WO2012118006A1 - Dispositif d'affichage à cristaux liquides - Google Patents

Dispositif d'affichage à cristaux liquides Download PDF

Info

Publication number
WO2012118006A1
WO2012118006A1 PCT/JP2012/054747 JP2012054747W WO2012118006A1 WO 2012118006 A1 WO2012118006 A1 WO 2012118006A1 JP 2012054747 W JP2012054747 W JP 2012054747W WO 2012118006 A1 WO2012118006 A1 WO 2012118006A1
Authority
WO
WIPO (PCT)
Prior art keywords
liquid crystal
crystal display
crystal layer
pair
layer
Prior art date
Application number
PCT/JP2012/054747
Other languages
English (en)
Japanese (ja)
Inventor
昌行 兼弘
松本　俊寛
雄一 川平
Original Assignee
シャープ株式会社
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 シャープ株式会社 filed Critical シャープ株式会社
Publication of WO2012118006A1 publication Critical patent/WO2012118006A1/fr

Links

Images

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
    • G02F1/134363—Electrodes characterised by their geometrical arrangement for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1341—Filling or closing of cells
    • G02F1/13415—Drop filling process

Definitions

  • the present invention relates to a liquid crystal display. More specifically, the present invention relates to a liquid crystal display suitable for a transverse bend alignment (TBA) mode.
  • TSA transverse bend alignment
  • a liquid crystal display is a display device with low power consumption, and can be reduced in weight and thickness, so that it is widely used for televisions, monitors for personal computers, and the like.
  • the display method of the liquid crystal display is determined by how the liquid crystals (liquid crystal compounds) are arranged.
  • Conventionally used liquid crystal display methods include, for example, a TN (TwistedistNematic) mode liquid crystal display or a VA (Vertical Alignment) mode in which an electric field in a direction perpendicular to the substrate is applied to align liquid crystals. Can be mentioned.
  • a display method in which an electric field (lateral electric field) in a direction parallel to the substrate is applied to align liquid crystals see, for example, Patent Document 1), or a horizontal electric field is applied to liquid crystal with vertical alignment is driven.
  • TSA transverse bend alignment
  • the liquid crystal display includes a liquid crystal layer 230 sandwiched between a pair of transparent substrates 211 and 221.
  • a common electrode 216, a dielectric layer 218, a pixel electrode 215, and an alignment film 212 are formed in this order on the liquid crystal layer side main surface of the transparent substrate 211, and a polarizing plate 241 is attached to the opposite main surface.
  • an alignment film 222 is formed on the main surface of the transparent substrate 221 on the liquid crystal layer side, and a polarizing plate 251 is attached to the main surface on the opposite side. As shown in FIG.
  • an electric field (lateral electric field) in a direction parallel to the transparent substrates 211 and 221 is applied to the liquid crystal layer 230 by the pixel electrode 215 and the common electrode 216, and the liquid crystal is aligned.
  • the specific resistance of the liquid crystal is 1 ⁇ 10 9 ⁇ ⁇ cm or more and 1 ⁇ 10 14 ⁇ ⁇ cm or less.
  • a lateral electric field is applied to a liquid crystal having positive dielectric anisotropy and aligned in a vertical direction in a state where no voltage is applied.
  • the present invention has been made in view of the above situation, and an object of the present invention is to provide a TBA mode liquid crystal display in which display defects such as flicker and burn-in caused by a liquid crystal layer are unlikely to occur.
  • the cause is impurity ions in the liquid crystal layer.
  • flicker is generated when a direct current component due to impurity ions rides on an alternating current signal for driving the liquid crystal and the alternating current signal is not symmetric.
  • image sticking occurs due to an electric field generated by accumulation of impurity ions in the liquid crystal layer at the interface between the alignment film and the liquid crystal layer.
  • the inventors of the present invention have focused on the fact that the liquid crystal material is deteriorated by ultraviolet irradiation, and as a result, impurity ions are generated.
  • the impurity ions are: (1) a liquid crystal produced by a liquid crystal dropping method (ODF; One drop fill process) in which a seal pattern is formed by an ultraviolet curable sealing material. It has been found that this occurs due to the ultraviolet rays irradiated in the manufacturing process of the display, or (2) the manufacturing process of the liquid crystal display which has an inlet and is sealed with an ultraviolet curable resin.
  • ODF liquid crystal dropping method
  • impurity ions generated in the liquid crystal layer due to ultraviolet rays irradiated in the manufacturing process of the liquid crystal display will be described as an example.
  • FIG. 8 is a schematic cross-sectional view of a liquid crystal display in a mode in which liquid crystal molecules are vertically aligned with respect to a substrate during ultraviolet irradiation in the liquid crystal dropping method.
  • the common electrode 116 is formed on the liquid crystal layer 130 side of the transparent substrate 121, and the alignment film 122 is further formed on the common electrode 116 (liquid crystal layer 130 side). To do.
  • a dielectric layer 118 is formed on the liquid crystal layer 130 side of the transparent substrate 111, a pixel electrode 115 is formed on the dielectric layer 118 (liquid crystal layer 130 side), and further on the pixel electrode 115 (liquid crystal layer 130 side).
  • An alignment film 112 is formed.
  • an ultraviolet curable sealant is applied to one of the transparent substrates 111 and 121 to form a seal pattern 123.
  • a fine droplet of a liquid crystal material is dropped and applied onto the entire surface of the transparent substrate 111 or 121 on which the seal pattern 123 is formed with the UV curable sealing material being uncured, and the other transparent substrate is overlaid. As shown in FIG. 3, the seal pattern 123 is cured by irradiating with an ultraviolet ray 106.
  • the ultraviolet curable sealing material has thermosetting properties in addition to ultraviolet curable properties, it is further heated to perform the main curing.
  • a color filter layer may exist between the transparent substrate 121 and the common electrode 116, and the unevenness of the color filter layer itself is flattened between the color filter layer and the common electrode 116, and the color filter layer There may be a dielectric layer for preventing elution of impurities.
  • the liquid crystal dropping method the liquid crystal material is dropped directly onto the transparent substrate, so that the liquid crystal display can be manufactured in a shorter time than the liquid crystal injection method in which the liquid crystal material is injected by capillary action.
  • FIG. 9 is a schematic cross-sectional view of a TBA mode liquid crystal display after ultraviolet irradiation manufactured by a liquid crystal dropping method.
  • ultraviolet rays are irradiated to cure the seal pattern 123 made of the ultraviolet curable sealing material.
  • the seal pattern 123 made of the ultraviolet curable sealing material.
  • the liquid crystal layer 130 is irradiated with ultraviolet rays.
  • impurity ions 131 are generated from the liquid crystal compound 105 included in the liquid crystal layer 130.
  • the liquid crystal layer near the injection port may be irradiated with ultraviolet rays to generate impurity ions.
  • the present inventors have found that flicker and image sticking become noticeable when the amount of impurity ions generated exceeds a predetermined amount. Furthermore, when the generation amount of impurity ions due to ultraviolet rays is relatively large, the resistance of the liquid crystal layer becomes small, so that the specific resistance of the liquid crystal layer becomes small. Conversely, the generation amount of impurity ions due to ultraviolet rays is small. It has been found that when the amount is relatively small, the specific resistance of the liquid crystal layer increases because the resistance of the liquid crystal layer increases. At the same time, the inventors have a correlation between the specific resistance of the liquid crystal layer and the residual DC voltage, and when the residual DC voltage is 200 mV or less, there is no flicker or burn-in that reduces display performance. I found.
  • the present inventors can simultaneously reduce the residual DC voltage to 200 mV or less by forming a liquid crystal layer using a liquid crystal material having a specific resistance of at least 1.5 ⁇ 10 14 ⁇ ⁇ cm or more. The inventors have found that the occurrence of flicker and / or burn-in can be suppressed and have conceived that the above-mentioned problems can be solved brilliantly, and have reached the present invention.
  • an aspect of the present invention is a liquid crystal display including a pair of substrates and a liquid crystal layer sandwiched between the pair of substrates, wherein the liquid crystal compound included in the liquid crystal layer is the pair of substrates when no voltage is applied.
  • the substrate is oriented substantially perpendicularly to the substrate surface, and one of the pair of substrates has a pair of electrodes, and the pair of electrodes are opposed to each other with a gap in plan view.
  • the orientation of the liquid crystal compound is controlled by the electric field generated by the electrode, the dielectric anisotropy of the liquid crystal layer is positive, and the liquid crystal layer has a specific resistance of 1.5 ⁇ 10 14 ⁇ ⁇ cm or more.
  • a liquid crystal display (hereinafter also referred to as “liquid crystal display of the present invention”).
  • the liquid crystal compound contained in the liquid crystal layer is aligned substantially perpendicular to the pair of substrate surfaces when no voltage is applied” specifically means that the pretilt angle of the liquid crystal layer is It is more preferably 86 ° (more preferably 88 °) or more and 90 ° or less. If the angle is less than 86 °, the front contrast is significantly reduced.
  • the configuration of the liquid crystal display of the present invention is not particularly limited by other components as long as such components are essential.
  • the dielectric constant anisotropy ⁇ of the liquid crystal layer is preferably 15 ⁇ ⁇ ⁇ 25 at 25 ° C.
  • Such a liquid crystal layer can be suitably used for the liquid crystal display of the present invention.
  • the liquid crystal layer preferably has a specific resistance change rate of 32% or less before and after UV irradiation, and the specific resistance change rate is preferably as small as possible.
  • the small change rate of the specific resistance before and after the ultraviolet irradiation means that the amount of impurity ions generated by the ultraviolet irradiation is small, and the deterioration of display quality such as image sticking and flicker is more effectively suppressed. be able to.
  • the other of the pair of substrates (the one of the pair of substrates that does not have the pair of electrodes) preferably includes an electrode that covers at least the display region. Thereby, an oblique electric field can be applied to the liquid crystal layer. That is, the alignment of the liquid crystal compound in the liquid crystal layer can be controlled by this electrode and the pair of electrodes. Moreover, the response speed can be improved.
  • the liquid crystal display of the present invention preferably has a sealing member that encloses the liquid crystal layer (or liquid crystal) between the pair of substrates, and the sealing member does not have a liquid crystal inlet sealing member.
  • a liquid crystal display that does not have an injection port for injecting liquid crystal material between substrates drops liquid crystal material on one of a pair of substrates, and seals the substrate on which the liquid crystal material is dropped with the other substrate.
  • the liquid crystal layer may be irradiated with ultraviolet rays that are irradiated to cure the sealing material. At this time, even if the liquid crystal layer is irradiated with ultraviolet rays, flicker and image sticking can be suppressed if the specific resistance of the liquid crystal layer is 1.5 ⁇ 10 14 ⁇ ⁇ cm or more.
  • the liquid crystal display in which the liquid crystal layer may be damaged by the ultraviolet irradiation in the manufacturing process it is possible to particularly suitably suppress the deterioration of the display characteristics.
  • Another aspect of the present invention is surrounded by (1) a step of applying an ultraviolet curable sealing material (ultraviolet curable sealing material) to the first substrate, and (2) the sealing material of the first substrate. Or a step of dropping a liquid crystal material into a region of the second substrate facing the region surrounded by the sealing material of the first substrate, and (3) the first substrate so that the liquid crystal material is interposed A step of bonding a second substrate to one substrate; and (4) irradiating the sealing material between the first substrate and the second substrate bonded to each other with ultraviolet rays to cure the sealing material.
  • an ultraviolet curable sealing material ultraviolet curable sealing material
  • a liquid crystal display manufacturing method including a step, wherein a specific resistance of the liquid crystal layer made of the liquid crystal material after the step (4) is 1.5 ⁇ 10 14 ⁇ ⁇ cm or more (hereinafter referred to as a liquid crystal display manufacturing method).
  • Method of manufacturing the liquid crystal display of the present invention also referred to as ".) A.
  • the sealing material is irradiated with ultraviolet rays.
  • the liquid crystal layer may be irradiated with ultraviolet rays.
  • the specific resistance of the liquid crystal layer after ultraviolet irradiation is kept at 1.5 ⁇ 10 14 ⁇ ⁇ cm or more, even if the liquid crystal layer is irradiated with ultraviolet rays, display defects such as flicker and burn-in may occur.
  • production can be suppressed. Therefore, the manufacturing method of the liquid crystal display of this invention can be used suitably for the manufacturing method of the liquid crystal display accompanied by ultraviolet irradiation.
  • the manufacturing method of the liquid crystal display of the present invention is not particularly limited by other steps as long as such a step (in particular, a step of irradiating the sealing material with ultraviolet rays) is included as an essential step. Moreover, the preferable form in the liquid crystal display of this invention is applicable also to the manufacturing method of the liquid crystal display of this invention.
  • the present invention it is possible to provide a liquid crystal display in which display defects such as flicker and burn-in are unlikely to occur, and a manufacturing method thereof.
  • FIG. 3 is a schematic plan view of the liquid crystal display of Embodiment 1.
  • FIG. FIG. 2 is a schematic cross-sectional view taken along the line AB in FIG. 1 and shows a state when a voltage is applied.
  • FIG. 2 is a schematic cross-sectional view taken along the line AB in FIG. 1 and shows a state when no voltage is applied.
  • the graph which shows the relationship between the specific resistance ((rho)) of the liquid crystal layer of the liquid crystal display produced using the liquid crystal material A, and the liquid crystal display produced using the liquid crystal material B, and the ultraviolet irradiation amount (UV irradiation amount). It is.
  • FIG. 6 is a graph showing the relationship between the specific resistance ( ⁇ ) of the liquid crystal layer and the residual DC voltage (r ⁇ DC) in a liquid crystal display manufactured using the liquid crystal material A and a liquid crystal display manufactured using the liquid crystal material B. is there.
  • 6 is a schematic cross-sectional view of a liquid crystal display according to Embodiment 2.
  • FIG. 6 is a schematic plan view of a liquid crystal display according to Embodiment 2.
  • FIG. It is a cross-sectional schematic diagram of the liquid crystal display during ultraviolet irradiation in the liquid crystal dropping method. It is a cross-sectional schematic diagram of the liquid crystal display after ultraviolet irradiation in the liquid crystal dropping method.
  • 2 is a schematic cross-sectional view of a liquid crystal display described in Patent Document 1.
  • the liquid crystal display according to this embodiment applies an electric field (lateral electric field) in the substrate surface direction (direction parallel to the substrate surface) to the liquid crystal layer, and controls the liquid crystal orientation to display an image.
  • the display area (image display area) of the liquid crystal display according to the present embodiment is composed of a plurality of picture elements. A plurality of pixels are provided in a matrix.
  • the display area includes a plurality of pixels and displays an image.
  • the display area is an area including such a light shielding area. is there.
  • the liquid crystal display according to the present embodiment includes a liquid crystal display panel 100.
  • the liquid crystal display panel 100 includes an active matrix substrate 1 that is a pair of substrates arranged opposite to each other, and an opposing substrate. It has a substrate 2 and a liquid crystal layer 30 sandwiched between them.
  • polarizing plates 41 and 51 are provided on the outer main surface of the active matrix substrate 1 and the counter substrate 2 (on the side opposite to the liquid crystal layer 30).
  • the polarizing plates 41 and 51 are arranged in crossed Nicols.
  • the substrates 1 and 2 are bonded together by a sealing member provided so as to surround the display area. Moreover, the board
  • a vertical alignment type liquid crystal layer 30 is formed in the gap between the substrates 1 and 2 as a display medium constituting the optical modulation layer.
  • the liquid crystal display according to the present embodiment includes a pair of polarizing plates 41 and 51 arranged in a crossed Nicols manner and a vertical alignment type liquid crystal layer 30, and thus becomes a normally black mode liquid crystal display.
  • the counter substrate 2 includes a colorless and transparent transparent substrate 21 made of glass, plastic, or the like.
  • a matrix (BM) layer On the main surface on the liquid crystal layer 30 side of the transparent substrate 21, black that shields between pixels.
  • an alignment film 22 provided on the side surface.
  • the BM layer is formed from an opaque metal such as Cr, an opaque organic film such as an acrylic resin containing carbon, and the like, and is formed at the boundary between adjacent picture elements.
  • the color layer is used for color display, and is formed of a light-transmitting organic film such as an acrylic resin containing a pigment, and is mainly formed in the pixel region.
  • the dielectric layer 18 is formed from a thermosetting acrylic resin, a photocurable acrylic resin, or the like.
  • the dielectric layer 18 need not be provided, but is preferably provided from the viewpoint of flattening the irregularities of the BM layer and the color layer itself and preventing impurity elution from the BM layer and the color layer.
  • a second common electrode may be formed on the liquid crystal layer 30 side of the transparent substrate 21 in addition to the common electrode 16 described later.
  • the second common electrode is formed between the transparent substrate 21 and the dielectric layer 18 so as to cover the picture element.
  • the electric field generated between the pixel electrode 15 and the common electrode 16 both formed in a comb-teeth shape in the active matrix substrate 1 and the second common electrode formed so as to cover the picture element in the counter substrate 2 is controlled.
  • an optical film such as a retardation plate may be provided between the transparent substrate 21 and the polarizing plate 51.
  • the liquid crystal display of the present embodiment is a color liquid crystal display (active matrix liquid crystal display for color display) having a color layer on the liquid crystal layer 30 side of the counter substrate 2, and is R (red), G (green). ), B (blue), one pixel is composed of three picture elements that output each color light.
  • the kind and number of the color of the picture element which comprises each pixel are not specifically limited, It can set suitably. That is, in the liquid crystal display of the present embodiment, each pixel may be composed of, for example, three color pixels of cyan, magenta, and yellow, or four or more color pixels (for example, R, G, B, and Yellow).
  • the liquid crystal display of the present embodiment may be a monochrome liquid crystal display. In this case, it is not necessary to form a color layer on the counter substrate 2.
  • the active matrix substrate 1 includes a colorless and transparent transparent substrate 11 made of glass, plastic or the like.
  • a gate bus line 26, a Cs bus line, and a source bus are provided on the main surface of the transparent substrate 11 on the liquid crystal layer 30 side.
  • TFT thin film transistor
  • drain wiring (drain) 25 connected to each TFT 23, and provided separately for each pixel
  • an optical film such as a retardation plate may be provided between the transparent substrate 11 and the polarizing plate 41.
  • the alignment films 12 and 22 provided on the active matrix substrate 1 and the counter substrate 2 are vertical alignment films, and are formed by coating from a general alignment film material such as polyimide.
  • the vertical alignment film is not usually rubbed, but can align liquid crystal compounds (liquid crystal molecules) substantially perpendicular to the film surface when no voltage is applied. Therefore, as shown in FIG. 3, the liquid crystal compound 5 is aligned substantially perpendicular to the surfaces of the substrates 1 and 2 when no voltage is applied.
  • An image signal (video signal) is supplied to the pixel electrode 15 via a TFT 23 from a source bus line 24 extending in the vertical direction between adjacent picture elements.
  • a rectangular wave is applied to the pixel electrode 15 according to the image signal.
  • Each pixel electrode 15 is electrically connected to the drain wiring 25 of the TFT through a contact hole provided in the interlayer insulating film.
  • the common electrode 16 is supplied with a common signal common to the picture elements. Further, the common electrode 16 is connected to a common voltage generation circuit and is set to a predetermined potential (typically 0 V).
  • the source bus line 24 is connected to a source driver (data line driving circuit).
  • a gate bus line 26 connected to a gate driver (scanning line driving circuit) extends in the left-right direction between adjacent picture elements.
  • the gate bus line 26 also functions as a gate of the TFT 23, and a scanning signal supplied in a pulse manner from the gate driver to the gate bus line 26 at a predetermined timing is applied to each TFT 23 in a line sequential manner.
  • An image signal supplied from the source bus line 24 is applied at a predetermined timing to the pixel electrode 15 connected to the TFT 23 which is turned on for a certain period by the input of the scanning signal.
  • the image signal of a predetermined level written in the liquid crystal layer 30 is held for a certain period between the pixel electrode 15 to which the image signal is applied and the common electrode 16.
  • a storage capacitor is formed in parallel with the liquid crystal capacitor formed between the pixel electrode 15 and the common electrode 16.
  • the storage capacitor is formed between the drain wiring 24 of the TFT 23 and the Cs bus line provided in parallel with the gate bus line 26. Note that the Cs bus line is also connected to the common voltage generation circuit in the same manner as the common electrode 16.
  • the pixel electrode 15 is formed of a transparent conductive film such as ITO, a metal film such as aluminum or chromium, and the like.
  • the shape of the pixel electrode 15 when the liquid crystal display panel 100 is viewed from above is a comb-like shape.
  • the common electrode 16 is also formed of a transparent conductive film such as ITO, a metal film such as aluminum, and the like, and the shape of the common electrode 16 when the liquid crystal display panel 100 is viewed in plan is a comb-like shape.
  • the pixel electrodes 15 and the common electrodes 16 are alternately arranged with a constant interval.
  • the comb-like pixel electrode 15 and the comb-like common electrode 16 are arranged to face each other in a direction in which the comb teeth mesh with each other.
  • the width (minimum width) of the pixel electrode 15 and the common electrode 16 is, for example, 2 to 5 ⁇ m (preferably 2 to 3 ⁇ m). If it exceeds 5 ⁇ m, the aperture ratio decreases and the transmittance decreases. Moreover, there exists a possibility that yields, such as a disconnection, may fall that it is less than 2 micrometers.
  • each picture element includes a plurality of regions having different intervals between the pixel electrode 15 and the common electrode 16 (hereinafter also simply referred to as electrode intervals). That is, in each picture element, a region having a relatively narrow electrode interval (region of Sn) and a region having a relatively large electrode interval (region of Sw) may be formed.
  • the threshold value of the VT characteristic in each region can be made different, the slope of the VT characteristic (VT curve) of the entire picture element particularly at a low gradation can be made gentle.
  • the occurrence of whitening can be suppressed and the viewing angle characteristics can be improved.
  • White floating is a phenomenon in which a display that should appear dark appears to be whitish when the viewing direction is tilted obliquely from the front in a state where a relatively dark display with low gradation is performed.
  • the liquid crystal display of this embodiment applies an image signal (voltage) to the pixel electrode 15 via the TFT 23, so that the surface of the substrate (the active matrix substrate 1 and the counter substrate 2) is between the pixel electrode 15 and the common electrode 16.
  • An electric field (lateral electric field) in a direction (horizontal direction, a direction parallel to the substrate surface) is generated. Then, the liquid crystal is driven by this electric field, and an image is displayed by changing the transmittance of each picture element.
  • the liquid crystal display of this embodiment forms a distribution of electric field strength in the liquid crystal layer 30 by applying an electric field. This causes distortion of the alignment of the liquid crystal compound. Then, the retardation of the liquid crystal layer 30 is changed using the distortion. More specifically, the initial alignment state of the liquid crystal layer 30 is vertical alignment.
  • a voltage is applied between the comb-like pixel electrode 15 and the common electrode 16, a parabolic electric field is formed between the electrodes 15 and 16.
  • This electric field is generally called a horizontal electric field because it becomes an electric field (horizontal electric field) substantially horizontal to the main surfaces of the substrates 1 and 2 in the light transmission region of the liquid crystal layer 30.
  • the liquid crystal compounds are arranged in a bow shape (bend orientation), and two domains whose director directions are 180 ° different from each other are formed between the electrodes 15 and 16 as shown in FIG.
  • the liquid crystal compound In the region where the two domains are adjacent (usually on the center line of the gap between the pixel electrode 15 and the common electrode 16), the liquid crystal compound is always aligned vertically regardless of the applied voltage value. Therefore, a dark line (dark line) is always generated in this region (boundary) regardless of the applied voltage value. In addition, a horizontal electric field is not generated on the pixel electrode 15 and the common electrode 16, and the liquid crystal compound remains vertically aligned, and a dark line is always generated on the pixel electrode 15 and the common electrode 16.
  • an ultraviolet curable sealant is applied to either the active matrix substrate 1 or the counter substrate 2 so as to surround the display region, thereby forming a rectangular frame-shaped seal pattern.
  • An injection port for injecting the liquid crystal material is not formed in the seal pattern.
  • the ultraviolet curable sealing material has a property of being cured by ultraviolet rays (ultraviolet curable).
  • the ultraviolet curable sealant may have a property of being cured by heating (thermosetting) in addition to the ultraviolet curable property.
  • fine droplets of the liquid crystal material are dropped and applied onto the entire surface of the active matrix substrate 1 or the counter substrate 2 on which the seal pattern is formed, with the UV curable sealing material being uncured, and then the other substrate is overlaid.
  • UV irradiation is performed with an energy of, for example, about 10 to 15 J to cure the seal pattern and simultaneously form the liquid crystal layer 30 with a desired cell thickness.
  • the liquid crystal material is sealed in a region between the substrates 1 and 2 and surrounded by the seal member.
  • the sealing member does not have a liquid crystal inlet sealing member.
  • the sealing member is a cured product of the sealing material, and the liquid crystal inlet sealing member is a member for sealing the inlet.
  • the liquid crystal material may be dropped and applied to the active matrix substrate 1 or the counter substrate 2 on which no seal pattern is formed. In this case, the liquid crystal material is dropped into a region corresponding to the region surrounded by the seal pattern.
  • the specific resistance of the liquid crystal layer 30 is 1.5 ⁇ 10 14 ⁇ ⁇ cm or more, and since the amount of impurity ions in the liquid crystal layer is small, occurrence of flicker and image sticking can be suppressed.
  • the upper limit of the specific resistance of the liquid crystal layer 30 is preferably as high as possible from the viewpoint of reducing the amount of impurity ions in the liquid crystal layer 30, but the characteristics of the liquid crystal material and the characteristics of the alignment films 12 and 22 are considered. Then, the upper limit value of the specific resistance of the liquid crystal layer 30 is preferably set to about 1.0 ⁇ 10 15 ⁇ ⁇ cm. The reason will be described below.
  • the magnitude of the residual DC voltage varies depending not only on the amount of impurity ions in the liquid crystal layer but also on the combination of the liquid crystal material and the alignment film.
  • the dielectric constant of the alignment film and the specific resistance of the alignment film If the product and the product of the dielectric constant of the liquid crystal material and the specific resistance of the liquid crystal material are the same, the residual DC component resulting from the combination will not occur.
  • the dielectric constant of a general alignment film is approximately the same as the dielectric constant of all liquid crystal materials including the liquid crystal material used in this embodiment, and the specific resistance of the general alignment film is approximately 1.0 ⁇ 10 10. It falls within the range of 15 ⁇ ⁇ cm or less.
  • the specific resistance of the liquid crystal layer 30 is 1.0 ⁇ 10 15 ⁇ ⁇ cm or less from the viewpoint of more effectively suppressing the occurrence of flicker and image sticking. Is preferred.
  • the specific resistance of the liquid crystal layer 30 may be 5.0 ⁇ 10 14 ⁇ ⁇ cm or less, or 3.0 ⁇ 10 14 ⁇ ⁇ cm or less.
  • the liquid crystal material (liquid crystal composition) of the liquid crystal layer 30 has a phenyl-bicyclohexane-based, phenyl-biphenyl-based, bicyclohexane-based, or terphenyl-based structure in the core, and an alkyl group or an alkoxy group at the terminal or in the middle. And having a refractive index anisotropy.
  • the liquid crystal material includes a liquid crystal compound having a polar group such as a fluoro group at the terminal or in the middle, and has positive dielectric anisotropy. Further, the liquid crystal material includes a liquid crystal compound having a viscosity reducing effect for decreasing the viscosity.
  • the above liquid crystal compound preferably has light resistance. Thereby, even if intense ultraviolet rays are irradiated, generation of impurity ions can be effectively suppressed.
  • the dielectric anisotropy ⁇ of the liquid crystal layer 30 is not particularly limited, but is preferably a large value, specifically, 15 to 25 (preferably 18 to 22) at 25 ° C. If it exceeds 25, it becomes difficult to maintain the desired liquid crystal phase and the viscosity becomes high, resulting in a slow response speed. If it is less than 15, the VT (voltage-transmittance) characteristics shift to the high voltage side and transmit. The rate will drop.
  • the liquid crystal layer 30 preferably has a specific resistance change rate of 32% or less before and after ultraviolet irradiation, and the smaller the specific resistance change rate, the more preferable.
  • the small rate of change in specific resistance before and after UV irradiation means that the amount of impurity ions generated by UV irradiation is small, and it is possible to more effectively suppress deterioration in display quality such as image sticking and flicker. it can. From such a viewpoint, the lower limit of the rate of change in specific resistance is not particularly limited.
  • the liquid crystal compound 5 in the liquid crystal layer 30 is homeotropic when no voltage is applied (when an electric field is not generated by the electrodes 15 and 16) due to the alignment regulating force of the alignment films 12 and 22. Indicates orientation.
  • the pretilt angle of the liquid crystal layer 30 is 86 ° or more (preferably 88 ° or more) and 90 ° or less. If the angle is less than 86 °, the front contrast is significantly reduced.
  • the liquid crystal display according to Embodiment 1 was produced, and the specific resistance and residual DC voltage of the liquid crystal layer were measured.
  • the specific resistance of the liquid crystal layer was measured using a TFT liquid crystal panel evaluation apparatus LCM-3 type (manufactured by Toyo Technica Co., Ltd.). This apparatus can measure specific resistance in a state of a liquid crystal layer, that is, in a state where a liquid crystal material is sandwiched between substrates. Under a temperature condition of 70 ° C., a resistance value was measured by applying a triangular wave voltage of 0.01 V of 0V-10V to the liquid crystal display panel, and a specific resistance was calculated from resistance value ⁇ electrode area / electrode interval.
  • the residual DC voltage was determined by the flicker elimination method [Operation I] described in WO2007 / 141935. Specifically, a DC offset voltage is applied to the liquid crystal cell at 2 V for 2 hours, and then the liquid crystal cell is driven with a rectangular wave voltage (V 15% , 30 Hz) to apply a DC offset voltage to be applied so that flicker is not observed. The DC offset voltage was adjusted to be the residual DC voltage. In addition, the measurement was performed in 25 degreeC, and the self-made apparatus comprised including the generator, the photomultiplier, the oscilloscope, and the computer which controls these was used. It is considered that the residual DC voltage increases as the amount of impurity ions in the liquid crystal layer increases. That is, the higher the residual DC voltage, the more easily the deterioration of display quality is observed.
  • a plurality of liquid crystal displays were manufactured using a liquid crystal material A having a dielectric anisotropy ⁇ of 16 and an initial specific resistance of 2.42 ⁇ 10 14 ⁇ ⁇ cm as a liquid crystal material forming a liquid crystal layer.
  • These liquid crystal displays were manufactured by a liquid crystal dropping method (ODF) with a seal pattern formed by an ultraviolet curable sealing material.
  • ODF liquid crystal dropping method
  • the sealing material and the liquid crystal layer were irradiated with ultraviolet rays.
  • the specific resistance of the liquid crystal layer decreases with the irradiation amount of ultraviolet light, and the specific resistance of the liquid crystal layer is 1.67 ⁇ 10 14 ⁇ ⁇ cm when irradiated with ultraviolet light having an energy of 12 J.
  • the specific resistance of the layer was 4.10 ⁇ 10 13 ⁇ ⁇ cm.
  • the specific resistance change rate before and after UV irradiation was 31.1% for 12J irradiation and 83% for 60J irradiation, respectively.
  • the above-mentioned liquid crystal display produced by using the liquid crystal material A and irradiating the sealing material and the liquid crystal layer with ultraviolet rays having 12 J energy is referred to as the liquid crystal display A after being irradiated with 12 J ultraviolet rays.
  • the liquid crystal display produced by irradiating the material and the liquid crystal layer with ultraviolet rays having energy of 60 J is referred to as a liquid crystal display A after irradiation with ultraviolet rays of 60 J.
  • the initial specific resistance of the liquid crystal material A was measured with a liquid crystal display produced by irradiating only the sealing material with ultraviolet rays.
  • the liquid crystal display manufactured by using the liquid crystal material A and irradiating only the sealing material with ultraviolet rays is referred to as the liquid crystal display A before the ultraviolet irradiation.
  • the liquid crystal display A before ultraviolet irradiation and the liquid crystal display A after 12J ultraviolet irradiation correspond to the liquid crystal display of Embodiment 1 according to the present invention, and the liquid crystal display A after 60 J ultraviolet irradiation is This corresponds to a comparative liquid crystal display.
  • the residual DC voltage in each liquid crystal display A was measured before ultraviolet irradiation, after 12 J ultraviolet irradiation, and after 60 J ultraviolet irradiation.
  • the residual DC voltage of the liquid crystal display A before the ultraviolet irradiation was 130 mV
  • the residual DC voltage of the liquid crystal display A after the ultraviolet irradiation of 12 J was 180 mV
  • the residual DC voltage of the liquid crystal display A after the ultraviolet irradiation of 60 J was 780 mV. .
  • a plurality of liquid crystal displays are manufactured by using a liquid crystal material B having a dielectric anisotropy ⁇ of 18 and an initial specific resistance of 2.45 ⁇ 10 14 ⁇ ⁇ cm as a liquid crystal material forming a liquid crystal layer. did.
  • the liquid crystal material B has an initial specific resistance that is substantially the same as that of the liquid crystal material A, but is a liquid crystal material that is more likely to generate impurity ions when irradiated with ultraviolet light than the liquid crystal material A.
  • the liquid crystal display produced using the liquid crystal material B is the same as the liquid crystal display produced using the liquid crystal material A, except that the liquid crystal material B is used instead of the liquid crystal material A.
  • the specific resistance of the liquid crystal layer was decreased with the amount of ultraviolet irradiation to the sealing material and the liquid crystal layer, and the specific resistance of the liquid crystal layer was decreased to 5.29 ⁇ 10 13 ⁇ ⁇ cm by ultraviolet irradiation with 12 J energy.
  • the liquid crystal display produced by using the liquid crystal material B and irradiating the sealing material and the liquid crystal layer with ultraviolet rays having 12 J energy will be referred to as the liquid crystal display B after the ultraviolet irradiation with 12 J.
  • the initial specific resistance of the liquid crystal material B was measured by a liquid crystal display produced by irradiating only the sealing material with ultraviolet rays.
  • the liquid crystal display produced by using the liquid crystal material B and irradiating only the sealing material with ultraviolet rays will be referred to as the liquid crystal display B before ultraviolet irradiation.
  • the liquid crystal display B before the ultraviolet irradiation corresponds to the liquid crystal display of Embodiment 1 according to the present invention
  • the liquid crystal display B after the 12J ultraviolet irradiation corresponds to the liquid crystal display of the comparative form.
  • the residual DC voltage in each liquid crystal display B before ultraviolet irradiation and after 12J ultraviolet irradiation was measured.
  • the residual DC voltage of the liquid crystal display before UV irradiation was 200 mV
  • the residual DC voltage of the liquid crystal display after UV irradiation of 12 J was 680 mV.
  • Table 1 shows the specific resistance and residual DC voltage of the liquid crystal layer in each liquid crystal display using the liquid crystal materials A and B.
  • FIG. 4 shows the relationship between the specific resistance ( ⁇ ) of the liquid crystal layer of the liquid crystal display manufactured using the liquid crystal material A and the liquid crystal display manufactured using the liquid crystal material B and the irradiation amount of ultraviolet rays (UV irradiation amount). It is a graph which shows a relationship. As shown in FIG. 4, the specific resistance of the liquid crystal layer decreased as the amount of ultraviolet irradiation increased.
  • FIG. 5 shows the relationship between the specific resistance ( ⁇ ) of the liquid crystal layer and the residual DC voltage (r ⁇ DC) in the liquid crystal display manufactured using the liquid crystal material A and the liquid crystal display manufactured using the liquid crystal material B. It is a graph which shows.
  • the residual DC voltages of the liquid crystal display A before ultraviolet irradiation, the liquid crystal display A after 12J ultraviolet irradiation, and the liquid crystal display B before ultraviolet irradiation are 130 mV, 180 mV, and 200 mV, respectively, and display quality such as flicker and burn-in A decrease in was not observed.
  • the liquid crystal display A after UV irradiation of 60J and the liquid crystal display B after UV irradiation of 12J are large in residual DC voltages of 780 mV and 680 mV, respectively, and it is considered that a large amount of impurity ions were generated by the UV irradiation. In all cases, a decrease in display quality such as flicker and burn-in was observed. Therefore, when the residual DC voltage is 200 mV or less, that is, as shown in FIG. 5, when the specific resistance of the liquid crystal layer is 1.5 ⁇ 10 14 ⁇ ⁇ cm or more, the display quality is kept good.
  • the liquid crystal display of the second embodiment is different from the first embodiment in the following points. That is, the liquid crystal display panel 200 of Embodiment 2 has a counter electrode (second common electrode) on the counter substrate 2 side. Specifically, as illustrated in FIG. 6, the counter electrode 17, the dielectric layer 18, and the alignment film 22 are stacked in this order on the main surface of the transparent substrate 21 on the liquid crystal layer 30 side. Note that a color layer and / or a BM layer may be provided between the counter electrode 17 and the transparent substrate 21.
  • the counter electrode 17 is formed of a transparent conductive film such as ITO or IZO. As shown in FIG. 7, the counter electrode 17 is formed without a break so as to cover at least the entire display region 6. A predetermined potential common to each pixel (or picture element) is applied to the counter electrode 17. In the frame region of the liquid crystal display panel 200, as with the liquid crystal display panel 100, a seal member 7 that does not have a liquid crystal inlet sealing member is provided.
  • the dielectric layer 18 is formed from a transparent insulating material. Specifically, it is formed from an inorganic insulating film such as silicon nitride, an organic insulating film such as acrylic resin, or the like. The dielectric layer 18 is formed without a break so as to cover at least the entire display region 6.
  • the transparent substrate 11 is provided with a pair of comb-like electrodes including the pixel electrode 15 and the common electrode 16 as in the first embodiment, and is further provided with an alignment film 12. Further, polarizing plates 41 and 51 are disposed on the outer main surfaces of the two transparent substrates 11 and 21 (on the side opposite to the liquid crystal layer 30).
  • the voltage applied to the pixel electrode 15 is different from both the voltage applied to the common electrode 16 and the voltage applied to the counter electrode 17 except during black display.
  • an oblique electric field (an oblique electric field with respect to the main surfaces of the substrates 1 and 2) is formed from the pixel electrode 15 toward the counter electrode 17. Further, a horizontal electric field (electric field substantially parallel to the main surfaces of the substrates 1 and 2) is formed from the pixel electrode 15 toward the common electrode 16. This transverse electric field serves to help form an oblique electric field. Therefore, due to the presence of the lateral electric field, the oblique electric field does not become so weak even if it is separated from the pixel electrode 15. Therefore, the liquid crystal compound that has been vertically aligned when no voltage is applied is aligned parallel to the oblique electric field when the voltage is applied.
  • liquid crystal display of this embodiment flicker and image sticking can be suppressed as in the first embodiment. Further, the response speed can be improved by forming the counter electrode 17.
  • the counter electrode 17 when the counter electrode 17 is adjacent to the alignment film 22, equipotential lines are concentrated near the interface between the counter substrate 2 and the liquid crystal layer 30. For this reason, the component in the normal direction of the oblique electric field becomes strong in the liquid crystal layer 30, and the liquid crystal compound may not fall sufficiently sideways.
  • the dielectric layer 18 is provided on the liquid crystal layer 30 side of the counter electrode 17. Therefore, concentration of equipotential lines near the interface between the counter substrate 2 and the liquid crystal layer 30 can be suppressed. Therefore, the component in the normal direction of the oblique electric field in the liquid crystal layer 30 can be weakened. As a result, the liquid crystal compound can be tilted sideways sufficiently, and the transmittance of the entire picture element can be improved.
  • common electrode 16 and the counter electrode 17 may be grounded, and voltages having the same magnitude and the same polarity may be applied to the common electrode 16 and the counter electrode 17.
  • the number of regions having different electrode intervals in one picture element is not particularly limited, and may be three or more. Even when there are three or more, the occurrence of whitening can be suppressed and the viewing angle characteristics can be improved in the same manner as in the case of two.

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Liquid Crystal (AREA)
  • Geometry (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)

Abstract

La présente invention porte sur un dispositif d'affichage à cristaux liquides, dans lequel dispositif une défaillance d'affichage tel qu'un papillotement ou une image rémanente ne se produit pas facilement. Ce dispositif d'affichage à cristaux liquides comporte : une paire de substrats (1, 2) et une couche de cristaux liquides (30) qui est prise en sandwich entre la paire de substrats ; un composé de cristaux liquides (5) contenu dans la couche de cristaux liquides étant aligné sensiblement perpendiculairement aux surfaces de la paire de substrats lorsqu'aucune tension n'est appliquée à ceux-ci. L'un de la paire de substrats, le substrat (1), a une paire d'électrodes (15, 16), et l'alignement du composé de cristaux liquides (5) est commandé par le champ électrique généré par la paire d'électrodes. La couche de cristaux liquides (30) présente une anisotropie diélectrique positive, et la couche de cristaux liquides (30) présente une résistance spécifique de 1,5 × 1014 Ω·cm ou plus.
PCT/JP2012/054747 2011-02-28 2012-02-27 Dispositif d'affichage à cristaux liquides WO2012118006A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2011041556 2011-02-28
JP2011-041556 2011-02-28

Publications (1)

Publication Number Publication Date
WO2012118006A1 true WO2012118006A1 (fr) 2012-09-07

Family

ID=46757940

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2012/054747 WO2012118006A1 (fr) 2011-02-28 2012-02-27 Dispositif d'affichage à cristaux liquides

Country Status (1)

Country Link
WO (1) WO2012118006A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018087976A (ja) * 2016-11-22 2018-06-07 株式会社半導体エネルギー研究所 表示装置およびその作製方法、ならびに電子機器

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003005187A (ja) * 2001-04-06 2003-01-08 Toray Ind Inc 液晶表示装置
WO2010137386A1 (fr) * 2009-05-27 2010-12-02 シャープ株式会社 Dispositif d'affichage à cristaux liquides

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003005187A (ja) * 2001-04-06 2003-01-08 Toray Ind Inc 液晶表示装置
WO2010137386A1 (fr) * 2009-05-27 2010-12-02 シャープ株式会社 Dispositif d'affichage à cristaux liquides

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018087976A (ja) * 2016-11-22 2018-06-07 株式会社半導体エネルギー研究所 表示装置およびその作製方法、ならびに電子機器
US11532650B2 (en) 2016-11-22 2022-12-20 Semiconductor Energy Laboratory Co., Ltd. Display device, method for manufacturing the same, and electronic device

Similar Documents

Publication Publication Date Title
JP4394479B2 (ja) 液晶表示装置及びその製造方法
US6424393B1 (en) Liquid crystal display apparatus
JP3879463B2 (ja) 液晶表示パネル，液晶表示装置、及び液晶テレビ
EP2345927A1 (fr) Dispositif d'affichage à cristaux liquides
US8339556B2 (en) Electro-optical device and display device with interdigital electrode portions on at least first and second substrates which are non-overlapping in a direction normal to the substrates
WO2010137427A1 (fr) Dispositif d'affichage à cristaux liquides
WO2011040080A1 (fr) Dispositif d'affichage à cristaux liquides
WO2007040158A1 (fr) Dispositif d’affichage à cristaux liquides et récepteur de télévision
RU2509326C1 (ru) Жидкокристаллическое устройство отображения
WO2010041491A1 (fr) Afficheur à cristaux liquides (lcd)
WO2010137428A1 (fr) Dispositif d'affichage à cristaux liquides
US20090201453A1 (en) Liquid crystal display panel and method of manufacturing the same
JP5323276B2 (ja) 液晶表示装置およびその製造方法
US20130271680A1 (en) Liquid crystal panel, and liquid crystal display
US9841643B2 (en) Liquid crystal display apparatus
WO2011083616A1 (fr) Afficheur a cristaux liquides
WO2012118006A1 (fr) Dispositif d'affichage à cristaux liquides
US20120127416A1 (en) Liquid crystal display device
KR20120133927A (ko) 표시 장치 및 표시 장치 제조 방법
JP4328281B2 (ja) 液晶表示装置
JP2006301466A (ja) 液晶表示装置
JP4519691B2 (ja) 液晶表示パネル及びそれを備えた液晶表示装置
JP5592979B2 (ja) 液晶表示装置およびその製造方法
JP5159687B2 (ja) 液晶表示装置
JP7398926B2 (ja) 液晶表示装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12752603

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12752603

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP