JP2010286817A - Liquid crystal panel, and defect correction method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defect correction method for a liquid crystal panel, the method correcting a defect. <P>SOLUTION: The defect correction method for the liquid crystal panel includes: a step of preparing the liquid crystal panel 100 provided with a TFT substrate 120 having a pixel electrode 124 and the first alignment layer 126, an counter substrate 140 having a counter electrode 142 and the first alignment layer 144, and a mixture C interposed between the TFT substrate 120 and the counter substrate 140, and containing a liquid crystal compound and a photopolymerizable compound; a step of specifying a normal area and a defective area in the liquid crystal panel 100; and a step of irradiating the defective area in the liquid crystal panel 100, with an ultraviolet ray, so as not to irradiate the normal area in the liquid crystal panel 100, with the ultraviolet ray. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid crystal panel and a defect correcting method thereof.

  The liquid crystal panel is used not only as a large television but also as a small display device such as a display unit of a mobile phone. Conventionally used TN (Twisted Nematic) mode liquid crystal panels have a relatively narrow viewing angle. However, in recent years, wide viewing angles such as IPS (In-Plane-Switching) mode and VA (Vertical Alignment) mode have been used. A liquid crystal panel has been produced. Among such wide viewing angle modes, the VA mode can be used in many liquid crystal panels because it can achieve a high contrast ratio.

  As one type of VA mode, an MVA (Multi-domain Vertical Alignment) mode in which a plurality of liquid crystal domains are formed in one pixel region is known. In an MVA mode liquid crystal panel, an alignment regulating structure is provided on at least one liquid crystal layer side of a pair of substrates facing each other with a vertical alignment type liquid crystal layer interposed therebetween. The alignment regulating structure is, for example, a linear slit (opening) or a rib (projection structure) provided on the electrode. With the alignment control structure, alignment control force is applied from one or both sides of the liquid crystal layer, and a plurality of liquid crystal domains (typically four liquid crystal domains) having different alignment directions are formed, thereby improving viewing angle characteristics. Yes.

  As one type of VA mode, a CPA (Continuous Pinwheel Alignment) mode is also known. In a general CPA mode liquid crystal panel, a pixel electrode having a highly symmetric shape is provided, and a protrusion is provided on the counter electrode corresponding to the center of the liquid crystal domain. This protrusion is also called a rivet. When a voltage is applied, the liquid crystal molecules are inclined and aligned in a radial shape in accordance with an oblique electric field formed by the counter electrode and the highly symmetrical pixel electrode. In addition, the tilt alignment of the liquid crystal molecules is stabilized by the alignment regulating force on the tilted side surface of the rivet. Thus, viewing angle characteristics are improved by aligning liquid crystal molecules in one pixel in a radial shape.

  In a general VA mode, liquid crystal molecules are aligned in the normal direction of the main surface of the alignment film when no voltage is applied. When a voltage is applied to the liquid crystal layer, the liquid crystal molecules are aligned in a predetermined direction. On the other hand, in order to improve the response speed of a liquid crystal panel, use of Polymer Sustained Alignment Technology (hereinafter referred to as “PSA technology”) has been studied (for example, see Patent Documents 1 and 2). In the PSA technology, a small amount of a photopolymerizable compound (for example, a photopolymerizable monomer) is mixed in a mixture, the mixture is applied between the TFT substrate and the counter substrate, and then between the pixel electrode and the counter electrode. This is a technique for forming a polymer by irradiating a photopolymerizable compound with ultraviolet light while a voltage is applied. When the PSA technique is used, the alignment state of the liquid crystal molecules when the polymer is generated is maintained (stored), so that the pretilt direction of the liquid crystal molecules can be controlled.

  The liquid crystal display device of Patent Document 1 is an MVA mode in which slits or ribs are provided as an alignment regulating structure. In the liquid crystal display device of Patent Document 1, linear slits and / or ribs are provided, and the liquid crystal molecules are aligned so that the azimuth component of the liquid crystal molecules is orthogonal to the slits or ribs when a voltage is applied. . When ultraviolet light is irradiated in this state, a polymer is formed and the alignment state of the liquid crystal molecules is maintained (stored). Thereafter, even when the voltage application is finished, the liquid crystal molecules are inclined in the pretilt direction from the normal direction of the main surface of the alignment film.

  Further, the liquid crystal display device of Patent Document 2 has fine stripe-patterned electrodes, and when a voltage is applied to the liquid crystal layer, the liquid crystal molecules are aligned parallel to the longitudinal direction of the stripe-shaped pattern. This is in contrast to the liquid crystal display device of Patent Document 1, in which the azimuth angle component of the liquid crystal molecules is orthogonal to the slits or ribs. In addition, since the plurality of slits are provided, disorder of orientation is suppressed. In this state, ultraviolet light is irradiated to maintain (store) the alignment state of the liquid crystal molecules. Thereafter, even when the voltage application is finished, the liquid crystal molecules are inclined in the pretilt direction from the normal direction of the main surface of the alignment film. In this way, pretilt is imparted to the liquid crystal molecules in the state where no voltage is applied, thereby improving the response speed.

  As another method for improving the response speed of a liquid crystal panel, it is known to use a photo-alignment film (see, for example, Patent Document 3). By irradiating the alignment film containing polyimide with ultraviolet light, a photo-alignment film that defines the pretilt direction of liquid crystal molecules can be formed, thereby improving the response speed. The liquid crystal display device thus manufactured is also called a VATN mode.

JP 2002-357830 A JP 2003-149647 A Special table 2008-538819

  Generally, after manufacturing a liquid crystal panel, a defect inspection is performed. If a defect occurs in the LCD panel, the display quality and thus the yield may decrease. However, if the defect in the LCD panel can be corrected, the LCD panel will operate normally and suppress a decrease in display quality and yield. it can.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a simple defect correction method for a liquid crystal panel, and a liquid crystal panel in which a reduction in display quality and yield is suppressed.

  A defect correction method for a liquid crystal panel according to the present invention is provided between a TFT substrate having a pixel electrode and a first alignment film, a counter substrate having a counter electrode and a second alignment film, and the TFT substrate and the counter substrate. Preparing a liquid crystal panel comprising a liquid crystal compound and a mixture containing a photopolymerizable compound, identifying a normal region and a defective region of the liquid crystal panel, and irradiating the normal region of the liquid crystal panel with ultraviolet light Irradiating the defect area of the liquid crystal panel with ultraviolet light.

  In one embodiment, the defect correcting method irradiates the entire surface of the liquid crystal panel with ultraviolet light in a state where a voltage is applied between the pixel electrode and the counter electrode before specifying the defective area of the liquid crystal panel. This further includes a step of forming an alignment sustaining layer on the mixture side of each of the first alignment film and the second alignment film.

  In one embodiment, the defect correcting method includes a step of irradiating the entire surface of the liquid crystal panel with ultraviolet light without applying a voltage between the pixel electrode and the counter electrode after forming the alignment maintaining layer. In addition.

  In one embodiment, the step of irradiating the ultraviolet light without applying a voltage between the pixel electrode and the counter electrode is performed after a defective region of the liquid crystal panel is specified.

  In one embodiment, the defect region of the liquid crystal panel is specified after the irradiation with the ultraviolet light without applying a voltage between the pixel electrode and the counter electrode.

  In one embodiment, the defect correction method further includes a step of preparing a mask having a light shielding region and a light transmission region before the step of irradiating the defect region with the ultraviolet light, and the defect region includes the ultraviolet region. The step of irradiating light is performed on the liquid crystal panel such that the light shielding area of the mask corresponds to the normal area of the liquid crystal panel and the light transmission area of the mask corresponds to the defective area of the liquid crystal panel. And arranging the mask.

  In one embodiment, the step of irradiating the defect region with the ultraviolet light includes a step of adjusting the ultraviolet light so as to correspond to the defect region of the liquid crystal panel.

  In one embodiment, the step of preparing the liquid crystal panel includes a step of performing a photo-alignment process on at least one of the first alignment film and the second alignment film.

  The liquid crystal panel according to the present invention is a liquid crystal panel provided with a plurality of pixels including a first pixel and a second pixel, wherein the first pixel electrode defining the first pixel and the second pixel defining the second pixel. A plurality of pixel electrodes including a pixel electrode, a plurality of thin film transistors including a first thin film transistor corresponding to the first pixel electrode and a second thin film transistor corresponding to the second pixel electrode, and a TFT substrate having a first alignment film; A counter substrate having a counter electrode and a second alignment film, a liquid crystal layer sandwiched between the first alignment film and the second alignment film, and the liquid crystal layer side of each of the first alignment film and the second alignment film The voltage-current characteristic of the first thin film transistor is different from the voltage-current characteristic of the second thin film transistor, and the voltage-current characteristic of the first pixel is different from the voltage-current characteristic of the first pixel. Over rate characteristic voltage of the second pixel - substantially equal to the transmittance characteristics.

  In one embodiment, at least one of the first alignment film and the second alignment film is a photo-alignment film.

  According to the present invention, defect correction of a liquid crystal panel can be easily performed. In addition, according to the present invention, it is possible to suppress a decrease in display quality and yield of the liquid crystal panel.

(A) is a schematic diagram of 1st Embodiment of the liquid crystal panel by this invention, (b) is a typical top view of the TFT substrate in the liquid crystal panel shown to (a). (A)-(e) is a schematic diagram for demonstrating manufacture and defect correction of the liquid crystal panel shown in FIG. (A) is a graph showing voltage-current characteristics of different TFTs in the liquid crystal panel shown in FIG. 1, (b) is a graph showing voltage-transmittance characteristics of different pixels before defect correction, and (c). FIG. 4 is a graph showing voltage-transmittance characteristics of different pixels after defect correction. It is a schematic diagram of the defect detection and correction apparatus suitable for the defect correction shown in FIG. It is a schematic diagram of 2nd Embodiment of the liquid crystal panel by this invention. (A) And (b) is a schematic diagram for demonstrating the defect correction of the liquid crystal panel shown in FIG. It is a schematic diagram of another embodiment of the liquid crystal panel by this invention. (A) And (b) is a schematic diagram of the alignment film in the liquid crystal panel shown in FIG. 7, (c) is a schematic diagram which shows the orientation direction of the liquid crystal molecule | numerator of the center of a liquid crystal domain. (A) And (b) is a schematic diagram for demonstrating the defect correction of the liquid crystal panel shown in FIG.

  Hereinafter, an embodiment of a liquid crystal panel according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

(Embodiment 1)
Hereinafter, a first embodiment of a liquid crystal panel according to the present invention will be described with reference to FIG. FIG. 1A shows a schematic diagram of a liquid crystal panel 100 of the present embodiment. The liquid crystal panel 100 includes a TFT substrate 120 having a pixel electrode 124 and an alignment film 126, a counter substrate 140 having a counter electrode 144 and an alignment film 146, and a liquid crystal layer 160 provided between the TFT substrate 120 and the counter substrate 140. And.

  The pixel electrode 124 and the alignment film 126 of the TFT substrate 120 are provided on the insulating substrate 122, and the alignment film 126 covers the pixel electrode 124. Although not shown in FIG. 1A, a thin film transistor (TFT) and wiring connected to the thin film transistor (TFT) are provided between the insulating substrate 122 and the pixel electrode 124.

  The counter electrode 144 and the second alignment film 146 of the counter substrate 140 are provided on the insulating substrate 142, and the alignment film 146 covers the counter electrode 144. For example, the insulating substrates 122 and 142 are transparent glass substrates. Note that the counter substrate 140 may be provided with a color filter layer as necessary, and the counter substrate 140 provided with the color filter layer is also called a color filter substrate. In the following description of this specification, the alignment films 126 and 146 may be referred to as a first alignment film 126 and a second alignment film 146, respectively, and the insulating substrates 122 and 142 may be referred to as a first insulating substrate 122 and a second alignment film, respectively. Sometimes referred to as an insulating substrate 142.

  The alignment films 126 and 146 are all vertical alignment films, and the liquid crystal layer 160 is a vertical alignment type. The liquid crystal layer 160 contains a nematic mixture (liquid crystal molecules 162) having negative dielectric anisotropy, and the liquid crystal molecules 162 are substantially perpendicular to the main surfaces of the alignment film 126 and the alignment film 146 when no voltage is applied. Orient.

  In the liquid crystal panel 100, each of the matrix-shaped pixels along the plurality of rows and the plurality of columns is defined by the pixel electrode 124. In this specification, “pixel” refers to the smallest unit that expresses a specific gradation in display, and corresponds to a unit that expresses each gradation of red, green, and blue in color display, Also called a dot. A combination of red, green, and blue pixels constitutes one color display pixel.

  Although not shown, a polarizing plate may be attached to the outside of each of the TFT substrate 120 and the counter substrate 140 so that the two polarizing plates are opposed to each other with the liquid crystal layer 160 interposed therebetween. The transmission axes (polarization axes) of the two polarizing plates are arranged so as to be orthogonal to each other, with one arranged along the horizontal direction (row direction) and the other along the vertical direction (column direction). Alternatively, a polarizing plate may be provided in the liquid crystal panel 100. The liquid crystal layer 160 is combined with a polarizing plate arranged in a crossed Nicols state to display a normally black mode. Although not shown here, the liquid crystal panel 100 is mounted with a drive circuit for driving the liquid crystal panel 100 and a control circuit for controlling the drive circuit as necessary. The liquid crystal panel 100 is used in combination with a backlight as necessary.

  FIG. 1B shows a schematic plan view of the TFT substrate 120. Note that FIG. 1B illustrates a configuration corresponding to one pixel.

  The TFT substrate 120 is provided with a gate line G extending in the row direction (x direction), a source line S extending in the column direction (y direction), and an auxiliary capacitance line CS disposed between the adjacent gate lines G. It has been. The TFT 125 has a gate electrically connected to the gate wiring G, a source electrically connected to the source wiring S, and a drain electrically connected to the pixel electrode 124.

  The pixel electrode 124 includes a cross-shaped trunk electrode 124j and branch electrodes 124k1 to 124k4 extending from the trunk electrode 124j in four different directions d1 to d4. Such a structure of the pixel electrode is also called a fishbone structure. The trunk electrode 124j extends in the x direction and the y direction. For example, in the pixel electrode 124, the width of the trunk electrode 124j is 3 μm. The branch electrodes 124k1, 124k2, 124k3, and 124k4 have a width of 3 μm and an interval of 3 μm. Here, the horizontal direction (left-right direction) of the display screen (paper surface) is taken as a reference for the azimuth angle direction, and the counterclockwise direction is taken positively. When the counterclockwise direction is positive), the directions d1 to d4 are directed to 135 °, 45 °, 315 °, and 225 °, respectively.

  When a voltage is applied to the liquid crystal layer 160 in the liquid crystal panel 100, the liquid crystal molecules 162 are aligned parallel to the extending direction of the corresponding branch electrodes 124k1 to 124k4, as shown in FIG. The liquid crystal layer 160 includes a liquid crystal domain A formed by the branch electrode 124k1, a liquid crystal domain B formed by the branch electrode 124k2, a liquid crystal domain C formed by the branch electrode 124k3, and a liquid crystal domain formed by the branch electrode 124k4. D. When no voltage is applied to the liquid crystal layer 160 or the applied voltage is relatively low, the liquid crystal molecules 162 are aligned perpendicular to the main surface of an alignment film (not shown) except for the vicinity of the pixel electrode 124. On the other hand, when a predetermined voltage is applied to the liquid crystal layer 160, the liquid crystal molecules 162 are aligned along the extending directions d1 to d4 of the branch electrodes 124k1, 124k2, 124k3, and 124k4.

  In this specification, the alignment direction of the liquid crystal molecules in the center of the liquid crystal domains A to D is referred to as a reference alignment direction, and an azimuth component in a direction from the back surface to the front surface along the major axis of the liquid crystal molecules in the reference alignment direction (that is, The azimuth angle component projected onto the main surface of the alignment film is referred to as a reference orientation. The reference orientation characterizes the corresponding liquid crystal domain and has a dominant influence on the viewing angle characteristics of each liquid crystal domain. When the horizontal direction (left-right direction) of the display screen (paper surface) is taken as a reference for the azimuth direction, and the counterclockwise direction is positive, the difference between any two azimuths of the four liquid crystal domains A to D is 90 °. It is set to be four orientations that are substantially equal to an integral multiple of. Specifically, the reference alignment directions of the liquid crystal domains A, B, C, and D are 315 °, 225 °, 135 °, and 45 °, respectively. Thus, the viewing angle characteristics are improved by aligning the liquid crystal molecules 162 in four different orientations.

  The liquid crystal panel 100 further includes an alignment maintaining layer 130 provided on the liquid crystal layer 160 side of the TFT substrate 120 and an alignment maintaining layer 150 provided on the liquid crystal layer 160 side of the counter substrate 140. Each of the orientation maintaining layers 130 and 150 contains a polymer obtained by polymerizing a photopolymerizable compound. Polymerizing the photopolymerizable compound in the mixture with the mixture of the photopolymerizable compound and the liquid crystal compound sandwiched between the first alignment film 126 of the TFT substrate 120 and the second alignment film 146 of the counter substrate 140. Thus, the alignment maintaining layers 130 and 150 are formed, and the liquid crystal layer 160 is formed from the mixture. A trace amount of the photopolymerizable compound may remain in the liquid crystal layer 160. In the following description of the present specification, the alignment sustaining layers 130 and 150 may be referred to as a first alignment maintaining layer 130 and a second alignment maintaining layer 150, respectively.

  The alignment maintaining layers 130 and 150 maintain the liquid crystal molecules 162 in a direction slightly inclined from the normal direction of the main surface of the alignment films 126 and 146. The alignment direction of the liquid crystal molecules 162 is the alignment films 126 and 146 and the alignment layers. Defined by the maintenance layers 130, 150. The alignment maintaining layers 130 and 150 may be provided in an island shape on the alignment films 126 and 146, and a part of the surfaces of the alignment films 126 and 146 may be in contact with the liquid crystal layer 160. When the liquid crystal molecules 162 tilted and aligned according to the electric field formed in the liquid crystal layer 160 are fixed by the polymer, the tilted alignment is maintained even in the absence of an electric field. As described above, after the alignment maintaining layers 130 and 150 on the alignment films 126 and 146 are formed, the alignment maintaining layers 130 and 150 define the pretilt direction of the liquid crystal molecules 162.

Here, a polymerizable monomer having at least one ring structure or condensed ring structure and two functional groups directly bonded to the ring structure or condensed ring structure is used as the photopolymerizable compound. For example, the photopolymerizable monomer is selected from those represented by the following general formula (1).
P ¹ -A ^1- (Z ¹ -A ² ) _n -P ² (1)

In the general formula (1), P ¹ and P ² are functional groups, each independently an acrylate, methacrylate, vinyl, vinyloxy or epoxy group, and A ¹ and A ² are ring structures, each independently. Represents a 1,4-phenylene or naphthalene-2,6-diyl group, Z ¹ represents a —COO— or —OCO— group or a single bond, and n represents 0, 1, or 2.

In the general formula (1), P ¹ and P ² are preferably acrylate groups, Z ¹ is preferably a single bond, and n is preferably 0 or 1. A preferable monomer is, for example, a compound represented by the following formula.

In the structural formulas (1a) to (1c), P ¹ and P ² are as described above in the general formula (1), and particularly preferable P ¹ and P ² are acrylate groups. Further, among the above compounds, the compounds represented by Structural Formula (1a) and Structural Formula (1b) are very preferable, and the compound of Structural Formula (1a) is particularly preferable.

  A defect may be detected in a defect inspection performed after the liquid crystal panel 100 is manufactured. The defect occurs due to, for example, unevenness of ultraviolet light irradiated to form the alignment sustaining layers 130 and 150, variation in characteristics of the TFT 125, and the like, and the display quality and yield decrease due to the defect. In the present embodiment, as will be described later, the defect is corrected by irradiating with ultraviolet light to suppress the deterioration of display quality and yield.

  Hereinafter, with reference to FIG. 2, the manufacturing method and defect correction method of the liquid crystal panel 100 will be described.

  First, as shown in FIG. 2A, the pixel electrode 124 is formed on the first insulating substrate 122. Although not shown in FIG. 2A, between the first insulating substrate 122 and the pixel electrode 124, TFTs and wirings connected to them are provided. Next, a first alignment film 126 that covers the pixel electrode 124 is formed. In this way, the TFT substrate 120 is manufactured.

  As shown in FIG. 2B, the counter electrode 144 is formed on the second insulating substrate 142. Next, a second alignment film 146 is formed on the counter electrode 144. In this way, the counter substrate 140 is manufactured.

  Next, a mixture in which a liquid crystal compound and a photopolymerizable compound are mixed is prepared. Here, the photopolymerizable monomer described above is used as the photopolymerizable compound. The photopolymerizable monomer is dissolved in the liquid crystal compound. For example, the concentration of the photopolymerizable monomer with respect to the mixture is 0.30 wt%.

  Next, as shown in FIG. 2C, the liquid crystal panel 100 is manufactured using the TFT substrate 120, the counter substrate 140, and the mixture. In this case, the mixture C is sandwiched between the first alignment film 126 of the TFT substrate 120 and the second alignment film 146 of the counter substrate 140.

  For example, the liquid crystal panel 100 is manufactured as follows. A sealing agent is applied to one of the TFT substrate 120 and the counter substrate 140 in a rectangular frame shape, and the mixture is dropped into a region surrounded by the sealing agent. Thereafter, the TFT substrate 120 and the counter substrate 140 are bonded together, and the sealing agent is cured. In addition, the method of dropping the mixture in this way is also called a drop method (One Drop Filling: ODF). ODF can apply the mixture uniformly and in a short time, and batch processing can be performed on the mother glass substrate. Furthermore, the waste amount of the mixture can be reduced and the mixture can be used efficiently.

  Alternatively, after applying a sealant formed from, for example, a thermosetting resin to one of the TFT substrate 120 and the counter substrate 140 in a partially opened rectangular frame shape, the TFT substrate 120 and the counter substrate 140 are bonded together, The sealing agent is cured by heat treatment to form an empty cell. Then, after injecting a mixture between the TFT substrate 120 and the counter substrate 140, the opening may be sealed, for example, with a photo-curing sealant.

Next, as shown in FIG. 2D, ultraviolet light (for example, i-line with a wavelength of 365 nm, about 5.8 mW / cm ² ) is applied to the liquid crystal while a voltage is applied between the pixel electrode 124 and the counter electrode 144. The entire surface of the panel 100 is irradiated for about 3 to 5 minutes. In this case, a voltage higher than the voltage corresponding to the maximum luminance at the time of driving the liquid crystal panel 100 is applied between the pixel electrode 124 and the counter electrode 144. When a voltage is applied, the liquid crystal molecules 162 are aligned according to the electric field formed between the pixel electrode 124 and the counter electrode 144.

  Note that in the case where the counter substrate 140 is provided with a color filter layer, the intensity of the wavelength reaching the liquid crystal molecules 162 differs depending on the color of the pixel, so that the ultraviolet light irradiation is performed from the TFT substrate 120 side. When irradiated with ultraviolet light, the photopolymerizable monomer in the mixture C is polymerized to form a polymer. The polymer is phase-separated from the mixture C, and the liquid crystal layer 160 is formed together with the first and second alignment maintaining layers 130 and 150 containing the polymer. Thus, by forming a polymer in a state where a voltage is applied between the pixel electrode 124 and the counter electrode 144, the liquid crystal molecules 162 near the alignment films 126 and 146 are strongly regulated in this state, Thereafter, even when no voltage is applied, the liquid crystal molecules 162 maintain the inclination of the main surfaces of the alignment films 126 and 146 from the normal direction. In this specification, the process of irradiating ultraviolet light in this way may be referred to as a tilted alignment maintaining process. The inclined alignment maintaining step is generally performed at room temperature.

When the concentration of the photopolymerizable monomer remaining in the liquid crystal layer 160 after irradiation with ultraviolet light with a voltage applied between the pixel electrode 124 and the counter electrode 144 is high, the voltage holding ratio decreases, Burn-in may occur when the liquid crystal panel 100 is driven. Therefore, without applying a voltage between the pixel electrode 124 and the counter electrode 144, for example, about 1.4 mW / cm ² of ultraviolet light is applied to the entire surface of the liquid crystal panel 100 for about 1 to 2 hours using a black light. Irradiation may reduce the concentration of the photopolymerizable monomer remaining in the liquid crystal layer 160. In the present specification, the process of irradiating ultraviolet light in this way may be referred to as a residual monomer reduction process. However, here, in the residual monomer reducing step, the concentration of the photopolymerizable monomer may be lowered to some extent, and it is not necessary to completely reduce it to zero.

  Next, a defect inspection of the liquid crystal panel 100 is performed. Ideally, the first and second alignment maintaining layers 130 and 150 are uniformly dispersed, and when an input signal is input such that all pixels display the same gradation, the liquid crystal panel 100 displays a uniform display. In practice, the display on the liquid crystal panel 100 may not be uniform. In the defect inspection, an input signal such that all pixels display the same intermediate gradation is input to the liquid crystal panel 100, and a pixel having a luminance different from that of the other pixels is detected in the liquid crystal panel 100. 100 normal and defective areas are identified. Due to the intermediate gradation display, a subtle difference in gradation due to the variation of the dose appears remarkably.

  Defects may occur due to unevenness of ultraviolet light irradiation in the tilt alignment maintaining step. For example, when dust or the like is present on the ultraviolet light path toward the liquid crystal panel 100, the liquid crystal panel 100 has a region where the ultraviolet light is not sufficiently irradiated. Alternatively, in the tilt alignment maintaining step, when the spot area of the ultraviolet light is sufficiently smaller than the liquid crystal panel 100, it is necessary to scan the ultraviolet light relative to the liquid crystal panel 100. In some areas of the liquid crystal panel 100, ultraviolet light irradiation may not be performed uniformly. Thus, if there is unevenness in the irradiation of ultraviolet light in the tilted alignment maintaining step, the alignment maintaining layers 130 and 150 are not uniformly formed in the region, resulting in a defect.

  For example, when there is a region where the liquid crystal panel 100 is not sufficiently irradiated with ultraviolet light, the alignment maintaining layers 130 and 150 are not sufficiently formed in the region, so that the defect region looks darker than the normal region. On the contrary, when the liquid crystal panel 100 has a region where the ultraviolet light is excessively irradiated, the alignment maintaining layers 130 and 150 are excessively formed in the region. Also looks bright.

  Next, as shown in FIG. 2E, defect correction is performed by irradiating the defect region of the liquid crystal panel 100 with ultraviolet light so that the normal region of the liquid crystal panel 100 is not irradiated with ultraviolet light. For example, irradiation with ultraviolet light is performed using a mask M having a light shielding region and a light transmission region. The mask M is arranged such that the light shielding area corresponds to a normal area of the liquid crystal panel 100 and the light transmission area corresponds to a defective area of the liquid crystal panel 100. The alignment maintaining layers 130 and 150 are formed in the defect region by irradiation with ultraviolet light. Similar to the alignment maintaining layers 130 and 150 formed in the above-described tilt alignment maintaining step, the alignment maintaining layers 130 and 150 include a polymer obtained by polymerizing a photopolymerizable monomer. As described above, the alignment maintaining layers 130 and 150 separately formed in the defect region cause the defect region to exhibit the same luminance as the normal region, and the defect is corrected. Thus, defect correction is performed using a photopolymerizable monomer.

  For example, when the defect area is darker than the normal area, the defect area is irradiated with light transmitted through the light transmission area of the mask M in a state where a voltage is applied between the pixel electrode 124 and the counter electrode 144. Here, since it is difficult to irradiate the defect area with light in a state where a voltage is applied only to the pixel in the defective area, the voltage is applied to the entire pixel. In this case, the liquid crystal molecules 162 in the defect region are aligned with a large inclination from the normal direction of the main surfaces of the alignment films 126 and 146 due to the defect correction, and the defect region becomes bright.

  When the defect area is brighter than the normal area, the defect area is irradiated with light transmitted through the light transmission area of the mask M without applying a voltage between the pixel electrode 124 and the counter electrode 144. In this case, the liquid crystal molecules 162 in the defect region are aligned in a state close to the normal direction of the main surfaces of the alignment films 126 and 146 due to the defect correction, and the defect region becomes dark.

  As described above, the defect of the liquid crystal panel 100 is corrected, and the defect area can be displayed in the same manner as the normal area. Further, in the present embodiment, defects can be corrected without destroying the liquid crystal panel 100 after the liquid crystal panel 100 is manufactured, and a decrease in display quality and yield of the liquid crystal panel 100 can be suppressed. Thereafter, a polarizing plate (not shown) may be attached to the liquid crystal panel 100 as necessary to mount the drive circuit and the control circuit.

  A defect may occur due to, for example, variation in characteristics of the TFT 125. Here, it is assumed that TFTs 125 having different voltage-current characteristics are TFTs 125a and 125b, and the TFTs 125a and 125b correspond to the pixels Pa and Pb and the pixel electrodes 124a and 124b, respectively.

  As shown in FIG. 3A, since the voltage-current characteristic of the TFT 125b is different from the voltage-current characteristic of the TFT 125a, the current flowing through the TFT 125b is the current flowing through the TFT 125a even when a voltage corresponding to a certain intermediate gradation is applied. Lower than. In this case, even if the voltages applied to the source wiring and the gate wiring corresponding to the TFTs 125a and 125b are equal, the amount of charge charged in the pixel electrodes 124a and 124b is different. Therefore, as shown in FIG. The transmittance of Pb is lower than the transmittance of the pixel Pa, and the pixel Pb is darker than the pixel Pa. By performing defect correction also in such a liquid crystal panel 100, as shown in FIG. 3C, the transmittance of the pixel Pb is made substantially equal to the transmittance of the pixel Pa, and the pixel Pb has substantially the same brightness as the pixel Pa. Can be.

  The light transmission region of the mask M described above is preferably provided corresponding to the shape of the defect region of the liquid crystal panel 100. In this case, the mask M is provided with light transmissive regions of various shapes, and the light transmissive region to be used may be changed according to the shape of the defect region.

  In the above description, the defect correction is performed using the mask M, but the present invention is not limited to this.

  Here, with reference to FIG. 4, a defect detection and correction apparatus 300 suitable for performing the above-described defect correction will be described. In this defect detection and correction apparatus 300, the liquid crystal panel 100 before the polarizing plate is attached or the liquid crystal panel 100 of the type in which the polarizing plate is not provided is mounted.

  The defect detection and correction apparatus 300 includes a mounting table 320, an illumination device 340, and a main body 360. The liquid crystal panel 100 is mounted on the mounting table 320. The liquid crystal panel 100 is disposed so that the TFT substrate 120 is in contact with the main surface of the mounting table 320. The mounting table 320 is provided so as to be movable relative to at least the main body 360.

  The lighting device 340 includes a light emitting unit 342, a wavelength filter 344, a glass table 346, and a polarizing plate 348. Of the light emitted from the light emitting unit 342, light having a wavelength in the ultraviolet region having a strong influence on the alignment of liquid crystal molecules is cut by the wavelength filter 344. A general glass plate is used as the glass table 346. The polarizing plate 348 is the same type as that attached to the outside of the liquid crystal panel 100 when a liquid crystal display device including the liquid crystal panel 100 is manufactured.

  The main body 360 includes a light source 362, a total reflection mirror 364, a wavelength selection filter 366, a slit 368, a power filter 370, a polarizing plate 372, an optical unit 374, and an objective lens 376. The polarizing plate 372 is the same type as that attached to the outside of the liquid crystal panel 100 when a liquid crystal display device including the liquid crystal panel 100 is manufactured. The optical unit 374 includes an epi-illumination light source 374a and a camera 374b, and light emitted from the epi-illumination light source 374a passes through the objective lens 376 and is reflected by the liquid crystal panel 100. Pixels can be imaged. Other components of the main body 360 will be described later.

  The defect detection and correction apparatus 300 operates as follows. First, the defect detection and correction apparatus 300 inputs an input signal in which all pixels exhibit the same gradation to the liquid crystal panel 100 in order to specify a normal area and a defective area. The liquid crystal panel 100 is provided with neither a polarizing plate nor a backlight mounted on the liquid crystal display device including the liquid crystal panel 100, but the lighting device 340 and the polarizing plate 372 (including the polarizing plate 348) are mounted on the liquid crystal display device. Since it functions in the same manner as the polarizing plate and the backlight, the same behavior as that of the liquid crystal display device can be observed. Light emitted from the illumination device 340 and transmitted through the liquid crystal panel 100 passes through the polarizing plate 372 and enters the camera 374b. The presence or absence of a defect in the liquid crystal panel 100 can be confirmed from the image captured by the camera 374b.

  After the defect area is specified, the defect detection and correction apparatus 300 corrects the defect. The light source 362 emits light including an ultraviolet light component having a wavelength of 300 to 380 nm. As the light source 362, for example, a light emitting diode (LED), a laser, a halogen lamp, a metal halide lamp, a mercury lamp, a xenon lamp, or the like is preferably used. The total reflection mirror 364 totally reflects the light emitted from the light source 362.

  The wavelength selection filter 366 cuts a wavelength component that adversely affects the liquid crystal molecules 162 (see FIG. 1A) in the light emitted from the light source 362. Next, the size and shape of the spot light are adjusted by the slit 368. Note that in the case where light emitted from the light source 362 includes various wavelengths, the stray light may be cut by forming a slit 368 by combining an aperture or the like. The intensity of ultraviolet light is controlled by the power filter 370. The objective lens 376 enlarges or reduces the spot light size according to the defect area of the liquid crystal panel 100. As described above, the defect is corrected by irradiating the defect region of the liquid crystal panel 100 with the ultraviolet light adjusted to correspond to the defect region. As described above, the defect detection and correction apparatus 300 is preferably used for detecting and correcting defects.

  In the above description, the defect correction is performed after the tilt alignment maintaining step and the residual monomer reducing step, but the present invention is not limited to this. Defect correction may be performed after the tilt alignment maintaining step and before the residual monomer reducing step. In this case, the photopolymerizable monomer remaining in the liquid crystal layer 160 in the residual monomer reduction step may be made substantially zero.

  In the above description, the cause of the defect has been described as the unevenness of ultraviolet light and the variation in the characteristics of the TFT 125 in the tilt alignment maintaining step, but the cause of the defect is not limited to this. For example, when the voltage of the auxiliary capacitance line CS is changed every predetermined horizontal scanning period in the liquid crystal panel 100, if the electric capacitance between the auxiliary capacitance line CS and the pixel electrode 124 is not uniform, the luminance fluctuates, resulting in a defect. May occur. Alternatively, defects may occur due to variations in TFT characteristics, insufficient parasitic capacitance such as source wiring and gate wiring, and insufficient alignment performance of the polyimide alignment film. Also in this case, the defect can be corrected by irradiating the defect region with ultraviolet light.

(Embodiment 2)
In the above description, the tilt alignment maintaining step and the residual monomer reducing step are performed, but the present invention is not limited to this. The inclined alignment maintaining step and the residual monomer reducing step may not be performed.

  Hereinafter, the liquid crystal panel 100A of the present embodiment will be described with reference to FIG. The liquid crystal panel 100A of the present embodiment is described above with reference to FIG. 1 except that the alignment maintaining layers 130 and 150 provided on the liquid crystal layer 160 side of the first and second alignment films 126 and 146 are very few. The liquid crystal panel 100 has the same configuration as that of the first embodiment, and redundant description is omitted to avoid redundancy. Although details will be described later, in the liquid crystal panel 100A, the alignment maintaining layers 130 and 150 are provided in a region identified as a defective region in the defect inspection.

  Hereinafter, a defect correction method for the liquid crystal panel 100A of the present embodiment will be described with reference to FIG.

  First, as shown in FIG. 6A, a liquid crystal panel 100A having a TFT substrate 120, a counter substrate 140, and a liquid crystal layer (mixture) 160 is prepared. The liquid crystal layer 160 contains not only a liquid crystal compound but also a photopolymerizable compound, but the concentration of the photopolymerizable compound in the liquid crystal layer 160 is higher than the concentration of the polymerizable compound in the mixture when the liquid crystal panel 100 is manufactured. Low. The liquid crystal panel 100A is manufactured in the same manner as the liquid crystal panel 100 described above with reference to FIGS. 2 (a) to 2 (c).

  Next, a defect inspection of the liquid crystal panel 100A is performed. An input signal such that all pixels display the same intermediate gradation is input to the liquid crystal panel 100A, and pixels having a luminance different from those of other pixels are detected in the liquid crystal panel 100A. Identify defective areas. Thereafter, as shown in FIG. 6B, defect correction is performed by irradiating the defect region of the liquid crystal panel 100A with ultraviolet light without irradiating the normal region of the liquid crystal panel 100A with ultraviolet light. By this irradiation, alignment maintaining layers 130 and 150 are formed in the defect region. For example, the ultraviolet light irradiation may be performed using a mask M having a light shielding region and a light transmission region, or may be performed by the defect detection and correction apparatus 300 described above with reference to FIG.

  As described above, the defect correction of the liquid crystal panel 100A is performed, and the display of the defective area can also display the same display as the normal area. Thereafter, a polarizing plate (not shown) may be attached to the liquid crystal panel 100A as necessary to mount the drive circuit and the control circuit.

  In the above description, the pixel electrodes 124 of the liquid crystal panels 100 and 100A have a fishbone structure, but the present invention is not limited to this. The liquid crystal panels 100 and 100A may be in a so-called MVA mode or CPA mode. Alternatively, the liquid crystal panel 100 may be in another mode.

  For example, the liquid crystal panel may be in a VATN mode. Hereinafter, the VATN mode liquid crystal panel 100B will be described with reference to FIGS. FIG. 7 shows a schematic diagram of the liquid crystal panel 100B. In the liquid crystal panel 100B, the first and second alignment films 126B and 146B are photo-alignment films on which photo-alignment processing has been performed, and the pixel electrode 124 does not have a fishbone structure (typically has a rectangular shape). ) Except for the above points, it has the same configuration as the liquid crystal panel 100A described above with reference to FIG. 5, and redundant description is omitted to avoid redundancy.

  8A shows the pretilt direction of the liquid crystal molecules 162 defined in the alignment film 126B of the TFT substrate 120, and FIG. 8B shows the liquid crystal defined in the alignment film 146B of the counter substrate 140. The pretilt direction of the molecule 162 is shown. FIG. 8C shows the alignment direction of the liquid crystal molecules 162 at the center of the liquid crystal domains A to D in the voltage application state. Each of FIG. 8A to FIG. 8C schematically shows the alignment direction of the liquid crystal molecules 162 when viewed from the observer side, and the end portions (substantially circular portions) of the cylindrical liquid crystal molecules 162 are shown. ) Indicates tilting toward the observer.

  As shown in FIG. 8A, the first alignment film 126B has alignment regions OR1 and OR2. The liquid crystal molecules 162 defined in the alignment region OR1 are inclined in the −y direction from the normal direction of the main surface of the first alignment film 126B, and the liquid crystal molecules 162 defined in the alignment region OR2 are aligned with the first alignment film 126B. It is inclined in the + y direction from the normal direction of the main surface. In addition, the boundary line between the alignment region OR1 and the alignment region OR2 extends in the column direction (y direction) and is positioned at the approximate center in the row direction (x direction) of each pixel.

  The alignment region OR1 of the first alignment film 126B is subjected to alignment treatment in the alignment treatment direction PD1, and the alignment region OR2 is subjected to alignment treatment in the alignment treatment direction PD2 antiparallel to the alignment treatment direction PD1. Yes. Here, the alignment treatment direction corresponds to an azimuth component obtained by projecting the direction toward the alignment region along the major axis of the liquid crystal molecules 162 onto the alignment region.

  Further, as shown in FIG. 8B, the second alignment film 146B has alignment regions OR3 and OR4. The liquid crystal molecules 162 defined in the alignment region OR3 are inclined in the + x direction from the normal direction of the main surface of the second alignment film 146B, and the end of the liquid crystal molecules 162 in the −x direction faces the front side. Further, the liquid crystal molecules 162 defined in the alignment region OR4 are inclined in the −x direction from the normal direction of the main surface of the second alignment film 146B, and the + x direction end of the liquid crystal molecules 162 faces the front side. Yes. The alignment region OR3 of the second alignment film 146B is subjected to alignment treatment in the alignment treatment direction PD3, and the alignment region OR4 is subjected to alignment treatment in the alignment treatment direction PD4 antiparallel to the alignment treatment direction PD3. Yes. The TFT substrate 120 and the counter substrate 140 are bonded so that the alignment treatment directions of the regions where the first and second alignment films 126B and 146B face each other are orthogonal to each other.

  As shown in FIG. 8C, four liquid crystal domains A, B, C and D are formed in the liquid crystal layer of the pixel. A portion of the liquid crystal layer 160 sandwiched between the alignment region OR1 of the first alignment film 126B and the alignment region OR3 of the second alignment film 146B becomes the liquid crystal domain A, and the alignment region OR1 of the first alignment film 126B and the second alignment film The portion sandwiched between the alignment region OR4 of 146B becomes the liquid crystal domain B, and the portion sandwiched between the alignment region OR2 of the first alignment film 126B and the alignment region OR4 of the second alignment film 146B becomes the liquid crystal domain C, and the first alignment film A portion sandwiched between the alignment region OR2 of 126B and the alignment region OR3 of the second alignment film 146B becomes the liquid crystal domain D. The angle formed between the alignment treatment directions PD1 and PD2 and the alignment treatment directions PD3 and PD4 is approximately 90 °, and the twist angle in each liquid crystal domain is approximately 90 °.

  The alignment direction of the liquid crystal molecules 162 at the center of the liquid crystal domains A to D is an intermediate direction between the pretilt direction of the liquid crystal molecules 162 by the first alignment film 126B and the pretilt direction of the liquid crystal molecules 162 by the second alignment film 146B. Of the reference alignment directions indicating the alignment direction of the liquid crystal molecules 162 in the center of the liquid crystal domain, the azimuth component in the direction from the back surface to the front surface along the major axis of the liquid crystal molecules 162 (that is, the reference alignment direction is the first alignment film 126B The azimuth angle component projected onto the main surface of the second alignment film 146B is also referred to as a reference alignment direction. The reference orientation characterizes the corresponding liquid crystal domain and has a dominant influence on the viewing angle characteristics of each liquid crystal domain. Here, the horizontal direction (left-right direction) of the display screen (paper surface) is taken as a reference for the azimuth angle direction, and the counterclockwise direction is taken positively. The reference orientation directions of the four liquid crystal domains A to D are set so that the difference between any two directions is four directions substantially equal to an integral multiple of 90 °. Specifically, the reference orientation directions of the liquid crystal domains A, B, C, and D are 225 °, 315 °, 45 °, and 135 °, respectively.

  Hereinafter, a defect correction method for the liquid crystal panel 100B will be described with reference to FIG.

A TFT substrate 120 is formed. For example, the alignment film 126B of the TFT substrate 120 is formed as follows. A material having a photosensitive group is used as the material of the alignment film 126B. The material of the alignment film 126B has, for example, at least one photosensitive group selected from the group consisting of a 4-chalcone group, a 4′-chalcone group, a coumarin group, and a cinnamoyl group. After applying this material by spin casting, the alignment film 126B is formed by baking at about 180 ° C. for 60 minutes. Thereafter, a photo-alignment process is performed on the alignment film 126B. For example, light is irradiated from the main surface side of the alignment film 126B with P-polarized light having a wavelength of 365 nm and an intensity of 3 mW / cm ² for 400 seconds with respect to the normal direction of the main surface of the alignment film 126B. An alignment process is performed.

  Further, the counter substrate 140 is formed. A photo-alignment process is performed on the alignment film 146B of the counter substrate 140 in the same manner as the alignment film 126B.

  Thereafter, as shown in FIG. 9A, a liquid crystal panel 100B in which a liquid crystal layer (mixture) 160 is provided between the TFT substrate 120 and the counter substrate 140 is formed. The liquid crystal layer 160 contains not only a liquid crystal compound but also a photopolymerizable compound. In the liquid crystal panel 100B, when no voltage is applied, the liquid crystal molecules 162 in the vicinity of the first alignment film 126B and in the vicinity of the second alignment film 146B are in the normal direction of the main surfaces of the first and second alignment films 126B and 146B. Tilted. For example, the pretilt angle is 88.5 degrees.

  Next, as shown in FIG. 9B, the liquid crystal panel 100B is inspected for defects. An input signal in which all pixels display the same intermediate gray level is input to the liquid crystal panel 100B, and pixels having luminance different from those of other pixels are detected in the liquid crystal panel 100B. Identify defective areas. Thereafter, the defect region of the liquid crystal panel 100B is irradiated with ultraviolet light without irradiating the normal region of the liquid crystal panel 100B with ultraviolet light, and the defect is corrected. By this irradiation, alignment maintaining layers 130 and 150 are formed in the defect region. Irradiation with ultraviolet light is performed using a mask M having a light shielding region and a light transmission region. The defect correction may be performed using the defect detection and correction apparatus 300 described above with reference to FIG.

  In the liquid crystal panel 100B described above, the first and second alignment films 126B and 146B are subjected to the photo-alignment process, and the PSA process is not performed before the defect inspection. A PSA process may be further performed before.

  In the liquid crystal panel 100B, the optical alignment process is performed on both the first alignment film 126B and the second alignment film 146B, but the present invention is not limited to this. One of the first alignment film 126B and the second alignment film 146B may be subjected to a photo-alignment process, and the other may not be subjected to a photo-alignment process.

  According to the present invention, the defect of the liquid crystal panel can be easily corrected. Further, according to the present invention, it is possible to provide a liquid crystal panel that can be manufactured with a high yield.

DESCRIPTION OF SYMBOLS 100 Liquid crystal panel 120 TFT substrate 122 Insulating substrate 124 Pixel electrode 126 Alignment film 130 Alignment maintenance layer 140 Counter substrate 142 Insulation substrate 144 Counter electrode 144a Conductive part 144b Non-conductive part 146 Alignment film 150 Alignment maintenance layer 160 Liquid crystal layer 162 Liquid crystal molecule

Claims (10)

A TFT substrate having a pixel electrode and a first alignment film, a counter substrate having a counter electrode and a second alignment film, and a liquid crystal compound and a photopolymerizable compound provided between the TFT substrate and the counter substrate Preparing a liquid crystal panel comprising a mixture;
Identifying a normal region and a defective region of the liquid crystal panel;
Irradiating the defect area of the liquid crystal panel with ultraviolet light so as not to irradiate the normal area of the liquid crystal panel with ultraviolet light.   Before specifying the defective area of the liquid crystal panel, the entire surface of the liquid crystal panel is irradiated with ultraviolet light in a state where a voltage is applied between the pixel electrode and the counter electrode. The defect correction method for a liquid crystal panel according to claim 1, further comprising forming an alignment maintaining layer on each mixture side of the second alignment film.   3. The liquid crystal according to claim 2, further comprising a step of irradiating the entire surface of the liquid crystal panel with ultraviolet light in a state where no voltage is applied between the pixel electrode and the counter electrode after the alignment maintaining layer is formed. Panel defect correction method.   The defect of the liquid crystal panel according to claim 3, wherein the step of irradiating the ultraviolet light without applying a voltage between the pixel electrode and the counter electrode is performed after the defect region of the liquid crystal panel is specified. How to fix.   The defect correction of the liquid crystal panel according to claim 3, wherein the defect region of the liquid crystal panel is specified after the irradiation with the ultraviolet light without applying a voltage between the pixel electrode and the counter electrode. Method. Before the step of irradiating the defect region with the ultraviolet light, further comprising the step of preparing a mask having a light shielding region and a light transmission region;
In the step of irradiating the defect area with the ultraviolet light, the light shielding area of the mask corresponds to the normal area of the liquid crystal panel, and the light transmission area of the mask corresponds to the defect area of the liquid crystal panel. The defect correction method of the liquid crystal panel in any one of Claim 1 to 5 including the process of arrange | positioning the said mask with respect to the said liquid crystal panel.   The defect correction of the liquid crystal panel according to claim 1, wherein the step of irradiating the defect region with the ultraviolet light includes a step of adjusting the ultraviolet light so as to correspond to the defect region of the liquid crystal panel. Method.   The liquid crystal panel defect according to claim 1, wherein the step of preparing the liquid crystal panel includes a step of performing photo-alignment treatment on at least one of the first alignment film and the second alignment film. How to fix. A liquid crystal panel provided with a plurality of pixels including a first pixel and a second pixel,
A plurality of pixel electrodes including a first pixel electrode defining the first pixel and a second pixel electrode defining the second pixel; a first thin film transistor corresponding to the first pixel electrode; and a second pixel electrode corresponding to the second pixel electrode A plurality of thin film transistors including a second thin film transistor, and a TFT substrate having a first alignment film;
A counter substrate having a counter electrode and a second alignment film;
A liquid crystal layer sandwiched between the first alignment film and the second alignment film;
An alignment maintaining layer provided on the liquid crystal layer side of each of the first alignment film and the second alignment film,
The voltage-current characteristic of the first thin film transistor is different from the voltage-current characteristic of the second thin film transistor, and the voltage-transmittance characteristic of the first pixel is substantially equal to the voltage-transmittance characteristic of the second pixel.   The liquid crystal panel according to claim 9, wherein at least one of the first alignment film and the second alignment film is a photo-alignment film.

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