Patent Application
20150153596
The present invention relates to a display panel, such as a liquid crystal display panel in which a pair of substrates are stacked together with a prescribed gap therebetween and liquid crystal is sealed in the gap.
In recent years, there has been demand for thinner and smaller display panels, such as liquid crystal display panels, following the rapid rise of mobile devices equipped with these display panels, such as notebooks computers and mobile phones.
A liquid crystal display panel typically includes a pair of substrates arranged facing each other (namely, a TFT (thin film transistor) substrate and a CF (color filter) substrate), a liquid crystal layer provided between these substrates, and a frame-shaped sealing member that adheres the substrates together and seals the liquid crystal between the substrates.
This type of liquid crystal display panel is used in mobile devices such as mobile phones, portable information terminal devices, portable gaming devices, and the like. There is particularly aggressive demand for the pixel areas in the liquid crystal display panel to be expanded, from the viewpoint of ease of carrying the mobile device and for the mobile device to be smaller and thinner. Accordingly, to achieve this type of pixel area expansion of the liquid crystal display panel, it is necessary for the portion outside the display area of the liquid crystal display panel (in other words, the frame region) to be able to be made as narrow as possible. This means that the frame region of the liquid crystal display panel must be made narrower.
To achieve a narrower frame region, the width of the sealing member disposed on the frame region needs to be reduced, but this decreases the adhesive area of the sealing member, thus lowering the adhesive strength and the bulk strength of the sealing member.
The most efficient method of forming the sealing member is for the sealing member to have the same width around the display area, which means that the portion of the sealing member on the wide frame region adjacent to the terminal region has the same width as the portion of the sealing member on the narrow frame regions.
The only member disposed in the terminal region, however, is the glass substrate that forms a portion of the TFT substrate. Therefore, if the sealing member is formed at the same width throughout, then when external stress is exerted on the terminal region and causes the portion of the substrate at the terminal region to warp, stress will be exerted on the portion of the sealing member in the wide frame region adjacent to the terminal region. This results in the base film of the sealing member peeling off.
If the width of the sealing member is reduced, the bulk strength thereof will be lowered. Thus, when the sealing member is hardened after the pair of substrates are bonded together, the sealed liquid crystal will leak through the sealing member to outside. This results in bubbles (voids) in the display area and causes display defects.
If the width of the sealing member is reduced, secondary stress exerted on the lower layer film of the sealing member will increase, thus causing the lower layer film on the TFT substrate side and the CF substrate side to peel off.
As a countermeasure, a liquid crystal display panel in which the adhesive strength of the sealing member is improved by providing a plurality of sealing members is proposed.
More specifically, a liquid crystal display panel is described as having sealing members that twice surround the display area on the frame region of the liquid crystal display panel. It is described that this type of configuration makes it possible to improve the adhesive strength of the sealing members and to improve the yield of manufacturing high-quality liquid crystal display panels (see Patent Document 1, for example).
In general, however, the narrowness of the narrow frame region on the liquid crystal display panel makes it very difficult to form the sealing members twice surrounding the display area, as described in Patent Document 1 with respect to the liquid crystal display panel. Furthermore, if the sealing members are indeed formed to twice surround the display area, this leads to an increase in manufacturing steps.
The present invention was made in view of the above-mentioned problems, and aims at providing a display panel that can have a narrow frame region while avoiding a decrease in adhesive strength of the sealing member, and without increasing the number of manufacturing steps.
To achieve the above-mentioned aims, a display panel of the present invention includes: a first substrate; a second substrate facing the first substrate; a display element provided between the first substrate and the second substrate; a terminal region defined along one side of the first substrate; a display area where an image is displayed; a frame region defined around the display area, the frame region being constituted of a first frame region next to the terminal region and second frame regions that are narrower than the first frame region; and a sealing member disposed on the frame region and sandwiched between the first substrate and the second substrate to attach the first substrate to the second substrate, wherein a width of the sealing member in the second frame regions of the frame region is less than a width of the sealing member in the first frame region, and wherein end faces of the sealing member in the respective second frame regions are arranged so as to be aligned with corresponding end faces of the display panel in a plan view.
With this configuration, even if the wide sealing member is formed on the cutting line of the display panel in the second frame regions in the step of forming the sealing member, it is possible to cut the sealing member along this cutting line in the step of cutting to produce an optimum width, thereby making it possible to obtain a width of the sealing member that is sufficient to ensure adhesive strength in the second frame regions, which are narrow. Furthermore, an optimum width of the sealing member can also be obtained in the first frame region, which is wide, on the terminal region side in the step of forming the sealing member, after which this portion of the sealing member is not cut and can remain wider than the portion of the sealing member in the second frame regions. Accordingly, unlike in the conventional technology described above, this narrow-framed liquid crystal display panel can prevent a decrease in adhesive strength of the sealing member without increasing the number of manufacturing steps.
According to one aspect of the display panel of the present invention, the first substrate and the second substrate each further include a planarizing film disposed in the frame region on a side adjacent to the sealing member, the sealing member is formed on the planarizing films and further includes spacers disposed therein for defining a gap between the first substrate and the second substrate in the frame region, and a distance from the display area to the first frame region of the frame region is equal to a distance from the display area to the respective sealing member in the second frame regions of the frame region.
With this configuration, even if there is a difference in film thickness in the first frame region and the second frame regions, the heights of the sealing member on the display area side can be equal to each other, thus making it possible to prevent deviations in height of the sealing member in the first frame region and the second frame regions. Accordingly, the spacers can make the cell gap in the first frame region (the distance between the first substrate and the second substrate) match the cell gap in the second frame regions, and thus preventing variations in the cell gap in the entire display device.
According to one aspect of the display panel of the present invention, the width of the sealing member in the first frame region of the frame region is 0.4 mm to 1.6 mm and the width of the sealing member in the second frame regions of the frame region is 0.2 mm to 0.8 mm.
The display panel of the present invention has excellent characteristics, or namely, making it possible to provide a narrow-framed display panel that can prevent a reduction in adhesive strength of the sealing member without increasing the number of manufacturing steps. Accordingly, the present invention can be suitably used when the display panel has a display element that is a liquid crystal display element, or a display element that is an organic electroluminescent display element.
In the present invention, a method of manufacturing a first substrate, a second substrate facing the first substrate, a display element provided between the first substrate and the second substrate, a terminal region defined along one side of the first substrate, a display area where an image is displayed, a frame region defined around the display area, the frame region being constituted of a first frame region next to the terminal region and second frame regions that are narrower than the first frame region, and a sealing member disposed on the frame region and sandwiched between the first substrate and the second substrate to attach the first substrate to the second substrate, at least includes: fabricating a first mother substrate having a plurality of the first substrates formed thereon and a second mother substrate having a plurality of the second substrates formed thereon; forming the frame-shaped sealing member on each of the frame regions of the respective first substrates, the frame-shaped sealing member is formed so as to straddle respective cutting lines for the first substrate defined in the first mother substrate on the second frame regions on the respective first substrates; bonding the first mother substrate and the second mother substrate via the sealing members such that the cutting lines for the respective first substrates are aligned with cutting lines defined in the second mother substrate for separating the second substrates from the second mother substrate, and such that the sealing members respectively straddle the cutting lines for separating the second substrates, thereby forming a bonded member, and cutting the bonded member and each of the sealing members along the respective cutting lines for the first substrates and the respective cutting lines for the second substrates in the second frame regions so as to form sealing members that are narrower than the sealing members on the respective first frame regions.
With this configuration, even if the wide sealing member is formed on the cutting line of the display panel in the second frame regions in the step of forming the sealing member, it is possible to cut the sealing member along this cutting line in the step of cutting to produce an optimum width, thereby making it possible to obtain a width of the sealing member that is sufficient to ensure adhesive strength in the second frame regions, which are narrow. Furthermore, an optimum width of the sealing member can also be obtained in the first frame region, which is wide, on the terminal region side in the step of forming the sealing member, after which this portion of the sealing member is not cut and can remain wider than the portion of the sealing member in the second frame regions. Accordingly, unlike in the conventional technology described above, this narrow-framed liquid crystal display panel can prevent a decrease in adhesive strength of the sealing member without increasing the number of manufacturing steps.
According to the method of manufacturing a display panel of the present invention, in the step of fabricating the mother substrates, planarizing films are respectively formed on the first substrates and the second substrates, and in the step of forming the sealing members, each of the sealing members contains spacers for defining gaps between the respective first substrates and the second substrates in the frame region, and the sealing members are formed on the respective planarizing films such that a distance from the display area to the sealing member in the first frame region of the frame region is equal to a distance from the display area to the sealing member in each of the second frame regions of the frame region.
With this configuration, even if there is a difference in film thickness in the first frame region and the second frame regions, the heights of the sealing member on the display area side can be equal to each other, thus making it possible to prevent deviations in height of the sealing member in the first frame region and the second frame regions. Accordingly, the spacers can make the cell gap in the first frame region (the distance between the first substrate and the second substrate) match the cell gap in the second frame regions, and thus preventing variations in the cell gap in the entire display device.
According to the method of manufacturing a display panel of the present invention, in the step of cutting, a super steel wheel is used to cut the bonded member and the sealing members.
The display panel of the present invention has excellent characteristics, or namely, making it possible to provide a narrow-framed display panel that can prevent a reduction in adhesive strength of the sealing member without increasing the number of manufacturing steps. Accordingly, the method of manufacturing a display panel of the present invention can be applied when the display element is a liquid crystal display element, or the when the display element is an organic electroluminescent display element.
According to the present invention, it is possible to provide a display panel that that can have a narrow frame region while avoiding a decrease in adhesive strength of the sealing member, and without increasing the number of manufacturing steps.
Embodiments of the present invention will be described in detail below with reference to drawings. The present invention is not limited to the embodiments below.
As shown in
This sealing member 26 is formed so as to surround the liquid crystal layer 25, and the TFT substrate 10 and the CF substrate 20 are bonded to each other through this sealing member 26.
As shown in
The terminal region T of the liquid crystal display panel 1 is defined along one side (a top Ef) of the TFT substrate 10, and the terminal region T has a so-called “three-side-free structure,” in which the terminal region is disposed only on the one side mentioned above.
In the liquid crystal display panel 1, a display area D, which is where image display is performed, is defined by an area where the TFT substrate 10 and the CF substrate 20 overlap. A plurality of pixels, which are the smallest units of an image, are arranged in a matrix in the display area D.
A four-sided frame region, which is where the sealing member 26 is disposed, is defined around the display area D, and as shown in
The TFT substrate 10 includes a plurality of gate lines (not shown) arranged so as to extend in parallel to each other on an insulating substrate such as a glass substrate or a plastic substrate, a gate insulating film (not shown) covering the gate lines, and a plurality of source lines (not shown) arranged on the gate insulating film so as to extend in parallel to each other in a direction intersecting the respective gate lines, for example. The TFT substrate 10 also includes a plurality of TFTs (not shown), with one TFT being disposed at each intersection of the respective gate lines and source lines (in other words, one TFT for each pixel), a planarizing film covering the TFTs and source lines, a plurality of pixel electrodes (not shown) arranged in a matrix on the planarizing film and connected to the respective TFTs, and an alignment film (not shown) covering the pixel electrodes.
The CF substrate 20 includes a frame-shaped black matrix (not shown) disposed on an insulating substrate such as a glass substrate or plastic substrate in a grid pattern as a light-shielding member, and a color filter (not shown) having red portions, green portions, blue portions, or the like arranged so as to correspond to the black matrix grid, for example. The CF substrate 20 also includes a planarizing film (not shown) covering the black matrix and the color filter, a common electrode (not shown) disposed on the planarizing film, columnar photospacers (not shown) provided on the common electrode, and an alignment film (not shown) disposed on the common electrode.
The liquid crystal layer 25 is made of a nematic liquid crystal material that has electrooptical characteristics, for example.
The configuration of the liquid crystal display panel 1 of the present embodiment has a liquid crystal display element constituted of pixel electrodes, the liquid crystal layer 25 formed on the pixel electrodes, and a common electrode formed on the liquid crystal layer 25.
As shown in
The width of the sealing member 26 in the wide frame region F1 can be set to 0.4 mm to 1.6 mm, and the width of the narrow frame regions F2 can be set to 0.2 mm to 0.8 mm.
For the sealing material constituting this sealing member 26, it possible to appropriately use an ultraviolet curable resin such as an acrylic resin, urethane resin, polyester resin, and epoxy resin, or a light-curable resin such as a visible light curable resin that hardens when illuminated by visible light, such as an acrylic resin, methacrylic resin, epoxy resin, and silicone resin, for example. These resins may be used individually or two or more types of these resins may be used together simultaneously.
The liquid crystal display panel 1 has one pixel for each pixel electrode, and a prescribed amount of voltage is applied to the liquid crystal layer 25 at the respective pixels. The liquid crystal display panel 1 is configured such that the transmittance of light from the backlight is adjusted by changing the orientation state of the liquid crystal molecules by varying the amount of voltage applied to the liquid crystal layer 25, thereby causing an image to be displayed, for example.
Next, one example of a method of manufacturing the liquid crystal display panel of the present embodiment will be explained.
<Fabricating Mother Substrates>
A TFT mother substrate 60 shown in
A CF mother substrate 70 shown in
The black matrix is formed of a metal material such as Ta (tantalum), Cr (chromium), Mo (molybdenum), Ni (nickel), Ti (titanium), Cu (copper), or Al (aluminum), a resin material that has black pigment such as carbon dispersed therein, or a resin material or the like having a plurality of transmissive colored portions stacked together. In the present embodiment, as shown in
<Forming Sealing Member>
Next, a dispenser is used to draw the sealing member 26 in a frame shape having a width of 1 mm, for example, on the four sides of the frame region on the respective TFT substrates 10. As shown in
In this step, the dispenser coats unhardened sealing material onto the TFT substrate 10, during which the movement speed of the dispenser can be adjusted to control the discharge rate of the sealing material (in other words, to control the width of the sealing member 26).
Namely, increasing the movement speed of the dispenser (i.e., increasing the drawing speed) makes it possible to lower the discharge rate of the sealing material, and decreasing the movement speed of the dispenser (i.e., decreasing the movement speed) makes it possible to raise the discharge rate of the sealing material.
<Injecting Liquid Crystal>
Next, in a vacuum, liquid crystal is dripped inside the respective display areas D (namely, inside the respective sealing members 26) of the TFT substrates 10 on the mother substrate 60. The dripping of the liquid crystal material is performed by a dripping device having a liquid crystal dripping function dripping liquid crystal material over the entire substrate while moving, for example.
<Bonding to Form Bonded Member>
First, the TFT substrate 10 having the liquid crystal dripped therein in the step of injecting liquid crystal and the CF substrate 20 are bonded together in a depressurized environment such that the display areas D of each respectively overlap. Thereafter, the bonded member is exposed to the atmosphere to diffuse the liquid crystal material and form the liquid crystal layer 25, and a heating and pressurizing treatment is performed under prescribed parameters (pressure at 2.5 MPa and temperature at 150° C. for 30 minutes, for example) to adhere the sealing member 26 to the CF substrate 20 and, as shown in
At this time, as shown in
Next, the frame regions of the bonded member are illuminated with UV light to temporarily harden the sealing members 26 and then heated to permanently harden the sealing members 26, thereby bonding the mother substrate 60 to the mother substrate 70 and forming the bonded member 30 having the liquid crystal layer 25 sealed therebetween, as shown in
<Cutting>
Next, the edge of a super steel wheel contacts the front surface and rear surface of the bonded member 30 and cuts the bonded member 30 around each of the display areas D along the cutting line L described above, thereby manufacturing the liquid crystal display panel 1 shown in
At this time, the portions of the sealing member 26 located on the substrate bodies 11 and 12 from the cutting line L and outwards on the narrow frame regions F2 (or namely, opposite to the display area D side) are simultaneously cut along the cutting line L, but the wide frame region F1 on the terminal region T side is not cut. This makes the sealing member 26 have a narrower width than the portions thereof in the wide frame region F1, thereby manufacturing the liquid crystal display panel 1, which has end faces 1a (namely, end faces 10a of the TFT substrate 10 and end faces 20a of the CF substrate 20) on the narrow frame regions F2 shown in
More specifically, the manufactured liquid crystal display panel 1 has the end faces 26a of the sealing member 26 arranged in the narrow frame regions F2 so as to be along the respective end faces 1a of the liquid crystal display panel 1 in a plan view.
Accordingly, as shown in
The sealing member 26 is not cut in the wide frame region F1 on the terminal region T side, thereby making it possible to form the sealing member 26 at a significantly large width.
With this type of configuration, in the present embodiment, even if the wide sealing member 26 is formed on the cutting line L of the liquid crystal display panel 1 in the step of forming the sealing member, cutting the sealing member 26 along this cutting line L makes it possible for the sealing member 26 to have a sufficient width to ensure adhesive strength on the narrow frame regions F2. Therefore, the sealing member 26 is formed at the optimum width on the wide frame region F1 on the terminal region T side in the step of forming the sealing member, after which the sealing member 26 is not cut and can be made thicker. Accordingly, unlike in the conventional technology described above, the liquid crystal display panel 1 can prevent a decrease in adhesive strength of the sealing member 26 without increasing the number of manufacturing steps.
The width of the sealing member 26 in the narrow frame regions F2 can be set to 0.6 mm, for example.
The super steel wheel used for cutting is a disc-shaped cutting blade made of a cemented carbide such as tungsten carbide, for example, and the side face of the disc protrudes in a tapered fashion towards the center of the thickness direction thereof. The super steel wheel can have a protrusion formed at the tapered tip thereof.
Next, Embodiment 2 of the present invention will be described.
As shown in
As shown in
An insulating substrate 53 such as a glass substrate in a CF substrate 20 has provided thereon (on the sealing member 26 side of the CF substrate 20): a black matrix 54; a color filter 56 having colored portions 55 such as red portions R, green portions G, and blue portions B disposed so as to respectively correspond to the grid pattern of the black matrix 54; a planarizing film 57 covering the black matrix 54 and the color filter 56; and columnar photospacers 58 provided on the planarizing film 57.
As shown in
As described above, the planarizing films 52 and 57 are respectively provided on the TFT substrate 10 and the CF substrate 20, and are generally formed by spin coating or slit coating.
As shown in
Accordingly, in the display area D, the base is thick and the planarizing film is thin, and thus there is less material (for forming the planarizing film 57) flowing outward due to centrifugal force when forming the planarizing film 57 by spin coating, for example. This contrasts with the frame region (the wide frame region F1 and the narrow frame regions F2) where the base is thin and the planarizing film 57 is thick, which means that more material flows outward due to centrifugal force.
Thus, as shown in
As a result, there are problems in which the frame region (wide frame region F1 and narrow frame regions F2) has variation in the height of the sealing member 26; it is difficult to regulate the cell gap with the spacers 35; and variation occurs in the cell gap.
As a countermeasure, in the present embodiment, as shown in
Accordingly, the spacers 35 can prevent the deviations in height of the sealing member 26 in the wide frame region F1 and the narrow frame regions F2, and can prevent the occurrence of variation in the cell gap in the entire liquid crystal display panel 50 due to the cell gap in the wide frame region F1 being equal to the cell gap in the narrow frame regions F2.
The embodiments above may be modified in the following manner.
In the respective embodiments above, an example was described in which the liquid crystal display panel 1 was the display panel, but the present invention can also be applied to other display panels, such as an organic EL display panel, for example.
As shown in
This sealing member 43 is formed in a frame shape that surrounds the organic EL display element 42, and the circuit substrate 40 and the sealing substrate 41 are bonded to each other through this sealing member 43.
As shown in
A four-sided frame region where the sealing member 43 is provided is defined around the display area H, and as shown in
In a manner similar to the liquid crystal display panel 1 described above, the organic EL display panel 61 shown in
When manufacturing the organic EL display panel 61, in a manner similar to the liquid crystal display panel 1 described above, the sealing member 43 is formed in a frame shape along the four sides of the circuit substrate 40 in the step of forming the sealing member, and the sealing member 43 is formed on the narrow frame regions G2 of the circuit substrate 40 by straddling the cutting line of the circuit substrate in the step of cutting.
Next, in the step of bonding to form the bonded member, the circuit substrate 40 having the organic EL display element 42 formed thereon is bonded to the sealing substrate 41 in a depressurized environment such that the display regions H of each overlap, and the sealing member 43 is disposed in the narrow frame regions G2 of the sealing substrate 41 so as to straddle the cutting line of the sealing substrate 41 in the step of cutting.
In the step of cutting, the sealing member 43 formed straddling the cutting line on the substrate bodies outside the narrow frame regions G2 (or namely, opposite to the display area H side) are simultaneously cut along with the bonded member on the three narrow frame regions G2, but not the wide frame region G1 on the terminal region K side, thereby manufacturing the organic EL display panel 61 shown in
Accordingly, as shown in
In a manner similar to the liquid crystal display panel 50 described above, spacers (made of SiO2 (silicon oxide), for example) for regulating the gap between the circuit substrate 40 and the sealing substrate 41 may be provided in the sealing member 43, and a planarizing film may be provided on the sealing member 43 side of the circuit substrate 40 and the sealing substrate 41. Furthermore, as shown in
In the respective embodiments above, the portions of the sealing member 26 formed on the substrate bodies 11 and 12 outside the narrow frame regions F2 and straddling the cutting line L are cut on the corresponding three sides of the narrow frame regions F2, thereby manufacturing the liquid crystal display panel 1 in which the end faces 1a thereof are on the same plane as the end faces 26a of the sealing member 26, but a configuration may be used in which the portions of the sealing member 26 formed on the substrate bodies 11 and 12 outside the narrow frame regions F2 straddling the cutting line L are cut on one side or two sides of the narrow frame regions out of the three sides of the narrow frame regions F2.
In other words, in the present invention, the portion of the sealing member 26 formed on the substrate bodies 11 and 12 outside the narrow frame regions F2 straddling the cutting line L can be cut on at least one of the narrow frame regions F2 defined around the display area D to manufacture the liquid crystal display panel 1 having the end faces 1a thereof that are on the same plane as the end faces 26a of the sealing member 26.
In the respective embodiments above, an example was described in which the sealing member 26 is formed on the four sides of the frame region of the TFT substrate 10, but the sealing member 26 may be formed on the frame region of the CF substrate 20.
The respective widths of the narrow frame regions of the three sides described above may be the same size or may be different sizes.
As described above, the present invention is applicable to a display panel such as a liquid crystal display panel in which a pair of substrates overlap each other with a prescribed gap therebetween and then are bonded to each other via a sealing member, and a method of manufacturing this display panel.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-127268 | Jun 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/002748 | 4/23/2013 | WO | 00 |
