Patent Application
20170329177
The present invention relates to a liquid crystal display panel, a liquid crystal display apparatus comprising the liquid crystal display panel, and a method of manufacturing the liquid crystal display panel.
In recent years, a liquid crystal display panel employed in many display apparatuses has a configuration in which a pair of substrates are opposed with a predetermined interval, and liquid crystal is filled therebetween. On one substrate, a picture element electrode for applying a voltage to the liquid crystal, a switching element such as a thin film transistor for driving the picture element electrode, various wirings such as a gate bus line and a source bus line, an alignment film for applying a pretilt angle to the liquid crystal, and the like, are formed in a laminated shape. In addition, on the other substrate, a black matrix, a color filter layer of a predetermined color, a counter electrode, an alignment film, and the like, are formed in a similarly laminated shape.
The black matrix and the color filter layer are formed by using a photolithographic method. For example, the black matrix is formed through a process of applying a black photoresist material to a surface of the substrate, an exposure process of irradiating a predetermined pattern region of the photoresist material with a light energy through a photo mask, and a process of removing an unnecessary portion of the photoresist material (a portion which is not irradiated with the light energy).
In forming the black matrix as described above, the photo mask is used. Since an accuracy of the formed black matrix depends on an accuracy of the photo mask, a high processing accuracy is required for the photo mask. Meanwhile, in recent years, with an increase in size of the substrate, a size of the photo mask also increases, and a size of an exposure device needs to be increased, thereby causing an increase in manufacturing cost.
To cope with such a situation, instead of exposing the entire substrate at one time in the exposure process, a divided exposure method of dividing the substrate into several regions to expose the substrate is employed. In the divided exposure method, there is a need to splice patterns of adjacent regions with each other. Therefore, the exposure is performed on the adjacent portions twice to splice the patterns. However, if the patterns are spliced in a well-defined rectangle shape, splicing unevenness is seen. Thereby, a method of providing a certain degree of width to the splicing part, and splicing the patterns in a mosaic pattern is generally used. The mosaic pattern is a pattern in which a density of presence or absence of the pattern is changed, and means a pattern which is set so as to change the density of the pattern from dense to coarse as it is separated from its own exposure pattern. However, if the pattern is too thick in order to change the density, an effect of the mosaic pattern is diminished, and then the splicing part is divided within one picture element (Japanese Patent Laid-open Publication No. 2000-66235). Be noted that the picture element means a single-color portion constituting one pixel. Generally, three picture elements of red, green and blue constitute one pixel.
In addition, the photo mask is positionally shifted in directions opposite to each other during the first and second exposures, and thereby it is necessary to thicken the pattern so as to prevent a slit (gap) from being generated in the formed pattern.
Further, in forming the color filter, it is also necessary to consider the positional shift when coloring the picture element after forming the black matrix. The reason is that, a gap is formed between a colored portion and the black matrix, such that a problem of a so-called void in which light is leaked therefrom occurs. From the viewpoint of preventing the void, it is necessary to thicken the black matrix.
As described above, in the conventional art, since the pattern of the splicing part is thickened, there is a problem of a reduction in aperture ratio. In recent years, a definition of the liquid crystal display panel is increased and a size of one pixel thereof is decreased. That is, the number of pixels included in one liquid crystal display panel is increased, and as a result, there is a problem that an area occupied by the black matrix is also increased, and thereby the aperture ratio is reduced.
In consideration of the above-mentioned circumstances, it is an object of the present disclosure to provide a liquid crystal display panel, and the like that suppresses a reduction in aperture ratio even in a liquid crystal display panel having high definition.
The liquid crystal display panel according to the present disclosure is a liquid crystal display panel comprising two opposing substrates provided with liquid crystal sealed therebetween, wherein on one substrate a plurality of colored parts are arranged so as to constitute one pixel, and a plurality of boundary regions are arranged between a plurality of adjacent colored parts and around the plurality of colored parts, and wherein the boundary region arranged between adjacent colored parts has a width smaller than that of the boundary region arranged around the plurality of colored parts.
According to the present disclosure, the boundary region arranged between adjacent colored parts has a width smaller than that of the boundary region arranged around the plurality of colored parts. That is, since the boundary region in the portion on which the screen splicing is not performed is thinner than the boundary region on which the screen splicing is performed, it is possible to suppress a reduction in aperture ratio even in a liquid crystal display panel having high definition.
The liquid crystal display panel according to the present disclosure is characterized in that a plurality of the boundary regions arranged around the plurality of colored parts are arranged at a constant interval.
According to the present disclosure, the plurality of boundary regions arranged around the plurality of colored parts are arranged at a constant interval. That is, since the boundary regions on which the screen splicing is performed are arranged at a constant interval, it is possible to suppress a reduction in aperture ratio even in a liquid crystal display panel having high definition.
The liquid crystal display panel according to the present disclosure is characterized in that the plurality of the boundary regions arranged around the plurality of colored parts are arranged between adjacent pixels.
According to the present disclosure, the plurality of the boundary regions arranged around the plurality of colored parts are arranged between the adjacent pixels. That is, by constituting a mask pattern in a pixel unit, the mask pattern can be used for manufacturing a plurality of liquid crystal display panels having different numbers of pixels from each other.
The liquid crystal display apparatus according to the present disclosure is a liquid crystal display apparatus comprising the above-described liquid crystal display panel as a display section.
According to the present disclosure, it is possible to achieve a display apparatus comprising a liquid crystal display panel having high definition while suppressing a reduction in aperture ratio.
The method of manufacturing a liquid crystal display panel according to the present disclosure is a method of manufacturing a liquid crystal display panel, comprising: preparing a photo mask provided with linear patterns at positions corresponding to boundary regions between a plurality of adjacent colored parts and around the plurality of colored parts, the liner pattern in a portion corresponding to the boundary region between adjacent colored parts having a width smaller than that of the liner pattern in a portion corresponding to the boundary region around the plurality of colored parts; sequentially performing exposure on one substrate by photolithography using the photo mask so that the colored parts are arranged in a matrix to form lattice-shaped boundary regions; adding colors inside lattices formed by the boundary regions to form a plurality of colored parts so as to constitute respective pixels each including a plurality of colored parts; and opposing the one substrate and the other substrate, and then sealing liquid crystal therebetween.
According to the present disclosure, since boundary regions (black matrix) are formed by using the photo mask in which the liner pattern in a portion corresponding to the boundary region between adjacent colored parts has the width smaller than that of the liner pattern in a portion corresponding to the boundary region around a plurality of colored parts, it is possible to manufacture a liquid crystal display panel having high definition while suppressing a reduction in aperture ratio.
The method of manufacturing a liquid crystal display panel according to the present disclosure is a method of manufacturing a liquid crystal display panel, comprising: preparing a photo mask provided with linear patterns at positions corresponding to boundary regions between a plurality of adjacent colored parts and around the plurality of colored parts, the liner pattern in a portion corresponding to the boundary region between adjacent colored parts having a width smaller than that of the liner pattern in a portion corresponding to the boundary region around the plurality of colored parts, the photo mask being capable of simultaneously forming boundary regions corresponding to a plurality of pixels each including a plurality of colored parts; sequentially performing exposure on one substrate by photolithography using the photo mask so that the pixels are arranged in a matrix to form lattice-shaped boundary regions; adding colors inside lattices formed by the boundary regions to form a plurality of colored parts so as to constitute respective pixels; and opposing the one substrate and the other substrate, and then sealing liquid crystal therebetween.
According to the present disclosure, since the photo mask capable of simultaneously forming boundary regions corresponding to a plurality of pixels is used, it is possible to reduce the number of times of exposure for forming the boundary regions (black matrix).
In the present disclosure, it is possible to secure an aperture ratio in a liquid crystal display panel having high definition.
The above and further objects and features will more fully be apparent from the following detailed description with accompanying drawings.
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings illustrating embodiments thereof.
The polarizing plates 11 and 20 are adapted to polarize light incident thereon or emitted therefrom in a specific direction. Light passing through the polarizing plate 11 and light passing through the polarizing plate 20 have different polarization directions by 90 degrees. The transparent substrate 12 is, for example, a rectangular plate made of glass. The color filter layer 13 includes a black matrix 131 (boundary region) and a color filter 132 (colored part). The color filter layer 13 is formed on the transparent substrate 12. The transparent electrodes 14 and 18 and the alignment films 15 and 17 control an alignment of liquid crystal contained in the liquid crystal layer 16. The transparent substrate 19 is formed of: inorganic glass such as quartz glass, borosilicate glass, soda glass; a substrate made of plastic such as polyethylene terephthalate (PET), polyethersulfone (PES), polycarbonate (PC); an inorganic thin film such as silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride formed on a surface of the glass or the plastic substrate or the like. The backlight 21 converts light from a light source 211 such as a light emitting diode (LED) into planar light and irradiates the polarizing plate 20 with the planar light. The remaining portion of the liquid crystal display apparatus 10 except for the backlight 21 (including the light source 211) is referred to as a liquid crystal display panel.
Next, a process of forming a black matrix will be described. In forming the black matrix, a screen splicing exposure method is employed. The screen splicing exposure method is a method in which a pattern required to form a black matrix in one transparent substrate is divided into two or more divided patterns, and the divided patterns are formed on photo masks, and these divided patterns are transferred to adjacent regions on the transparent substrate to couple images of the divided patterns with each other (screen splicing) on the transparent substrate, such that a transparent substrate having a large area can be formed even in an exposure device with a small exposure field or image field.
In manufacturing the liquid crystal display panel, the transparent substrate 12 on which the color filters 132 are formed and the transparent substrate 19 are bonded so as to face each other. After the transparent substrate 12 and the transparent substrate 19 are bonded to each other, liquid crystal is injected and sealed therebetween. Further, the polarizing plates 11 and 20 are attached to the transparent substrates 12 and 19, respectively, and assembly of the liquid crystal display panel is completed. Then, the separately assembled backlight 21 is combined with the liquid crystal display panel, thereby completing the liquid crystal display apparatus 10.
Subsequently, the photo mask 30 used in an exposure process will be described. The photo mask 30 includes a photo mask substrate 31 and a light shielding film 32. The photo mask substrate 31 is a substrate which is made of, for example, synthetic quartz, soda-lime glass, alkali-free glass, or the like, and is transparent with respect to exposure light. The light shielding film 32 shields the exposure light during the exposure process. The light shielding film 32 is formed on the photo mask substrate 31 by, for example, a chromium (Cr)-based material. The light shielding film 32 is, for example, a CrN film, a CrC film, a CrCO film, a CrO film, a CrON film, or a laminated film thereof.
The first mask pattern 1 (second mask pattern 2) is formed in a rectangular shape, and three identical rectangular window parts 1a (2a) are formed side by side in a lateral direction in the first mask pattern 1 (second mask pattern 2). The window parts 1a (2a) are portions where color layers are formed. In the first mask pattern 1 (2), it is possible to form a black matrix for three picture elements (RGB), that is, for one pixel. Each picture element has a size in a longitudinal direction longer than a size in the lateral direction. As illustrated in
The mosaic pattern used for mosaic splicing in Embodiment 1 will be described. Hereinafter, a black matrix in Ultra High Definition (UHD) is applied to Embodiment 1. An object to be compared is a black matrix with Full High Definition (FHD) resolution formed by the conventional art. Similar to the conventional art, also in Embodiment 1, the mosaic pattern used for mosaic splicing includes a plurality of dots. In Embodiment 1, a longitudinal width of the dots constituting the mosaic pattern is 1/2 as compared to the conventional art. In addition, a lateral width of the dots is 3/2 as compared to the conventional art. Thereby, a size (area) of the dots is 3/4 of the conventional dot. As such, even when the mosaic splicing is performed for each one pixel formed by combining a plurality of picture elements in QFHD, the size of the mosaic is smaller than that of the conventional mosaic, and the fineness is therefore improved as compared to the conventional FHD.
As described above, in Embodiment 1, the black matrix for one pixel is formed by one exposure. Therefore, there is no mosaic splicing of the black matrix within one pixel. Accordingly, a positional shift causing a void does not occur, such that it is possible to decrease a width of the black matrix. Thereby, it is possible to secure a sufficient aperture ratio.
In addition, since the size of the dots constituting the mosaic pattern is decreased, it is possible to improve the fineness of the liquid crystal display panel.
In the modified example, the exposure of the black matrix for two pixels is performed with one mask pattern, and it is therefore possible to complement the width of the black matrix between two pixels adjacent to each other formed by simultaneously exposing, and secure a sufficient aperture ratio.
In the modified example, the black matrix for two pixels is simultaneously exposed, but it is not limited thereto, and a black matrix for three pixels or more may be simultaneously exposed. In a case of higher definition such as 8K4K resolution, the number of pixels to be simultaneously exposed is increased, and it is therefore possible to improve the fineness of the liquid crystal display panel.
Embodiment 2 is an embodiment about a mask pattern allowing exposure of a black matrix for two pixels with each mask pattern and for four pixels with two mask patterns, respectively.
As described above, in Embodiment 2, in addition to the effects produced in Embodiment 1, the following effects are produced. Since the colors of the adjacent picture elements of the pixels adjacent to each other in the lateral direction are the same as each other, it is not necessary to increase the width of the black matrix in order to cope with the positional shift in a coloring process of the picture element. Therefore, it is possible to further decrease the width (d11) of the black matrix of pixels adjacent to each other in the lateral direction with respect to the width (d1) in Embodiment 1, and to increase the aperture ratio.
In Embodiment 3, a black matrix for two pixels adjacent to each other in the lateral direction (a direction along a short side of the picture element) is formed.
In Embodiment 3, since the black matrix for two pixels adjacent to each other in the lateral direction is simultaneously formed, there is no need to splice the black matrix between the adjacent pixels. Therefore, as illustrated in
Be noted that the black matrix extending laterally needs to have a width within a certain degree. A domain in the vicinity of a bus line on a thin film transistor (TFT) side formed in the transparent substrate 19 becomes a liquid crystal misaligned place. If there is the liquid crystal misaligned place, the domain will not turn black even when displaying black, such that a decrease in a contrast occurs. In order to shield the liquid crystal misaligned place, it is necessary to secure the width of the black matrix within a certain degree.
Further, in the above-described embodiments, a method of bonding a color filter (CF) substrate and a TFT substrate as a configuration of the liquid crystal display panel is assumed, but it is not limited thereto. It is also possible to apply to a liquid crystal display panel having a CF on array (COA) structure in which the colored layer is formed on the TFT substrate side.
In Embodiments 1 to 3, the mask pattern that can form the black matrix in one pixel (three picture elements) unit is employed, but it is not limited thereto. A mask pattern that can form two or four or more adjacent picture elements as one unit may be employed. In that case, it is possible to decrease the width of the black matrix between a plurality of picture elements constituting one unit.
Be noted that, in
Technical characteristics (configuration requirements) described in each embodiment may be combined with each other, and new technical characteristics may be formed by combining the same. It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. Since the scope of the present invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.
It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
This application is the national phase under 35 U. S. C. §371 of PCT International Application No. PCT/JP2014/081572 which has an International filing date of Nov. 28, 2014 and designated the United States of America.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2014/081572 | 11/28/2014 | WO | 00 |
