystal display device according to claim 1, wherein the slit has a width of 15 [mu] m or less.
  3. 前記液晶表示装置は、透過型の液晶表示装置又は半透過型の液晶表示装置であることを特徴とする請求項１又は２記載の液晶表示装置。 3. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a transmissive liquid crystal display device or a transflective liquid crystal display device.
PCT/JP2010/056215 2009-05-27 2010-04-06 Liquid crystal display device WO2010137407A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003186017A (en) * 2001-10-12 2003-07-03 Fujitsu Display Technologies Corp Liquid crystal display device
JP2006091229A (en) * 2004-09-22 2006-04-06 Sharp Corp Liquid crystal display
JP2006154585A (en) * 2004-11-30 2006-06-15 Sanyo Electric Co Ltd Liquid crystal display device
JP2006330605A (en) * 2005-05-30 2006-12-07 Sharp Corp Liquid crystal display device
JP2007114675A (en) * 2005-10-24 2007-05-10 Toshiba Matsushita Display Technology Co Ltd Liquid crystal display device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003186017A (en) * 2001-10-12 2003-07-03 Fujitsu Display Technologies Corp Liquid crystal display device
JP2006091229A (en) * 2004-09-22 2006-04-06 Sharp Corp Liquid crystal display
JP2006154585A (en) * 2004-11-30 2006-06-15 Sanyo Electric Co Ltd Liquid crystal display device
JP2006330605A (en) * 2005-05-30 2006-12-07 Sharp Corp Liquid crystal display device
JP2007114675A (en) * 2005-10-24 2007-05-10 Toshiba Matsushita Display Technology Co Ltd Liquid crystal display device

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