JP2008242035A - Liquid crystal display panel and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display panel which can be manufactured in a manufacturing method simpler than the conventional one and has structure by which generation of low temperature air bubbles is suppressed and a manufacturing method thereof. <P>SOLUTION: The liquid crystal display panel is provided with a first substrate 10, a liquid crystal layer 30 and a second substrate 20 arranged so as to be opposite to the first substrate via the liquid crystal layer. The first substrate has a plurality of pillar structures 15a and 15b substantially of the same height provided on a predetermined position on the side of the liquid crystal layer and the second substrate has a plurality of recessed parts 24b at a position opposite to a part 15b preliminarily selected among the plurality of pillar structures. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display panel and a manufacturing method thereof.

  Liquid crystal display devices are characterized by their small size, thinness, low power consumption, and light weight, and are currently widely used in various electronic devices. In particular, an active matrix liquid crystal display device having a switching element is widely used for OA equipment such as a personal computer, AV equipment such as a television, a mobile phone, and a vehicle-mounted application. In recent years, liquid crystal display devices have been rapidly improved in display quality, such as upsizing, high definition, improvement in pixel effective area ratio (high aperture ratio), wide viewing angle, or improvement in color purity. .

  A liquid crystal display device generally includes a liquid crystal display panel having a pair of substrates (for example, an active matrix substrate and a color filter substrate) disposed so as to face each other, and a liquid crystal layer disposed between the pair of substrates; And a driving circuit for supplying a predetermined signal and voltage to the liquid crystal display panel. Further, the transmissive or transflective liquid crystal display device includes an illumination device such as a backlight. A part of the drive circuit may be formed integrally with the liquid crystal display panel. Recently, liquid crystal televisions equipped with TV receivers are rapidly spreading.

  In a liquid crystal display panel, the thickness of a liquid crystal layer (sometimes called a cell gap) is defined by a member called a spacer. As the spacer, granular spacers such as plastic beads, and columnar spacers (sometimes referred to as “dot spacers” or “photo spacers”) formed using a photosensitive resin on a substrate are used. Although the thickness of the liquid crystal layer depends on the display mode, for example, in a vertical alignment mode (VA mode) liquid crystal panel that has been widely used in recent years, it directly affects retardation. It is important to set and maintain the value. In a display device equipped with a portable electronic device or a touch panel, a force is often applied from the outside to the display surface of the liquid crystal display panel. In such a case, the thickness of the liquid crystal layer is maintained or short. It is required to return to a predetermined thickness over time. This characteristic of the liquid crystal display panel is sometimes referred to as “pressure resistance”. In particular, in a liquid crystal panel characterized by thinness, the response to pressing becomes remarkable.

  The pressure resistance of the liquid crystal display panel can be improved by increasing the density of the spacers (the number of spacers per unit area). However, when the density of the spacer is increased, there is a problem that “cold bubbles” are generated. “Low-temperature bubbles” are bubbles that are generated when the liquid crystal display panel is placed at a low temperature, and are generated because the spacer cannot follow the volume reduction of the liquid crystal layer due to thermal contraction of the liquid crystal material or the substrate cannot be deformed. .

Patent Document 1 discloses a liquid crystal display panel in which the generation of low temperature bubbles is suppressed. The technique described in Patent Document 1 has two types of columnar spacers (columnar structures according to the definition in the present specification) having different heights, and the lower one within the elastic deformation range of the higher columnar spacer. The height of the columnar spacer is set so that an external load is also applied to the columnar spacer. Only the higher columnar spacer absorbs the contraction of the thickness of the liquid crystal layer accompanying the temperature change, and reduces the generation of low-temperature bubbles.
JP 2003-84289 A

  However, columnar spacers having different heights are formed as described in Patent Document 1 (to be precise, this means that the distance from the surface of the substrate to the apex of the columnar spacers is different). For this reason, there is a problem that the manufacturing process becomes complicated, and the manufacturing efficiency decreases and the cost increases. For example, as described in the first embodiment of Patent Document 1, when the columnar spacers having different heights are formed by varying the thickness of the color filter layer serving as the base of the columnar spacer, The color material density needs to be adjusted so that the color of the color filter does not change due to the difference in thickness, which complicates the manufacturing process of the color filter substrate. Further, Patent Document 1 describes, as a modified example, that the length of the columnar spacer formed using the photosensitive resin may be varied, but a specific example for forming such a columnar spacer. This method is not described. When the columnar spacers having different heights are individually formed, naturally, the number of photolithography processes is increased.

  The present invention has been made in order to solve the above-mentioned problems, and its main object is to produce a liquid crystal display panel having a structure in which the generation of low-temperature bubbles is suppressed, which can be produced by a simpler production method than before, and the production thereof. It is to provide a method.

A liquid crystal display panel according to the present invention includes a first substrate, a liquid crystal layer, and a second substrate disposed so as to face the first substrate with the liquid crystal layer interposed therebetween, and includes a display region including a plurality of pixels. The first substrate has a plurality of columnar structures having substantially the same height provided at predetermined positions on the liquid crystal layer side, and the second substrate. The substrate has a plurality of recesses at positions facing a preselected part of the plurality of columnar structures.
In one embodiment, among the plurality of columnar structures, the columnar structures disposed at positions facing the plurality of recesses do not contact the second substrate in a state where the columnar structures are allowed to stand at room temperature.

  In one embodiment, the depth of the plurality of recesses is 0.3 μm or more.

  In one embodiment, the second substrate has a transparent substrate, a circuit element provided on the transparent substrate, and an insulating layer covering the circuit element, and the plurality of recesses are formed in the insulating layer. ing.

  In one embodiment, the insulating layer is made of a photosensitive resin.

  In one embodiment, the plurality of recesses are provided in an outer peripheral portion of the plurality of pixels in the display area.

  In one embodiment, the first substrate has a counter electrode, and the plurality of columnar structures include a photosensitive resin layer formed on the counter electrode.

  A display device according to the present invention includes any one of the liquid crystal display panels described above.

  The method for producing a liquid crystal display panel of the present invention includes a step (a) of preparing a first transparent substrate having a plurality of columnar structures having substantially the same height at a predetermined position, and a subsequent step ( a step (b) of preparing a second substrate having a plurality of recesses at a position facing a preselected part of the plurality of columnar structures when being bonded to the first substrate in c); And a step (c) of bonding the first substrate and the second substrate through the plurality of columnar structures.

  According to the present invention, since it is only necessary to form a plurality of columnar structures having substantially the same height on one substrate (typically a color filter substrate), in order to vary the height of the columnar structures. Does not require a special process. Further, the recess provided in the other substrate (typically the TFT substrate) only needs to be formed when patterning an insulating layer formed in a conventional TFT substrate manufacturing process, for example, a photomask, for example. You just need to change. Thus, according to the present invention, there are provided a liquid crystal display panel having a structure in which the generation of low-temperature bubbles can be suppressed and a method for manufacturing the same, which can be manufactured by a simpler manufacturing method than before.

  A structure of a liquid crystal display panel according to an embodiment of the present invention and a manufacturing method thereof will be described below with reference to the drawings.

  FIG. 1 is a diagram schematically showing a cross-sectional structure of a liquid crystal display panel 100 according to an embodiment of the present invention.

  The liquid crystal display panel 100 includes a color filter substrate 10, a liquid crystal layer 30, and a TFT substrate 20 disposed so as to face the color filter substrate 10 with the liquid crystal layer 30 in between, and includes a plurality of pixels. Has a region. A peripheral area outside the display area is called a frame area.

  The plurality of pixels are generally arranged in a matrix having rows and columns. FIG. 1 shows three pixels adjacent to each other in the row direction. Here, it has a pixel displaying blue with the blue color filter 13B, a pixel displaying red with the red color filter 13R, and a pixel displaying green with the green color filter 13G, and these three pixels are The example which comprises one color display pixel is shown. Of course, a pixel including a color filter of another color is not limited to these three primary colors, and the color filter may be omitted. Each pixel 13 has a counter electrode 14, a pixel electrode 26, and a liquid crystal layer 30 provided therebetween, and displays a voltage by controlling the voltage applied to the liquid crystal layer 30 for each pixel. Do. The pixel electrode 26 is provided on the TFT substrate 20 and is supplied with a display signal voltage via a TFT (not shown). A predetermined common voltage (counter voltage) is supplied to the counter electrode 14. Since the pixel configuration and driving method of the TFT type liquid crystal display panel are well known, the details are omitted. Hereinafter, the configuration of the liquid crystal display panel 100 will be described in detail.

  The color filter substrate 10 includes a transparent substrate (for example, a glass substrate) 11, a black matrix 12 and a color filter layer 13 formed on the substrate 11, and a counter electrode 14 that covers the black matrix 12 and the color filter layer 13. ing. The black matrix 12 is made of, for example, a black resin or a metal such as chromium (Cr). The counter electrode 14 is made of a transparent conductive material such as ITO. If necessary, an alignment film (not shown) and an alignment regulating structure (for example, a rib (projection) for MVA mode) are provided on the surface of the counter electrode 14 on the liquid crystal layer 30 side.

  Columnar spacers 15 a and 15 b are provided on the counter electrode 14 on the liquid crystal layer 30 side. Here, the columnar spacer 15a is provided corresponding to the R pixel, and the columnar spacer 15b is provided corresponding to the G pixel. A columnar spacer corresponding to the B pixel is not provided. Therefore, the total number of columnar spacers 15a and 15b provided in the display area is 2/3 of the number of pixels.

  The columnar spacers 15a and 15b are formed by patterning the photosensitive resin layer using a photolithography process, and have substantially the same size and shape. Here, “substantially the same” means within the range of variations in the manufacturing process, and the height and thickness (typically diameter) of the columnar spacers are positively determined according to the position of the columnar spacers. This means that the manufacturing process is not adopted.

  The columnar spacers 15a and 15b have substantially the same height (length), and are provided only at different positions. That is, the columnar spacers 15a and 15b are distinguished depending on whether a recess 24b is formed (15b) or not (15a) at a position facing the TFT substrate 20 described later. The columnar spacer is provided to control the gap between the color filter substrate 10 and the TFT substrate 20 (that is, the thickness of the liquid crystal layer 30), but the gap is not determined only by the height of the columnar spacer. That is, as described in Patent Document 1, even if the height (length) of the columnar spacer itself is the same, by changing the thickness of the underlayer (color filter in Patent Document 1), The height from the surface of the substrate 11 to the top of the columnar spacer (end on the liquid crystal layer side) can be varied. In this specification, what exists from the surface of the substrate 11 to the top of the columnar spacer is called a columnar structure, and the height of the columnar structure is the same as that of the columnar spacer from the surface of the substrate 11. It means that the distance to is the same.

  Here, the columnar spacers 15a and 15b have the same height and the underlying structure is the same, and the columnar structure including the columnar spacer 15a and the columnar structure including the columnar spacer 15b have the same height. Have. For simplicity, the reference numerals of the columnar spacers included therein may be used as the reference numerals of the columnar structures. The bases of the columnar spacers 15 a and 15 b are the counter electrode 14, the color filter layer 13, and the black matrix 12. Of course, the configuration of the base is not limited to this, and the thickness (height) of the bases of the columnar spacers 15a and 15b may be the same. Depending on the liquid crystal display panel such as the configuration of the color filter layer and the configuration of the black matrix 12 May be different. For example, various configurations may be employed such as omitting the black matrix 12 or increasing the width of the black matrix 12 so that the color filter layer 13 does not serve as a base. Although not shown, the frame region is also provided with the same columnar spacers as the columnar spacers 15a and 15b, and the underlying structure is the same as the columnar spacers 15a and 15b in the display region.

  Thus, since the counter substrate 10 has the columnar structures 15a and 15b having substantially the same height, the counter substrate 10 can be manufactured by the same method as a conventional counter substrate that does not take measures against the problem of low temperature bubbles. The arrangement density, height, size (typically diameter), and arrangement position of the columnar structures (columnar spacers) can be appropriately set as in the conventional case.

  The TFT substrate 20 includes a transparent substrate (for example, a glass substrate) 21, a circuit element (including TFT and wiring) 22 formed on the transparent substrate 21, an insulating layer 24 covering the circuit element 22, and an insulating layer 24. The pixel electrode 26 is formed. As necessary, an alignment film (not shown) is provided on the surface of the pixel electrode 26 on the liquid crystal layer 30 side. The pixel electrode 26 is made of a transparent conductive material such as ITO. The insulating layer 24 is made of, for example, a photosensitive resin. The pixel electrode 26 is connected to a circuit element 22 (for example, a drain electrode of a TFT) in a contact hole 24 a formed in the insulating layer 24.

  A concave portion 24 b is provided in the outer peripheral portion of the insulating layer 24 (a portion where the pixel electrode 26 does not exist). Here, the recess 24b is formed only at a position facing the columnar spacer 15b provided corresponding to the G pixel. The recess 24b is formed, for example, by patterning the photosensitive resin layer using a photolithography process. In the example shown here, since the recess 24b can be formed by the same process when the contact hole 24a of the insulating layer 24 is formed, the manufacturing process is not complicated. As exemplified here, it is most preferable to form the recess 24b in the process of forming the insulating layer 24 using a photosensitive resin. However, the method is not limited to this, and the surface of the TFT substrate 20 on the liquid crystal layer 30 side is not limited. If a desired recess can be formed, the advantage that the color filter substrate 10 can be manufactured by a conventional manufacturing method is obtained. That is, it is not necessary to change the process for manufacturing the color filter substrate 10 depending on the model or the like, and it is possible to produce liquid crystal panels having different pressure resistance using the same color filter.

  The liquid crystal display panel 100 is obtained by bonding the color filter substrate 10 on which the columnar structures 15a and 15b are formed and the TFT substrate 20 on which the recess 24b is formed as described above, and injecting a liquid crystal material. Except for the step of forming the recess 24b, the description is omitted because it is known.

  FIG. 2 is a schematic plan view of the configuration of the liquid crystal display panel 200 according to the embodiment of the present invention. The arrangement of the spacers 15a and 15b and the recess 24b in the liquid crystal display panel 200 is different from the liquid crystal display panel 100 shown in FIG. 1, but the cross-sectional structure of the portion where the spacers 15a and 15b and the recess 24b are formed is the same as the liquid crystal display panel 100. Therefore, the sectional view is omitted. The arrangement of the spacers 15a and 15b and the recesses 24b shown here is merely an example, and can be appropriately changed according to the size of the liquid crystal display panel, the pixel size, and the application.

  In the liquid crystal display panel 200, the columnar structures 15a are provided for half of the B pixels 13B, and the columnar structures 15b and the recesses 24b are provided for half of the R pixels 13R. Further, the columnar structure 15a and the columnar structure 15b are provided in association with the B pixel 13B and the R pixel 13R adjacent to each other in the row direction. The columnar structures 15a and 15b associated with the G pixel are not provided. The columnar structures 15a and 15b provided in association with the B pixel 13B and the R pixel 13R are both arranged in the gap between the pixels in the pixel column arranged in a stripe pattern, and are provided on the TFT substrate. The circuit elements (for example, bus lines) 22 are shielded from light.

  Looking at a certain row, the B pixel 13B, the R pixel 13R, and the G pixel 13G are arranged cyclically. When one set of the pixels 13B, 13R, and 13G is one cycle, the columnar structures 15a and 15b are associated with each other. The formed pair of B pixel 13B and R pixel 13R appears every two periods. Even in rows adjacent in the column direction, pairs of the B pixel 13B and the R pixel 13R formed by associating the columnar structures 15a and 15b appear every two periods, but the phases are shifted by a half period. That is, the columnar structures 15a and 15b that are associated with the B pixel 13B and the R pixel 13R in the upper and lower columns of the B pixel 13B and the R pixel 13R that are formed in association with the columnar structures 15a and 15b in a certain row are provided. Not. Thus, the columnar structures 15a and 15b are uniformly arranged over the entire display area. The density of the columnar structures 15a and 15b in the display area of the liquid crystal display panel 200 is 1/6 on the basis of the number of pixels, and the total density of the columnar structures 15a and 15b is 1/3.

  Since the recess 24b is provided at a position facing the columnar structure 15b, only the columnar structures 15a having a number of 1/6 of the number of pixels function as spacers in a stationary state at room temperature. Further, when left standing at a low temperature (for example, −20 ° C.), the columnar structure 15a is elastically deformed following the decrease in volume of the liquid crystal material, thereby suppressing the generation of low-temperature bubbles. On the other hand, when an external force is applied to the display surface of the liquid crystal display panel, the columnar structure 15a is elastically deformed according to the external force. When the amount of deformation increases, the columnar structure 15b comes into contact with the TFT substrate 20 and exhibits a function as a spacer. That is, when an external force of a certain level or more is applied, not only the columnar structure 15a but also the columnar structure 15b functions as a spacer, so that the thickness of the liquid crystal layer is maintained or a predetermined thickness is achieved in a short time. Can return.

  The liquid crystal display panel 200 is, for example, 7.0 type, the pixel pitch is 65.0 μm in the row direction, 172.5 μm in the column direction, and the thickness of the liquid crystal layer 30 made of a nematic liquid crystal material having a negative dielectric anisotropy. In the case of a VA mode liquid crystal display panel having a thickness of about 4.5 μm, when the depth of the recess 24 b is about 0.3 μm and the diameter of the apex of the columnar columnar spacer 15 b is about 12.0 μm, low temperature bubbles are generated Was not seen. The columnar spacer was formed using a commercially available spacer material made of a photocurable resin.

  As described above, according to the embodiment of the present invention, a liquid crystal display panel having a structure in which the generation of low-temperature bubbles can be suppressed and a method for manufacturing the same can be provided.

  Here, a transmissive liquid crystal display panel is illustrated, but the present invention is not limited to this, and the present invention can also be applied to a reflective type or a transflective type (transmission / reflection type) liquid crystal display panel. In addition, a structure in which an electric field perpendicular to the liquid crystal layer surface is applied by a pair of electrodes (a pixel electrode and a counter electrode) arranged so as to face each other through the liquid crystal layer is illustrated. It can also be applied to generated configurations.

  The present invention is used for a liquid crystal display panel. In particular, it is suitably used for a liquid crystal display panel used in a display device that requires pressing resistance.

It is typical sectional drawing of the liquid crystal display panel 100 of embodiment by this invention. It is a typical top view of liquid crystal display panel 200 of an embodiment by the present invention.

Explanation of symbols

10 First substrate (color filter substrate)
DESCRIPTION OF SYMBOLS 11 Transparent substrate 12 Black matrix 13 Color filter layer 14 Counter electrode 15a, 15b Columnar spacer (columnar structure)
20 Second substrate (TFT substrate)
22 Circuit elements (eg TFT, wiring)
24 Insulating layer 24a Contact hole 24b Recessed part 26 Pixel electrode 30 Liquid crystal layer 100, 200 Liquid crystal display panel

Claims (9)

A liquid crystal display panel comprising a first substrate, a liquid crystal layer, and a second substrate disposed so as to face the first substrate through the liquid crystal layer, and having a display area including a plurality of pixels. ,
The first substrate has a plurality of columnar structures having substantially the same height provided at predetermined positions on the liquid crystal layer side,
The liquid crystal display panel, wherein the second substrate has a plurality of recesses at a position facing a preselected part of the plurality of columnar structures.   2. The columnar structure disposed at a position facing the plurality of recesses among the plurality of columnar structures is not in contact with the second substrate in a state where the columnar structure is allowed to stand at room temperature. LCD panel.   The liquid crystal display panel according to claim 1, wherein a depth of the plurality of recesses is 0.3 μm or more. The second substrate has a transparent substrate, a circuit element provided on the transparent substrate, and an insulating layer covering the circuit element,
The liquid crystal display panel according to claim 1, wherein the plurality of recesses are formed in the insulating layer.   The liquid crystal display panel according to claim 4, wherein the insulating layer is made of a photosensitive resin.   6. The liquid crystal display panel according to claim 1, wherein the plurality of recesses are provided in an outer peripheral portion of the plurality of pixels in the display region.   The liquid crystal display panel according to claim 1, wherein the first substrate has a counter electrode, and the plurality of columnar structures include a photosensitive resin layer formed on the counter electrode.   A display device comprising the liquid crystal display panel according to claim 1. A step (a) of preparing a first transparent substrate having a plurality of columnar structures having substantially the same height at a predetermined position determined in advance;
A step of preparing a second substrate having a plurality of recesses at a position facing a preselected part of the plurality of columnar structures when being bonded to the first substrate in a later step (c) ( b) and
A method of manufacturing a liquid crystal display panel, comprising a step (c) of bonding the first substrate and the second substrate through the plurality of columnar structures.

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