WO2001073507A1 - Dispositif d'affichage a cristaux liquides - Google Patents

Dispositif d'affichage a cristaux liquides Download PDF

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Publication number
WO2001073507A1
WO2001073507A1 PCT/JP2000/001861 JP0001861W WO0173507A1 WO 2001073507 A1 WO2001073507 A1 WO 2001073507A1 JP 0001861 W JP0001861 W JP 0001861W WO 0173507 A1 WO0173507 A1 WO 0173507A1
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WO
WIPO (PCT)
Prior art keywords
liquid crystal
pixel electrode
substrate
electrodes
electrode
Prior art date
Application number
PCT/JP2000/001861
Other languages
English (en)
Japanese (ja)
Inventor
Kouji Hayakawa
Haruhisa Okumura
Ikuko Mori
Original Assignee
Hitachi, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi, Ltd. filed Critical Hitachi, Ltd.
Priority to PCT/JP2000/001861 priority Critical patent/WO2001073507A1/fr
Publication of WO2001073507A1 publication Critical patent/WO2001073507A1/fr

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Classifications

    • 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
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/12—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode
    • G02F2201/121—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode common or background
    • 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
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/12—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode
    • G02F2201/128—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode field shaping

Definitions

  • the present invention relates to a liquid crystal display device in which a plurality of pixel electrodes are two-dimensionally arranged, and more particularly, to an active matrix liquid crystal display device in which signal voltages having different polarities are applied between adjacent pixel electrodes.
  • Japanese Patent Laid-Open Publication No. Hei 6-281959 discloses that a switching element such as a thin film transistor (TFT) is provided for each pixel electrode in order to select a plurality of pixel electrodes.
  • TFT thin film transistor
  • An active matrix type liquid crystal display device is described.
  • FIG. 13 is a cross-sectional view of a matrix-type liquid crystal display device described in FIG. 2 (B) of Prior Art 1 described above.
  • the pixel electrodes 18 (a) and 18 (b) apply a high positive voltage or a low negative voltage to the pixel electrodes 18 (a) and 18 (b) with respect to the potential (reference potential) of the common electrode 31.
  • a display voltage By applying a display voltage, a vertical electric field 43 is generated, the alignment of the liquid crystal molecules 23 is controlled, and the image is displayed by controlling the light transmittance.
  • Japanese Patent Laid-Open Publication No. Hei 6-1188447 discloses a display voltage applied to a pixel electrode at a constant period such as one field in order to prevent deterioration of liquid crystal molecules.
  • a liquid crystal display device in which the polarity is inverted is described.
  • the prior art 2 also describes a line inversion driving method in which the polarity of the display voltage of the pixel electrode is inverted every horizontal scanning period (each row).
  • FIG. 14 is a plan view of a plurality of pixel electrodes for explaining the line inversion driving method.
  • the plurality of pixel electrodes 18 are arranged in a matrix along the X axis and the y axis.
  • the + symbol indicates that a display voltage of positive polarity is applied to the pixel electrode 18 with respect to the reference potential applied to the common electrode 31, and the symbol indicates that a display voltage of negative polarity is applied to the pixel electrode 18.
  • the polarities of the pixel electrodes 18 (a) and 18 (b) in adjacent rows are different, and the pixel electrodes in the same row (pixel electrodes in a line parallel to the X axis) have the same polarity.
  • a display voltage is applied.
  • the lateral electric field 42 between adjacent pixel electrodes with different polarities causes reverse tilt where the tilt angle 24 of the liquid crystal molecules 23 is different from the normal range. Domain 32 occurs.
  • an alignment film 21 is formed on the pixel electrode substrate 27, and an alignment process such as a rubbing process of rubbing with a cloth or the like is performed.
  • the liquid crystal molecules 23 are oriented at a specific angle (tilt angle 24) with respect to the main surface of the pixel electrode substrate 27 in the rubbing direction (the direction rubbed with a cloth or the like) without applying an electric field. To orient.
  • the reverse tilt domain since the force of the transverse electric field 42 is strong, the liquid crystal molecules having the property of an electric dipole are applied to the pixel electrode substrate 27 at a different angle (reverse tilt 25) from the other regions. In contrast, they will be oriented. Accordingly, the reverse tilt domain has a different optical property from other regions, and causes deterioration of image quality such as afterimages and uneven lighting.
  • the reverse tilt domain can be made inconspicuous by hiding it with a light-shielding film formed on the common electrode substrate 28 or the pixel electrode substrate 27.However, the aperture ratio of the pixel is reduced, and the brightness of the display device is reduced. This was the cause of the decline.
  • the object of the present invention is to reduce the reverse tilt domain, It is to eliminate image defects such as unevenness.
  • the above object is to form a non-electrode portion such as a slit-shaped opening in a common electrode corresponding to an adjacent pixel electrode in which a horizontal electric field becomes strong, and to center the non-electrode portion from the center between adjacent pixel electrodes. Can be achieved by shifting the reverse tilt domain to the side where the reverse tilt domain occurs.
  • FIG. 1 and 2 are a cross-sectional view and a plan view, respectively, of a liquid crystal display device for explaining the principle of the present invention. Since the same reference numerals are used as those in FIG. 13 described above, detailed description of the reference numerals is omitted.
  • FIG. 1 is a sectional view taken along the line AA of FIG.
  • a region where no electrode exists in the common electrode 31 (common electrode absence portion 33) is provided corresponding to the inter-electrode region of the adjacent pixel electrodes 18 (a) and 18 (b). ing.
  • the center 35 of the common electrode absence part 33 is provided so as to be shifted from the center 34 between the pixel electrodes on the side where the reverse tilt domain 32 is generated.
  • FIG. 3 is a cross-sectional view of the liquid crystal display device showing the state of the electric field of the liquid crystal display device employing the present invention.
  • the region where the equipotential lines 40 are inclined is narrower at the end of the pixel electrode 18 (b) on the side where the center 35 of the common electrode absence portion 33 is shifted.
  • the shape of the line of electric force 4 1 the inclination of the line of electric force at the end of the pixel electrode 18 (b) on the side shifted from the center 35 of the common electrode absence part 3 3 3 It can be understood that the component of the lateral electric field 42 is weakened.
  • the lateral electric field component 42 at the end of the pixel electrode 18 (b) where the reverse tilt domain 32 is generated can be weakened, the range in which the reverse tilt domain occurs can be reduced. Can be.
  • the lateral electric field component 42 at the end of the pixel electrode 18 (a) away from the center 35 of the common electrode absent part 33 becomes stronger, but the end of the pixel electrode 18 (a) has no reverse tilt domain. , There is no problem.
  • the reason why the reverse tilt domain does not occur at the end of the pixel electrode 18 (a) shown in FIG. 3 is that at the end on the pixel electrode 18 (a) side, the horizontal electric field 42 causes the liquid crystal molecules 23 to move to the original tilt angle 24 direction. This is because it functions to orient the crystal.
  • FIG. 4 is a graph comparing the light blocking ability in the vicinity of a region between pixel electrodes between a liquid crystal display device to which the present invention is applied and a conventional liquid crystal display device having no common electrode absent portion.
  • the horizontal axis is the position with the center 34 between the pixel electrodes as the zero point.
  • the unit is zm, and the vertical axis is the light transmittance.
  • 45 is the transmittance curve of the present invention
  • 46 is the transmittance curve of the conventional liquid crystal display device.
  • the light-exiting region 32b of the liquid crystal display device of the present invention is closer to the center 34 between the pixel electrodes than the conventional light-exiting region 32a.
  • the region through which the light passes corresponds to the reverse tilt domain.
  • a region where light transmission cannot be controlled by the pixel electrode can be confined in a narrow region near the center 34 between the pixel electrodes, and as shown in FIG. 1 and FIG.
  • the area shielded by the first light shield 2 or the second light shield 29 can be reduced, and the aperture ratio of the pixel portion can be improved.
  • the data shown in Fig. 4 shows that the pixel electrode interval is 1.8 zm, the width of the slit in the common electrode absence part 33 is 3.0 // m, and the slit in the common electrode absence part 33 is Center 35 1.35 yamTFT substrate
  • the figure shows a case where they are arranged shifted in the rubbing direction.
  • the reverse tilt domain can be brought closer to the center 34 between the pixel electrodes by about 1 m than the conventional one.
  • the opening can be made as wide as about 1 m, a reverse tilt domain does not occur in the lighting region, and the electrode absence portion 33 is not in the lighting region, so that a uniform image display can be obtained.
  • FIGS. 6 (A) to 6 (E) are plan views of a pixel portion of a liquid crystal display device for explaining a direction in which a reverse tilt domain occurs.
  • FIGS. 6 (A) to 6 (E) show the alignment film 21 of the pixel electrode substrate 27 when different polarities are applied between the pixel electrodes 18 (a) and 18 (b).
  • the relationship between the rubbing direction 26 and the rubbing direction 36 of the alignment film 22 of the common electrode substrate 28 indicates the direction in which the reverse tilt domain emerges.
  • . 6A to 6E show plan views when viewed from above the common electrode substrate 28.
  • the pixel electrode substrate 27 rubs rightward (in the direction of the arrow 26) along the center line 34 between the pixel electrodes, and the common electrode substrate 28 is the pixel electrode substrate.
  • 9 shows a case where rubbing is performed 90 degrees counterclockwise with respect to the rubbing direction 26 of the pixel electrode substrate, and the right side of the rubbing direction 26 of the pixel electrode substrate with respect to the center line 34 between the pixel electrodes.
  • a reverse tilt domain is generated at the end of the pixel electrode 18 (b).
  • the pixel electrode substrate 27 is rubbed 45 degrees clockwise (in the direction of the arrow 26) with respect to the center line 34 between the pixel electrodes, and the common electrode substrate 27 is rubbed. Indicates the case where the rubbing is performed 90 degrees counterclockwise 36 with respect to the rubbing direction 26 of the pixel electrode substrate.
  • a reverse tilt domain is generated at the end of the pixel electrode 18 (b) in the rubbing direction 26 of the pixel electrode substrate with respect to the line 34.
  • the pixel electrode substrate 27 is rubbed 90 degrees clockwise (in the direction of arrow 26) with respect to the center line 34 between the pixel electrodes, and the common electrode substrate 28 is rubbed. Shows the case where the rubbing is performed 90 degrees counterclockwise 36 with respect to the rubbing direction 26 of the pixel electrode substrate, and the rubbing direction 26 of the pixel electrode substrate with respect to the center line 34 between the pixel electrodes.
  • a reverse tilt domain is generated at the end of the pixel electrode 18 (b).
  • the pixel electrode substrate 27 rubs clockwise (in the direction of arrow 26) by 135 degrees with respect to the center line 34 between the pixel electrodes, and the common electrode substrate 28 Shows the case where rubbing is performed 90 degrees counterclockwise with respect to the rubbing direction 26 of the pixel electrode substrate 36, and the rubbing direction of the pixel electrode substrate with respect to the center line 34 between the pixel electrodes.
  • Reverse tilt domains are generated at the ends of the 26 pixel electrodes 18 (b).
  • the pixel electrode substrate 27 is 180 degrees clockwise (in the direction of arrow 26) with respect to the rubbing direction of the pixel electrode substrate in the example shown in FIG. 6 (A).
  • the rubbing is performed in the direction of 90 ° counterclockwise with respect to the rubbing direction 26 of the pixel electrode substrate, and the common electrode substrate 28 is rubbed in the counterclockwise direction 36.
  • a reverse tilt domain occurs at the end of the pixel electrode 18 (a) on the right side of the pixel electrode substrate in the rubbing direction 26 with respect to 4.
  • the direction 38 in which the reverse tilt domain is likely to occur is oriented in the direction of the center line 34 between the pixel electrodes. It seems that the reverse tilt domain hardly occurs on both sides of the electrodes 18 (a) and 18 (b), but the rubbing direction 26 of the pixel electrode substrate faces the direction of the pixel electrode 18 (b). Therefore, a reverse tilt domain is generated in the pixel electrode 18 (b).
  • the rubbing direction 26 of the pixel electrode substrate is opposite to the rubbing direction 36 of the common electrode substrate. This is due to the spiral structure that rotates toward. That is, the direction 44 of the liquid crystal molecules at a position slightly above the pixel electrode substrate 27 is in a direction close to the rubbing direction 26 of the pixel electrode substrate, and is directed to the pixel electrode on the rubbing direction 26 side of the pixel electrode substrate. Reverse tilt domains are more likely to occur.
  • the reverse tilt domain can be brought closer to the pixel electrode center 34 by shifting the center of the common electrode absence part 33 in the rubbing direction 26 of the pixel electrode substrate.
  • the rubbing direction on the pixel electrode substrate 27 and the common electrode substrate 28 side can be specified by examining the tilt angle of the liquid crystal layer in contact with the lower alignment film 21 and the upper alignment film 22. That is, the direction in which the liquid crystal molecules have a tilt angle with respect to each substrate is the direction in which the rubbing process is performed.
  • a definitive method for measuring tilt angle is the crystal mouth-tissue method.
  • the reverse tilt domain can be further reduced by using a spontaneous helical pitch of the liquid crystal layer that is 6 to 10 times the thickness of the liquid crystal layer, which is shorter than before.
  • Twisted nematic liquid crystal has a pixel electrode base as described in Fig. 6.
  • the liquid crystal molecules 23 have a helical structure in which the orientation direction 44 of the liquid crystal molecules 23 rotates in a specific direction as the height from the plate 27 increases.
  • the spiral structure of twisted nematic liquid crystal can also be formed by the rubbing directions 26, 36 of the pixel electrode substrate 27 and the common electrode substrate 28, but the liquid crystal layer is spontaneously formed by liquid crystal molecules 23 called a chiral agent. It can be formed by adding a substance that gives rotational force.
  • the alignment direction of liquid crystal molecules 23 at a specific height from the pixel electrode substrate 27 is determined by the spontaneous rotational force of the liquid crystal molecules. This is the same as the orientation direction of the liquid crystal molecules 23 near 27.
  • the height of the liquid crystal molecules 23 from the pixel electrode substrate 27 at this time is the spontaneous spiral pitch.
  • the spontaneous spiral pitch of the liquid crystal layer was 12 times the thickness of the liquid crystal layer in order to lower the driving voltage of the liquid crystal display panel. 15 to 15 times longer.
  • FIG. 5 is a graph showing the relationship between the spontaneous spiral pitch and the width of the reverse tilt domain.
  • the horizontal axis in Fig. 5 is the length of the spontaneous spiral pitch.
  • the unit is z m.
  • the vertical axis is the distance from the edge of the pixel electrode 18 in the J-B tilt domain to the boundary between the reverse tilt domain and the normal display area (discrimination line), that is, the width of the reverse tilt domain. It is.
  • the unit is ⁇ m.
  • the thickness of the liquid crystal layer of the liquid crystal display device whose reverse tilt domain was measured was 3 m1.
  • the width of the reverse tilt domain can be reduced by reducing the spontaneous spiral pitch.
  • the spontaneous spiral pitch of the liquid crystal layer is shorter than that of the conventional liquid crystal layer.
  • the width of the reverse tilt domain was reduced by making it 10 times or less the thickness of the crystal layer.
  • the spontaneous spiral pitch is too small, it becomes difficult to control the orientation of the liquid crystal molecules 23 by the pixel electrode 18, so that the spontaneous spiral pitch of the liquid crystal layer is 6 to 1 times the thickness of the liquid crystal layer. A factor of 0 is optimal.
  • Japanese Patent Laid-Open Publication Nos. Hei 6-281959 and Hei 6-118447 describe that a slit is formed in a common electrode on a drain line of a thin film transistor. Since there is no idea to eliminate the reverse tilt domain at the electrode end, the configuration of the present invention in which the center of the portion where the common electrode electrode is absent is shifted from the center between adjacent pixel electrodes to the side where the reverse tilt domain occurs. was not described at all. Further, the above prior art did not describe a liquid crystal display device in which the spontaneous spiral pitch was increased from 6 times to 10 times the thickness of the liquid crystal layer.
  • FIG. 1 is a sectional view of a liquid crystal display device for explaining a basic configuration of the present invention.
  • FIG. 2 is a plan view of a pixel portion of a liquid crystal display device for explaining a basic configuration of the present invention.
  • FIG. 3 shows a state of an electric field of a liquid crystal display device employing the present invention. It is sectional drawing of a crystal display device.
  • FIG. 4 is a graph showing a comparison between the liquid crystal display device to which the present invention is applied and the conventional liquid crystal display device in terms of light blocking ability near the region between pixel electrodes.
  • FIG. 5 is a graph showing the relationship between the spontaneous spiral pitch and the width of the reverse tilt domain.
  • FIG. 6 (A) to 6 (E) are plan views of a pixel portion of a liquid crystal display device for explaining a direction in which a reverse tilt domain occurs.
  • FIG. 7 is a plan view of a pixel portion of the liquid crystal display device according to the first embodiment of the present invention.
  • FIG. 8 is a cross-sectional view of a pixel portion of the liquid crystal display device according to the first embodiment of the present invention.
  • FIG. 9 is a plan view of a display section of a liquid crystal display device showing the polarity of each pixel electrode in Embodiment 2 of the present invention.
  • FIG. 10 is a plan view of a pixel portion of a liquid crystal display device according to Embodiment 2 of the present invention.
  • FIG. 11 is a plan view of a display section of a liquid crystal display device showing the polarity of each pixel electrode in Embodiment 3 of the present invention.
  • FIG. 2 is a plan view of a pixel portion of a liquid crystal display device according to Embodiment 3 of the present invention.
  • FIG. 13 is a cross-sectional view showing a pixel portion of a conventional liquid crystal display device.
  • FIG. 14 is a plan view of a display section showing the polarity of each pixel electrode of the liquid crystal display device performing the line inversion drive.
  • FIG. 7 is a plan view of a liquid crystal display device according to an embodiment of the present invention
  • FIG. 8 is a cross-sectional view taken along line aa and line bb of FIG.
  • FIG. 7 is a plan view of the common electrode substrate 28 as viewed from above.
  • the present embodiment is directed to the display device described in the liquid of the line inversion driving method described above with reference to FIG. 14, and the pixel electrode 18 (a) of one row and the pixel of the adjacent row are used.
  • a slit-shaped electrode absent portion 33 is provided in the direction parallel to the scanning signal line (gate signal line) 8 in the direction 1, and the center of the electrode absent portion 33 is set to the center 3 between pixel electrodes parallel to the scanning signal line 8. 4 is shifted in the rubbing direction 26 on the side where the reverse tilt domain occurs, that is, on the pixel electrode substrate side.
  • the slit-shaped electrode-free portion 33 is located in the pattern of the light shields 4 and 9 or
  • a light shielding metal layer such as a capacitor electrode 4 formed on a thin film transistor substrate (pixel electrode substrate) 27.
  • the distribution of the equipotential lines 40 changes as described in FIG. 3, and as a result, FIG. As described above, the region of the reverse tilt 25 can be closer to the center 34 between the pixel electrodes than the conventional case.
  • the area where the reverse tilt domain 32 is hidden by the light shields 4 and 9 can be narrowed, so that the opening can be widened and a bright image display can be obtained.
  • Reference numeral 27 in FIG. 8 denotes a pixel electrode substrate (TFT substrate, first substrate) made of a transparent insulator such as quartz glass or glass having a softening point of 1000 ° C. or less.
  • 1 is a base film (first insulating film), S i 0 2, S i N, a transparent insulating film such as Ta 2 0 5, AL 2 0 3, an alkali component contained in the pixel electrode substrate is a liquid Akirachu (4) Provided to prevent leakage into the semiconductor layer of the thin film transistor.
  • Reference numeral 2 denotes a first light-shielding film (backside light-shielding layer, TFT substrate light-shielding film), which comprises a light-shielding metal layer such as Cr, Al, Ta, and Mo, and a light-shielding insulating layer obtained by adding a dye or pigment to an insulating film.
  • the semiconductor layer in the TFT channel is shielded from light to prevent TFT malfunction.
  • 3 is a second insulating film, S i 0 2, S i N, with Ta 2 0 5, AL 2 0 3 transparent insulating film such as is provided with a TFT substrate light-shielding film 2 and the TFT for insulation .
  • Reference numeral 4 denotes a first capacitor electrode (capacitor forming layer), which is formed of a metal layer such as Cr, A1, Ta, and Mo, and is one of the components of a storage capacitor 20 that holds the potential of the pixel electrode 18.
  • the first capacitor electrode 4 also functions as a light-shielding film (second light-shielding film) of the TFT substrate 27, and also has a function of shielding the reverse tilt domain 32 and the common electrode absent portion 33 from light.
  • Reference numeral 6 denotes a semiconductor layer, which functions as a channel layer of the TFT 19 and one electrode (second capacitor electrode) of the storage capacitor 20.
  • a material of the semiconductor layer 6 there can be used a polysilicon formed by a low pressure CVD method, a polysilicon formed by irradiating an amorphous silicon film with a laser beam, or an amorphous silicon film formed by a plasma CVD method.
  • Reference numeral 7 denotes a gate insulating film (fourth insulating film) made of SiO 2 , Si N, and the like, and functions as a dielectric of the storage capacitor 20 in addition to the gate insulating film of the TFT 19.
  • 8 is a gate electrode layer, such as a polysilicon or metal layer.
  • a gate electrode of TFT 19 a gate wiring (scanning signal line), and the other electrode of the storage capacitor 20 (third capacitor electrode).
  • Reference numeral 9 denotes a source / drain electrode layer, which is made of a metal layer such as Cr, A1, Ta, Mo, etc., and has a source electrode, a drain electrode, a video signal line (drain wiring), and a storage capacitor 20 of TFT 19.
  • One electrode (the fourth capacitance electrode) is formed.
  • the side connected to 8 will be referred to as the source electrode.
  • the S i 0 2, S i N consists T a 2 0 5, AL 2 0 3 or the like transparent insulating film, the gate wiring 8 and the drain line 9 Acts as a dielectric for insulation and storage capacitance 20.
  • 1 1 is an interlayer insulating film (the sixth insulating film), S i 0 2, S i N, consists T a 2 0 5, AL 2 0 3 or the like transparent insulating film, wiring layers 1 to be described later 2 and the drain electrode 9 and the gate wiring 8 are insulated.
  • Reference numeral 12 denotes a wiring layer, which is formed of a conductive film such as Cr, AI, Ta, Mo, molybdenum silicide, and tungsten silicide, and electrically connects the source electrode 9 and the pixel electrode 18.
  • the wiring layer 12 also functions as a light-shielding film (third light-shielding film) that shields the gap between the storage capacitor electrodes 4 and 9 and the gate wiring 8.
  • Reference numeral 13 denotes an interlayer insulating film (seventh insulating film), which is made of SiO 2 , and insulates the pixel electrode 18 (a) of an adjacent pixel from the wiring layer 12.
  • Reference numeral 14 also denotes an interlayer insulating film (eighth insulating film) made of SiN, and insulates the pixel electrode 18 (a) of the adjacent pixel from the wiring layer 12.
  • Reference numeral 15 denotes a flattening film (a ninth insulating film), which is a transparent insulating resin such as polyimide-epoxy, a photosensitive transparent organic film such as a photoresist, or a relatively thick Si 0 2
  • the pixel electrode 18 is made of a transparent inorganic insulating film such as a film or a sine film, and the surface on which the pixel electrode 18 is formed is made flat so that the electric field generated by the pixel electrode 18 becomes a uniform vertical electric field.
  • 18 is the pixel electrode, I TO (indium tin It is made of a transparent conductive film such as oxide), and controls the alignment direction by applying an electric field to the liquid crystal molecules 23 to change the light transmittance of the liquid crystal layer to display an image.
  • 18 (b) shows one pixel electrode
  • 18 (a) shows a pixel electrode adjacent in the vertical direction (y direction, column direction).
  • Reference numeral 17 denotes a contact hole formed in each insulating film to connect between the electrodes.
  • 17 (A) denotes the drain electrode 9 and the semiconductor layer 6, and 17 (D) denotes the source electrode 9 and the semiconductor layer 6, 1.
  • 7 (B) is a contact hole connecting the source electrode 9 and the wiring layer 12
  • 17 (C) is a contact hole connecting the wiring layer 12 and the pixel electrode 18.
  • Reference numeral 21 denotes an alignment film (lower alignment film, first alignment film) provided on the TFT substrate 27, which is made of an organic film such as polyimide.
  • the lower alignment film 21 is rubbed in the direction indicated by reference numeral 26 in FIG.
  • Reference numeral 23 schematically depicts the state of the liquid crystal molecules.
  • 24 is a tilt angle generated by the rubbing process 26 of the TFT substrate.
  • Reference numeral 25 denotes a reverse tilt generated by a horizontal electric field between the adjacent pixel electrodes 18 (a) and 18 (b).
  • Reference numeral 32 denotes an area where reverse tilt occurs, that is, a reverse tilt domain.
  • 34 is a center line between adjacent pixel electrodes.
  • Reference numeral 28 denotes a common electrode substrate (opposite substrate, second substrate) made of a transparent insulator such as glass or plastic.
  • insulating film 8 insulating film
  • a transparent insulating film such as AL 2 0 3
  • line insulation of the common electrode 31 and the black matrix It functions to prevent dyes, pigments, carbon, etc. in black matrix from entering the liquid crystal layer.
  • Reference numeral 31 denotes a common electrode (opposite electrode), which functions as a transparent conductive film such as an ITO and generates a vertical electric field in the liquid crystal layer together with the pixel electrode 18.
  • Reference numeral 22 denotes an alignment film (upper alignment film, second alignment film) provided on the common electrode substrate 28, which is made of an organic film such as polyimide. The upper alignment film 22 is rubbed in the direction indicated by reference numeral 36 in FIG.
  • Reference numeral 33 denotes an electrode absent portion provided on the common electrode 31.
  • Reference numeral 35 denotes the center line of the common electrode absence part.
  • the common electrode 31 is electrically connected in some places by a common electrode connection part 37 so as not to be electrically disconnected by the electrode absence part 33. In the common electrode connection part 37, the effect of narrowing the width of the reverse tilt domain is small, but in this embodiment, since the common electrode connection part 37 is provided on each drain line 9, the reverse tilt domain is The problem of light leakage does not occur because it is hidden by 9.
  • the planar structure of this embodiment includes a plurality of scanning signal lines 8 extending in the horizontal direction (X direction, row direction) and a plurality of scanning signal lines 8 extending in the vertical direction (y direction, column direction).
  • An active matrix configuration is provided in which a pixel including a thin film transistor 19 and a pixel electrode 18 is provided corresponding to a portion where the video signal line 9 intersects.
  • capacitance lines 4 and 8 extending in the same direction as the scanning signal line 8.
  • the capacitor lines 4 and 8 form a storage capacitor 20 together with the pixel electrode 18 and the source electrode 9 and serve to hold the display voltage applied to the pixel electrode 18 for a certain period.
  • the vertical structure of the storage capacitor 20 is as follows: the first capacitance electrode (capacitance line) 4, the third insulation film 5, the second capacitance electrode (semiconductor layer) 6, the fourth insulation film (gate insulation). It has a multilayer structure consisting of a film 7, a third capacitor electrode (capacitance line) 8, a fifth insulating film (interlayer insulating film) 10, and a fourth capacitor electrode (source electrode) 9.
  • the first capacitance electrode 3 and the third capacitance electrode 8 are connected to the capacitance line, and the second capacitance electrode 6 and the fourth capacitance electrode 9 are connected to the pixel electrode 18 so that the pixel electrode 18 and the capacitance line 4 are connected.
  • a multilayer capacitive element is formed therebetween.
  • each storage capacitor electrode 4, 6, 8, and 9 can be reduced, and the aperture ratio of the pixel can be improved. Can be done.
  • a liquid crystal display device used in liquid crystal projectors and the like, in which the diagonal length of the display area is 5.08 cm or less (2 inches or less), the size of the pixel electrode becomes extremely small, so the storage capacitance is reduced.
  • the use of a multi-layer structure is extremely effective for obtaining a bright image display.
  • a liquid crystal display device with a diagonal display area of 27.94 cm or less (11-inch or less) used in small notebooks and personal computers has a pixel count of 102 4 X
  • a high-definition low-temperature polysilicon TFT liquid crystal display device with a specification of 3 X 768 or more (XGA or more) the size of the pixel electrode becomes extremely small. Is particularly effective for increasing the number of pixels of the liquid crystal display device and increasing the definition.
  • the storage capacitor 20 is moved near the scanning signal line 8 in order to hide the reverse tilt domain.
  • the rubbing direction 26 on the TFT substrate side is directed 45 degrees to the lower left with respect to the center line of the scanning signal line 8. Therefore, as shown in FIG. 6 (D), a reverse tilt domain 32 is generated at the end of the pixel electrode 18 (b) below the center 34 between the pixel electrodes. Therefore, by providing the storage capacitance element 20 at the end of the pixel electrode 18 (a) near the lower side of the scanning signal line 8, the capacitance electrodes 4 and 9 function as a light shielding film and the reverse tilt domain 3 2 The problem of light leakage does not occur.
  • the elongated slit-shaped electrode-free portion 33 provided on the common electrode 31 along the scanning signal line 8 is located below the pixel electrode center 34, that is, the rubbing direction on the TFT substrate side. Since the reverse tilt domain 3 2 can be made smaller, the reverse tilt domain 3 Since 2 can be confined in the region where the capacitor electrodes 4 and 9 are provided, it is not necessary to increase the area of the capacitor electrodes 4 and 9 more than necessary, and the aperture ratio is further improved.
  • the electrode absent portion 33 is provided in the region where the capacitor electrode 4 exists, the electrode absent portion 33 is not conspicuous and the display image quality is not degraded.
  • the gap between the capacitance electrodes 4 and 9, the scanning signal line 8, and the TFT substrate light-shielding film 2 is shielded by the wiring layer 12 made of the light-shielding metal layer, so that light leakage occurs between them.
  • the contrast is improved without any.
  • the reverse tilt domain 32 and the pixel electrode absent portion 33 are also shielded from light by the wiring layer 12.
  • the rubbing direction 26 on the TFT substrate side is provided 45 degrees to the lower left with respect to the center line of the scanning signal line 8, and
  • the rubbing direction 36 on the electrode substrate side is provided 45 degrees to the lower right, so as shown in Fig. 6 (D).
  • the width of the reverse tilt domain is minimized, and the aperture ratio is further improved.
  • a reverse tilt domain is likely to be generated between the pixel electrodes 18 adjacent in the row direction (the X direction and the horizontal direction). Since the line inversion driving method described with reference to FIG. 14 is used, the pixel electrodes 18 adjacent in the row direction have the same polarity, so the horizontal electric field component generated between the pixel electrodes 18 adjacent in the row direction. Is weak, and no reverse tilt domain occurs at the end of the pixel electrode 18 in the row direction.
  • the semiconductor layer 6 in the channel portion of the TFT is shielded from light by the drain signal line 9, so that the TF T does not malfunction due to external light.
  • a storage capacitor type liquid crystal display device having a configuration in which the scanning signal line 8 and the capacitor lines 4 and 8 are provided separately is described as an example, but the present invention is directed to a storage capacitor type liquid crystal display device.
  • the present invention is not limited to the display device, and can be applied to an additional capacitance type liquid crystal display device in which the scanning signal lines 8 of adjacent pixels and the capacitance lines 4 and 8 are integrally formed.
  • the additional capacitance type liquid crystal display device since the scanning signal line 8 of the adjacent pixel is also used as the capacitance lines 4 and 8, the aperture ratio of the pixel can be further improved.
  • the additional capacitance type liquid crystal display device has a disadvantage that the load of a driver for driving the scanning signal line 8 becomes heavy because the storage capacitor 20 is connected to the scanning signal line 8, and the scanning signal line 8 can be operated at high speed.
  • the storage capacitor type is more advantageous for a high-definition liquid crystal display device that needs to be driven and has a large number of scanning lines.
  • the noise component jumping into the pixel electrode 18 from the video signal line 9 via the parasitic capacitance is canceled by the polarity inversion of the video signal.
  • a uniform image display can be obtained between pixels in different columns.
  • the spontaneous spiral pitch of the liquid crystal layer is about 20 ⁇ m, which is 6 to 10 times the thickness of the liquid crystal layer.
  • the width of the reverse tilt domain can be reduced by about 0.8 ⁇ 10 as compared with the case of using about 60 ⁇ m, which is equivalent to about 15 times.
  • the contact hole 17 (C) for connecting the pixel electrode 18 to the wiring 12 is provided apart from the edge of the pixel electrode 18, so that the contact hole The transverse electric field near 17 (C) is weakened, and the reverse tilt domain that occurs near the contact hole 17 (C) can be reduced. More specifically, as shown in Fig. 8, The cross-sectional shape of the pixel electrode 18 on the contact hole 17 (C) formed in the film 15 is not flat but deeper than other portions. Therefore, the liquid crystal molecules on the contact hole 17 (C) are far from the common electrode 31 and are susceptible to the lateral electric field, and are liable to cause reverse tilt as shown at 23a.
  • a column-by-column inversion drive type liquid crystal in which the polarity of the pixel electrodes 18 (a) and 18 (b) is inverted for each column to drive the liquid crystal display device. It is an embodiment when the present invention is applied to a display device.
  • FIG. 10 is a plan view of a pixel portion of a liquid crystal display device according to Embodiment 2 of the present invention.
  • the reference numerals are the same as those in FIG. 7 described in the first embodiment.
  • the present embodiment is characterized in that the electrode absent portion 33 provided on the common electrode 31 is provided in a slit shape along the video signal line 9.
  • the rubbing direction 26 on the TFT substrate side is directed to the lower right direction by 45 degrees with respect to the center line of the scanning signal line 8
  • the rubbing direction 36 on the common electrode substrate side is directed to the upper right direction by 45 degrees. I have. Accordingly, FIG. 6 (D) is rotated counterclockwise by 90 degrees, and a reverse tilt domain 32 is generated at the end of the pixel electrode 18 (b) on the right side with respect to the center 34 between the pixel electrodes.
  • the center 35 of the common electrode absence part is shifted to the side where the reverse tilt domain occurs, that is, to the right side, from the center 34 between the pixel electrodes.
  • the reverse tilt domain is moved toward the pixel electrode center 34 side.
  • the reverse tilt domain is shielded from light by the black matrix 29 provided on the common electrode substrate 28.
  • the area to be shielded by the black matrix 29 can be reduced, so that the aperture ratio is improved.
  • the black matrix 29 shields the common electrode absent portion 33 from light, so that the common electrode absent portion 33 is inconspicuous and the display quality is improved.
  • the capacitor 20 may be provided along the video signal line 9, and the reverse tilt domain generated along the video signal line 9 may be shielded by the capacitor 20.
  • the connecting portion 37 electrically connecting the common electrode 31 is provided on the scanning signal line 8. Is provided.
  • the noise component jumping into the pixel electrode 18 from the scanning signal line 8 via the parasitic capacitance is offset by the polarity inversion of the pixel electrode 18. Therefore, uniform image display can be obtained between pixels in different rows.
  • the spontaneous spiral pitch of the liquid crystal layer is about 20 2m, which is 6 to 10 times the thickness of the liquid crystal layer.
  • the width of the reverse tilt domain can be reduced by about 0.1 as compared with the case of using about 60 / zm which is twice to 15 times.
  • the contact hole 17 (C) for connecting the pixel electrode 18 to the wiring 12 is provided away from the edge of the pixel electrode 18, so that the contact hole 11 (C) is provided.
  • the transverse electric field near (C) is weakened, and the reverse tilt domain generated near contact hole 17 (C) can be reduced.
  • the polarity of the pixel electrodes 18 (a) and 18 (b) is inverted for each row, and the pixel electrodes 18 (b) and 18 (
  • FIG. 12 is a plan view of a pixel portion of a liquid crystal display device according to Embodiment 3 of the present invention.
  • the reference numerals are the same as those in FIG. 7 described in the first embodiment.
  • the common electrode 31 is provided with a slit-shaped electrode absent portion 33 (a) along the scanning signal line 8 and a video signal line 9 with a slit-shaped electrode absent portion 33 (b).
  • the feature is that it is provided.
  • the rubbing direction 26 on the TFT substrate side is directed to the lower right direction (direction in which the light shielding film 4 is provided) by 45 degrees with respect to the center line of the scanning signal line 8, and the rubbing direction 36 on the common electrode substrate side. Is directed to the upper right direction by 45 degrees (the direction in which the light shielding film 4 is not provided with respect to the center line of the scanning signal line 8). Accordingly, the center 34 between the pixel electrodes adjacent in the column direction has the same shape as that shown in FIG. 6 (B), and the reverse tilt is applied to the end of the pixel electrode 18 (b) below the center 34 between the pixel electrodes. Domain 32 occurs.
  • the capacitive element 20 is provided on the scanning signal line 8 on the side where the reverse tilt domain occurs, and the reverse tilt domain is shielded from light.
  • the center 34 4 ′ between the pixel electrodes adjacent in the row direction has the same shape as that of FIG. 6D rotated 90 degrees counterclockwise.
  • a reverse tilt domain 32 is generated at the end of the pixel electrode 18 (b) on the right side with respect to 4 ′. Therefore, in the present embodiment, the center 35 'of the common electrode absence part extending in the column direction is shifted to the side where the reverse tilt domain occurs, that is, to the right side, from the center 34' between the pixel electrodes, so that the reverse tilt domain is shifted. It is close to the pixel electrode center 34, side.
  • the reverse tilt domain generated at the end of the pixel electrode 18 (b) along the video signal line 9 is shielded from light by a black matrix 29 extending along the video signal line 9.
  • the capacitor 20 may be provided along the video signal line 9, and the reverse tilt domain generated along the video signal line 9 may be shielded by the capacitor 20.
  • the area for shielding the reverse tilt domain with the capacitive element 20 and the black matrix 29 can be reduced, and the aperture ratio is improved.
  • the common electrode non-existing portions 3 3 (a) and 33 (b) are shielded from light by the capacitive element 20 and the black matrix 29, the common electrode non-existing portions are inconspicuous, and the display image quality is reduced. Is improved.
  • the slits 33 (a) and 33 (b) are provided along the scanning signal line 8 and the video signal line 9 on the common electrode 31.
  • a connection portion 37 for electrically connecting the electrodes 31 is provided on the scanning signal line 8 and the video signal line.
  • the width of the reverse tilt domain generated along the video signal line 9 is the smallest, so that the area shielded by the black matrix 29 is smaller.
  • the aperture ratio is improved, and the brightest image display is obtained.
  • the width of the reverse tilt domain generated along the scanning signal line 8 is not minimum, but generally, the interval between the video signal lines 9 is narrower than the interval between the scanning signal lines 8. (For example, in the case of color pixels, R, G, and B pixels are arranged in the row direction to make one pixel.) Therefore, it is better to minimize the width of the reverse tilt domain generated along the video signal line 9.
  • the definition of the liquid crystal display device can be increased.
  • the noise component that jumps from the video signal line 9 to the pixel electrode 18 through the parasitic capacitance of the video signal line 9 and the pixel electrode 18 is: The signal is canceled by the reversal of the polarity of the video signal.
  • the noise component that jumps into the pixel electrode 18 from 8 is canceled by the polarity inversion of the pixel electrode 18, so that a uniform image display can be obtained between pixels in different rows and columns, and the most uniform display image can be obtained. Are better.
  • the first embodiment described above does not generate a reverse chinoreto domain along the video signal line 9, so that the video signal line 9 This is advantageous because the distance between the two can be minimized.
  • the spontaneous spiral pitch of the liquid crystal layer is about 20 2m, which is 6 to 10 times the thickness of the liquid crystal layer. Use of about 60 m, which is double to 15 times Compared with the case, the width of the reverse tilt domain can be reduced by about 0.1.
  • the contact hole 17 (C) for connecting the pixel electrode 18 to the wiring 12 is provided away from the edge of the pixel electrode 18, so that the contact The transverse electric field near the contact hole 17 (C) is weakened, and the reverse tilt domain generated near the contact hole 17 (C) can be reduced.
  • the present invention reduces the width of a reverse tilt domain generated at the edge of a pixel electrode of a liquid crystal display device, prevents light leakage, improves display contrast, and reduces the light blocking width of the reverse tilt domain to increase the aperture ratio. It is possible to improve the brightness and obtain a display image, which is a practical possibility.

Abstract

L'invention concerne un dispositif d'affichage à cristaux liquides qui permet la réduction de la largeur d'un domaine d'inclinaison inverse causant un défaut d'image, tel que des fuites de lumière, et des améliorations du contraste de son affichage et de son rapport d'ouverture. Une partie non existante d'une électrode commune qui correspond à un espacement entre une électrode de pixel et une électrode de pixel adjacente à celle-ci est formée dans une électrode commune qui fait face aux électrodes de pixel, une couche de cristal liquide se trouvant entre ces électrodes dans le dispositif d'affichage à cristaux liquides et le centre de la partie non existante de l'électrode commune est déplacée du centre de l'espacement entre les électrodes de pixel dans le sens de frottement d'un substrat d'électrode de pixel.
PCT/JP2000/001861 2000-03-27 2000-03-27 Dispositif d'affichage a cristaux liquides WO2001073507A1 (fr)

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PCT/JP2000/001861 WO2001073507A1 (fr) 2000-03-27 2000-03-27 Dispositif d'affichage a cristaux liquides

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003195312A (ja) * 2001-12-27 2003-07-09 Hannstar Display Corp 偏曲垂直アラインメント・モードの液晶表示器
JP2003330036A (ja) * 2002-05-10 2003-11-19 Seiko Epson Corp 電気光学装置及び半導体装置の製造方法
US10184670B2 (en) 2009-11-05 2019-01-22 Winstone Wallboards Limited Heating panel and method therefor

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0396919A (ja) * 1989-09-11 1991-04-22 Matsushita Electric Ind Co Ltd 液晶表示装置
JPH04186227A (ja) * 1990-11-20 1992-07-03 Nec Corp アクティブマトリックス液晶表示素子
JPH09311349A (ja) * 1996-05-23 1997-12-02 Casio Comput Co Ltd 液晶表示素子
JPH09318937A (ja) * 1996-05-24 1997-12-12 Casio Comput Co Ltd 液晶表示素子
JPH10104664A (ja) * 1996-08-05 1998-04-24 Sharp Corp 液晶表示装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0396919A (ja) * 1989-09-11 1991-04-22 Matsushita Electric Ind Co Ltd 液晶表示装置
JPH04186227A (ja) * 1990-11-20 1992-07-03 Nec Corp アクティブマトリックス液晶表示素子
JPH09311349A (ja) * 1996-05-23 1997-12-02 Casio Comput Co Ltd 液晶表示素子
JPH09318937A (ja) * 1996-05-24 1997-12-12 Casio Comput Co Ltd 液晶表示素子
JPH10104664A (ja) * 1996-08-05 1998-04-24 Sharp Corp 液晶表示装置

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003195312A (ja) * 2001-12-27 2003-07-09 Hannstar Display Corp 偏曲垂直アラインメント・モードの液晶表示器
JP4541633B2 (ja) * 2001-12-27 2010-09-08 瀚宇彩晶股▲ふん▼有限公司 偏曲垂直アラインメント・モードの液晶表示器
JP2003330036A (ja) * 2002-05-10 2003-11-19 Seiko Epson Corp 電気光学装置及び半導体装置の製造方法
US10184670B2 (en) 2009-11-05 2019-01-22 Winstone Wallboards Limited Heating panel and method therefor

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