Patent Application
20110205473
The present invention relates to a liquid crystal display panel, and particularly relates to a liquid crystal display panel manufactured by using a vacuum injection method.
A liquid crystal display panel includes, e.g., a pair of substrates arranged so as to face each other, and a liquid crystal layer sealed between the pair of substrates. In order to manufacture such a liquid crystal display panel by using the vacuum injection method, e.g., sealing material is printed in a frame-like shape with a liquid crystal injection port on a surface of one of the substrates, and the one of the substrates and the other substrate are bonded together by the sealing material to provide a bonded body. Then, liquid crystal material is injected into the bonded body by using a pressure difference between an inside and an outside of the bonded body and a capillary action, and the liquid crystal injection port is sealed with UV curable resin.
For example, Patent Document 1 discloses a liquid crystal apparatus including a pair of first and second substrates arranged so as to face each other through sealing material, and liquid crystal sealed in a space surrounded by the first and second substrates and the sealing material. In the liquid crystal apparatus, a liquid crystal injection port through which the liquid crystal is injected is provided in the sealing material. In addition, raised sections configured to regulate a spacing between the pair of substrates are provided in a liquid crystal injection port region where the liquid crystal injection port is provided, and protrude from at least one of the pair of substrates toward the other substrate in a position where at least a part of the raised sections is stacked on the liquid crystal injection port region as viewed in plan. Further, the liquid crystal injection port is sealed with end sealing material. According to the liquid crystal apparatus, flexure due to contraction at the liquid crystal injection port can be reduced.
As illustrated in
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Top portions of the photo spacers 123a, 123b contact a surface of the TFT substrate 120, and are configured to maintain a thickness of the liquid crystal layer 140, i.e., a cell thickness. However, as illustrated in
The color filter layer 122 arranged in the display region D is typically formed by applying liquid photosensitive resin having a predetermined color. Thus, the color filter layer 122 is leveled and thinly formed on the relatively-thin grid-like black matrix 121 on which the photo spacers 123a are arranged. If the color filter layer is formed at the liquid crystal injection port M on the relatively-thick frame-like black matrix 121 (integrally-formed black matrix 121) on which the photo spacers 123b are arranged, the liquid photosensitive resin is not leveled, thereby thickly forming the color filter layer. This increases the cell thickness at the liquid crystal injection port M, and therefore the color filter layer cannot be arranged on the frame-like black matrix 121 on which the photo spacers 123b are arranged.
For the reasons above, the position of the top portion of the photo spacer 123b provided at the liquid crystal injection port M is lower than the position of the top portion of the photo spacer 123a provided in the display region D. As a result, it is likely that the cell thickness near the liquid crystal injection port M becomes non-uniform. In particular, in a liquid crystal display panel in which the liquid crystal injection port M is designed so as to have a large width in order to shorten an injection time of liquid crystal material, it is more likely that the cell thickness near the liquid crystal injection port M becomes non-uniform.
The present invention has been made in view of the foregoing, and it is an objective of the present invention to reduce a non-uniform cell thickness near a liquid crystal injection port.
In order to accomplish the foregoing objective, protrusions corresponding an under layer formed in the same layer as a part of a switching element and made of the same material as that of the part of the switching element are provided on a surface of an interlayer insulating film in the present invention.
Specifically, a liquid crystal display panel of the present invention includes an active matrix substrate and a color filter substrate arranged so as to face each other; a liquid crystal layer provided between the active matrix substrate and the color filter substrate; and sealing material provided to seal the liquid crystal layer between the active matrix substrate and the color filter substrate, and formed so as to have a liquid crystal injection port through which liquid crystal material forming the liquid crystal layer is injected. A display region where a plurality of pixels are arranged to display an image, and a frame region where the sealing material is applied around the display region are defined. The active matrix substrate includes switching elements each provided for each of the pixels, and an interlayer insulating film provided so as to cover the switching elements. The color filter substrate includes a black matrix provided in a frame-like shape in the frame region and provided in a grid pattern in the display region, a color filter layer provided so as to cover the black matrix in the display region, and columnar photo spacers provided so as to be stacked on the black matrix and contacting a surface of the active matrix substrate to maintain a thickness of the liquid crystal layer. The active matrix substrate further includes an under layer formed in the same layer as a part of the switching element and made of the same material as that of the part of the switching element, the under layer being stacked on the photo spacers arranged at the liquid crystal injection port. Protrusions corresponding to the under layer are provided on a surface of the interlayer insulating film.
According to the foregoing configuration, in a region of the active matrix substrate, where the liquid crystal injection port of the sealing material is arranged, the protrusions which protrude corresponding to the under layer formed in the same layer as a part of the switching element and made of the same material as that of the part of the switching element are provided on the surface of the interlayer insulating film covering the switching elements. Thus, even if, in the color filter substrate, a position of a top portion of the photo spacer provided so as to be stacked on the black matrix in a region of the frame region, where the liquid crystal injection port of the sealing material is arranged is lower than a position of a top portion of the photo spacer provided so as to be stacked on the black matrix of the display region by a thickness of the color filter layer, the top portion of the photo spacer can be in contact with the surface of the active matrix substrate or be closer to the surface of the active matrix substrate in the region where the liquid crystal injection port of the sealing material is arranged. This maintains the thickness of the liquid crystal layer not only in the display region but also in the region where the liquid crystal injection port of the sealing material is arranged. Thus, a non-uniform cell thickness in a portion near the liquid crystal injection port can be reduced.
Each of the switching elements may be a thin film transistor, and the under layer may include at least one of a first under layer formed in the same layer as a gate electrode of the thin film transistor and made of the same material as that of the gate electrode of the thin film transistor, a second under layer formed in the same layer as a semiconductor layer of the thin film transistor and made of the same material as that of the semiconductor layer of the thin film transistor, or a third under layer formed in the same layer as source and drain electrodes of the thin film transistor and made of the same material as that of the source and drain electrodes of the thin film transistor.
According to the foregoing configuration, the under layer includes at least one of the first under layer formed in the same layer as the gate electrode of the thin film transistor and made of the same material as that of the gate electrode of the thin film transistor, the second under layer formed in the same layer as the semiconductor layer of the thin film transistor and made of the same material as that of the semiconductor layer of the thin film transistor, or the third under layer formed in the same layer as the source and drain electrodes of the thin film transistor and made of the same material as that of the source and drain electrodes of the thin film transistor. Thus, the under layer can be specifically formed in the active matrix substrate without additional manufacturing steps.
The active matrix substrate may include a pixel electrode provided for each of the pixels on the interlayer insulating film. An upper layer is provided on the protrusion, and is formed in the same layer as the pixel electrode and made of the same material as that of the pixel electrode.
According to the foregoing configuration, the upper layer formed in the same layer as the pixel electrode and made of the same material as that of the pixel electrode is provided on the protrusion. Thus, in the active matrix substrate, the position of the top portion of the protrusion protruding corresponding to the under layer can be set to a higher level.
According to the present invention, the protrusions corresponding to the under layer formed in the same layer as a part of the switching element and made of the same material as that of the part of the switching element are provided on the surface of the interlayer insulating film. Thus, the non-uniform cell thickness in the portion near the liquid crystal injection port can be reduced.
a)-5(e) are cross-sectional views illustrating manufacturing steps of the TFT substrate 20a.
Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments below.
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The liquid crystal layer 40 is made of e.g., nematic liquid crystal material having electro-optical properties.
In the liquid crystal display panel 50a having the foregoing configuration, predetermined voltage is applied to the liquid crystal layer 40 arranged between each of the pixel electrodes 16a on the TFT substrate 20a and the common electrode on the CF substrate 30, for each pixel P, thereby changing an alignment state of the liquid crystal layer 40. Thus, a light transmittance through a panel is adjusted for each pixel P, thereby displaying the image.
Next, a method for manufacturing the liquid crystal display panel 50a of the present embodiment will be described with reference to
<Manufacturing of the TFT Substrate>
First, e.g., a titanium film, an aluminum film, and a titanium film are successively formed on an entire insulating substrate 10a such as a glass substrate by sputtering. Then, such films are patterned by photolithography, and therefore gate lines (not shown in the figure), gate electrodes 11a, and a first under layer 11b are formed in a thickness of about 0.2 μm as illustrated in
Subsequently, e.g., a silicon nitride film is formed on the entire substrate on which the gate lines, the gate electrodes 11a, the first under layer 11b are formed, by plasma CVD (chemical vapor deposition). A gate insulating film 12 is formed in a thickness of about 0.4 μm.
Further, an intrinsic amorphous silicon film and a phosphorus-doped n+amorphous silicon film are successively formed on the entire substrate on which the gate insulating film 12 is formed, by the plasma CVD. Then, such films are patterned in an island-like shape on the gate electrodes 11a and the first under layer 11b by the photolithography. As a result, as illustrated in
Then, e.g., an aluminum film and a titanium film are successively formed on the entire substrate on which the semiconductor layer 13a and the second under layer 13b are formed, by the sputtering. Subsequently, such films are patterned by the photolithography, and source lines (not shown in the figure), source electrodes 14a, drain electrodes 14b, and a third under layer 14c are formed in a thickness of about 0.35 μm as illustrated in
Subsequently, the n+amorphous silicon layer of the semiconductor layer 13a is etched by using the source electrodes 14a and the drain electrodes 14b as a mask, and channel portions are patterned to form TFTs 5.
Then, e.g., an inorganic insulating film such as a silicon nitride film is formed in a thickness of about 0.3 μm on the entire substrate on which the TFTs 5 are formed, by the plasma CVD, followed by applying, e.g., acrylic photosensitive resin so as to have a thickness of about 2.5 μm by spin coating. Subsequently, the applied photosensitive resin is exposed to light and developed through a photo mask, thereby forming an organic insulating film in which contact holes are patterned on the drain electrodes 14b. Then, the inorganic insulating film exposed under the organic insulating film is etched to form the contact holes, thereby forming an interlayer insulating film 15 as illustrated in
An ITO (indium tin oxide) film is formed on the entire substrate on which the interlayer insulating film 15 is formed, by the sputtering. Subsequently, such a film is patterned by the photolithography, and pixel electrodes 16a are formed in a thickness of about 0.1 μm as illustrated in
Finally, polyimide resin is applied to the entire substrate on which the pixel electrodes 16a are formed, by printing. Subsequently, a rubbing process is performed, thereby forming an alignment film in a thickness of about 0.1 μm.
In the manner described above, a TFT substrate 20a can be manufactured.
<Manufacturing of the CF Substrate>
First, e.g., acrylic photosensitive resin in which particulates such as carbon are dispersed is applied to an entire insulating substrate 10b such as a glass substrate by the spin coating. Then, the applied photosensitive resin is exposed to light through a photo mask, and is developed. As a result, a black matrix 21 is formed in a thickness of about 1.5 μm.
Subsequently, e.g., acrylic photosensitive resin colored red, green, or blue is applied to the substrate on which the black matrix 21 is formed. For patterning, the applied photosensitive resin is exposed to light through the photo mask and is developed. Then, a colored layer having a selected color (e.g., a red-colored layer) is formed in a thickness of about 2.0 μm. Further, the similar process is repeated for other two colors. Colored layers having the other two colors (e.g., a green-colored layer and a blue-colored layer) are formed in a thickness of about 2.0 μm, thereby forming a color filter layer 22.
Then, e.g., an ITO film is formed on the substrate on which the color filter layer 22 is formed, by the sputtering, thereby forming a common electrode in a thickness of about 1.5 μm.
Subsequently, photosensitive resin is applied to the entire substrate on which the common electrode is formed, by the spin coating. The applied photosensitive resin is exposed to light through the photo mask and is developed, thereby forming photo spacers 23a, 23b in a thickness of about 4 μm.
Finally, polyimide resin is applied to the entire substrate on which the photo spacers 23a, 23b are formed, by the printing. Then, the rubbing process is performed, thereby forming an alignment film in a thickness of about 0.1 μm.
In the manner described above, a CF substrate 30 can be manufactured.
<Injection of Liquid Crystal>
First, sealing material 41 made of thermoset resin is applied to a frame region F of the CF substrate 30 manufactured in the manufacturing of the CF substrate, by the printing.
Subsequently, the CF substrate 30 to which the sealing material 41 is applied, and the TFT substrate 20a manufactured in the manufacturing of the TFT substrate are bonded together. Then, such substrates are heated in order to cure the sealing material 41 between the TFT substrate 20a and the CF substrate 30.
Further, liquid crystal material is injected between the TFT substrate 20a and the CF substrate 30 of the bonded body in which the sealing material 41 is cured, through a liquid crystal injection port M by a vacuum injection method. Then, the liquid crystal injection port M is sealed with end sealing material 42 made of UV curable resin, thereby forming a liquid crystal layer 40.
In the manner described above, a liquid crystal display panel 50a of the present embodiment can be manufactured.
As described above, according to the liquid crystal display panel 50a of the present embodiment, in a region of the TFT substrate 20a, where the liquid crystal injection port M of the sealing material 41 is arranged, the protrusions T which protrude corresponding to the under layer U including the first under layer 11b, the second under layer 13b, and the third under layer 14c which are formed in the same layer as the gate electrode 11a, the semiconductor layer 13a, the source electrode 14a, and the drain electrode 14b of the TFT 5 and are made of the same material as those of gate electrode 11a, the semiconductor layer 13a, the source electrode 14a, and the drain electrode 14b of the TFT 5 are provided on the surface of the interlayer insulating film 15 covering the TFTs 5. Thus, even if, in the CF substrate 30, the position of the top portion of the photo spacer 23b provided so as to be stacked on the black matrix 21 in the region of the frame region F, where the liquid crystal injection port M of the sealing material 41 is arranged is lower than the position of the top portion of the photo spacer 23a provided so as to be stacked on the black matrix 21 of the display region D by the thickness of the color filter layer 22, the top portion of the photo spacer 23b can be in contact with the surface of the TFT substrate 20a or be closer to the surface of the TFT substrate 20a in the region where the liquid crystal injection port M of the sealing material 41 is arranged. This maintains the thickness of the liquid crystal layer 40 not only in the display region D but also in the region where the liquid crystal injection port M of the sealing material 41 is arranged. Thus, the non-uniform cell thickness in the portion near the liquid crystal injection port M can be reduced without additional manufacturing steps.
In the liquid crystal display panel 50a of the first embodiment, the under layer U has the three-layer structure of the first under layer 11b, the second under layer 13b, and the third under layer 14c. However, in the liquid crystal display panels 50b, 50e of the present embodiment, an under layer U has a single-layer structure.
Specifically, as illustrated in
In addition, as illustrated in
The liquid crystal display panel 50b having the foregoing configuration can be manufactured by the manufacturing method described in the first embodiment, in which the formation of the second under layer 13b and the third under layer 14c is skipped. In addition, the liquid crystal display panel 50c having the foregoing configuration can be manufactured by the manufacturing method described in the first embodiment, in which the formation of the first under layer 11b and the second under layer 13b is skipped.
According to the liquid crystal display panels 50b, 50c of the present embodiment, protrusions T corresponding to the under layer U formed in the same layer as a part of a TFT 5 and made of the same material as that of the part of the TFT 5 are provided on a surface of an interlayer insulating film 15 as in the first embodiment. Thus, a non-uniform cell thickness in a portion near a liquid crystal injection port M can be reduced without additional manufacturing steps.
In the present embodiment, the example has been described, in which the under layer U includes the single layer which is the first under layer 11b or the third under layer 14c of the first embodiment. However, the under layer U may include a single layer which is the second under layer 13b of the first embodiment.
In the liquid crystal display panel 50a of the first embodiment, the under layer U has the three-layer structure of the first under layer 11b, the second under layer 13b, and the third under layer 14c, and, in the liquid crystal display panels 50b, 50c of the second embodiment, the under layer U has the single-layer structure. However, in the liquid crystal display panel 50d of the present embodiment, an under layer U has a double-layer structure.
Specifically, as illustrated in
The liquid crystal display panel 50d can be manufactured by the manufacturing method described in the first embodiment, in which the formation of the second under layer 13b is skipped.
According to the liquid crystal display panel 50d of the present embodiment, protrusions T corresponding to the under layer U formed in the same layer as a part of a TFT 5 and made of the same material as that of the part of the TFT 5 are provided on a surface of an interlayer insulating film 15 as in the first and second embodiments. Thus, a non-uniform cell thickness in a portion near a liquid crystal injection port M can be reduced.
In the present embodiment, the example has been described, in which the under layer U includes the two layers which are the first under layer 11b and the third under layer 14c of the first embodiment. However, the under layer U may include two layers which are the first under layer 11b and the second under layer 13b of the first embodiment, or the second under layer 13b and the third under layer 14c of the first embodiment.
In the liquid crystal display panels 50a-50d of the first to third embodiments, the protrusions T are formed corresponding to the under layer U. However, in the liquid crystal display panel 50e of the present embodiment, each of protrusions T includes an upper layer 16b.
Specifically, as illustrated in
The liquid crystal display panel 50e having the foregoing configuration can be manufactured by the manufacturing method described in the first embodiment, in which a pattern shape when etching an ITO film forming the pixel electrode 16a is changed as necessary.
According to the liquid crystal display panel 50e of the present embodiment, the protrusions T corresponding to the under layer U formed in the same layer as a part of a TFT 5 and made of the same material as that of the part of the TFT 5 are provided on a surface of an interlayer insulating film 15 as in the first to third embodiments. Thus, a non-uniform cell thickness in a portion near a liquid crystal injection port M can be reduced without additional manufacturing steps. In addition, the upper layer 16b formed in the same layer as the pixel electrode 16a and made of the same material as that of the pixel electrode 16a is provided on the protrusion T. Thus, in the TFT substrate 20e, a position of the top portion of the protrusion T protruding corresponding to the under layer U can be set to a higher level.
In the present embodiment, the example has been described, in which the upper layer 16b is stacked on the under layer U of the first embodiment. However, a configuration may be applied, in which the upper layer 16b is stacked on each of the under layers U of the second and third embodiments.
In the foregoing embodiments, the TFT is described as an example of a switching element. However, the present invention may be applied to other switching elements such as MIM (metal insulator metal).
As described above, the present invention reduces the non-uniform cell thickness in the portion near the liquid crystal injection port, and therefore is useful for the liquid crystal display panel manufactured by using the vacuum injection method.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-003864 | Jan 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/003742 | 8/5/2009 | WO | 00 | 4/27/2011 |
