Patent Application
20070181921
This application claims the benefit of Korean Patent Application No. 2006-0004547, filed on Jan. 16, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
The present invention relates to a display device having black matrixes formed on a plastic insulating substrate better aligned with color filters.
An LCD flat panel display includes an LCD panel having a thin film transistor (TFT) substrate, a color filter substrate opposite the TFT substrate and a liquid crystal layer located between the two substrates. A backlight unit is located in back of the TFT substrate to provide light to the LCD panel. For lightness and thinness a plastic insulating substrate may be used. Under certain circumstances, however, misalignment of the color filters with the black matrixes may occur.
In accordance with an aspect of the present invention improved alignment of black matrixes with color filters is provided in a display device having a first insulating substrate comprising a first insulating substrate and thin film transistors formed on the first insulating substrate; a second substrate facing the first substrate and comprising a second insulating substrate made of plastic and a black matrix formed on the second insulating substrate, the black matrix comprising a plurality of horizontal extending portions extending in a first direction and disposed at fixed or irregular intervals and a plurality of vertical extending portions extending in a second, perpendicular direction and disposed at an irregular interval; and a liquid crystal layer located between the first and second substrates. According to an embodiment of the present invention, the vertical extending portions comprise: a first sub vertical portion having a first vertical width and a second sub vertical portion having a second vertical width larger than the first vertical width.
According to an embodiment of the present invention, the second substrate further comprises color filters formed on the black matrixes with a constant interval.
According to the embodiment of the present invention, an interval between the adjacent horizontal extending portions includes first horizontal intervals and second horizontal intervals smaller than the first horizontal intervals, and wherein the horizontal extending portions comprise: a first sub horizontal portion having a first horizontal width; and a second sub horizontal portion having a second horizontal width larger than the first horizontal width.
According to the embodiment of the present invention, the display device further comprises color filters formed on the black matrixes and the second insulating substrate, the color filters having a plurality of sub layers extending in the second direction and having an irregular interval.
The display device of the invention may be manufactured by: forming a black matrix on an insulating plastic substrate, the black matrix comprising a plurality of horizontal extending portions extending in a first direction and a plurality of vertical extending portions having an irregular interval and extending in a second direction perpendicular to the first direction; and forming color filters in openings formed in the black matrix with a constant interval.
The above and/or other aspects and advantages of the present invention will become apparent from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
A display device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. A display device 1 includes a first substrate 100 on which TFTs T are formed, a second substrate 200 opposite to the first substrate 100 and on which a common electrode 251 is formed, a sealant 300 adhering both substrates 100 and 200 together, and a liquid crystal layer 400 bounded by substrates 100, 200 and sealant 300. First and second substrates 100 and 200 are rectangular in shape, with the first substrate 100 somewhat larger than the second substrate 200. The first and second substrates 100 and 200 are each divided into a display region in which the TFTs T are located and a non-display region surrounding the display region and at which the sealant 300 and pads 123 and 144 are formed.
The first substrate 100 will be now described in detail. Gate conductor lines 121, 122 and 123 are formed on a first insulating substrate 110, which may be made of plastics or glass.
Gate conductor lines 121, 122 and 123 include gate lines 121 extending in parallel transversely, gate electrodes 122 of the TFTs T which are connected to the gate lines 121, and gate pads 123 provided at the ends of the gate lines 121. Gate pads 123 are wider than gate lines 121 in order to facilitate their connection to an external circuit.
A gate insulating film 131 made of silicon nitride (SiNx) is formed on the first insulating substrate 110 and on gate conductor lines 121, 122 and 123.
A semiconductor layer 132 made of a semiconductor material such as amorphous silicon or the like is formed on gate insulating film 131 of gate electrode 122, and an ohmic contact layer 133 made of a material such as silicide, n+ hydrogenated amorphous silicon heavily doped with n-type impurities, or the like is formed on semiconductor layer 132. Semiconductor layer 132 has an island-like shape on gate electrode 122 and ohmic contact layer 133 is divided into two portions around gate electrode 122.
Data conductor lines 141, 142, 143 and 144 are formed on ohmic contact layer 133 and gate insulating film 131. Data conductor lines 141, 142, 143 and 144 include a data line 141 formed perpendicular to gate line 121, with pixels defined by the intersection of data line 141 and gate line 121. A source electrode 142, which is a branch of data line 141, extends to the top of ohmic contact layer 133, a drain electrode 143 is formed opposite to and separated from source electrode 142 around gate electrode 122, and data pads 144 are formed at the end of data line 141. Data pads 144 are wider than data line 141 i to facilitate their connection to an external circuit.
A passivation film 151 made of a material such as silicon nitride, a-Si:C:O or a-Si:O:F deposited by a plasma enhanced chemical vapor deposition (PECVD) method is formed on the data conductor lines 141, 142, 143 and 144 and a portion of the semiconductor layer 132, which is not covered with the data conductor lines 141, 142, 143 and 144. In the passivation film 151 are formed a contact hole 171 exposing the drain electrode 143, a contact hole 172 exposing the gate pad 123, and a contact hole 173 exposing the data pad 144.
Transparent conductive layers 161, 162 and 163 made of a transparent conductive material such as indium tine oxide (ITO) or indium zinc oxide (IZO) are formed on the passivation film 151. The transparent conductive layers 161, 162 and 163 includes a pixel electrode 161 connected to the TFT T via contact hole 171 exposing drain electrode 143, a first contact member 162 formed on the contact hole 172 exposing gate pad 123, and a second contact member 163 formed on contact hole 173 exposing data pad 144.
Next, the second substrate 200 opposite to the first substrate 100 will be described in detail. Black matrixes 220 are formed on a second insulating substrate 120, which may be made of plastic such as polycarbonate, polyimide, polyethersulfone (PES), polyarylate (PAR), polyethylenenaphtalate (PEN), polyethyleneterephthalate (PET) or the like.
Black matrixes 220, in the form of a lattice, include inner black matrixes 220a formed in the display region and outer black matrixes 220b formed in the non-display region. The inner black matrixes 220a are formed to correspond to gate line 121, data line 141 and TFT T. The inner black matrixes 220a block external light from the channel region of the TFT T, and outer black matrixes 220b are formed to surround the display region. Outer black matrixes 220b are wider than inner black matrixes 220a. Black matrixes 220 (including the inner and outer black matrixes 220a and 220b) may be made of chrome oxide, or organic materials containing black pigments.
Color filters 230 are formed between the black matrixes 220. The color filters 230 are regularly formed. That is, three sub layers 230a, 230b and 230c having different colors are repeatedly formed.
An overcoat layer 241 is formed on color filters 230 to planarize the surface.
A common electrode 251 is formed on overcoat layer 241. Common electrode 251, which is made of a transparent conductive material such as ITO, IZO or the like, controls alignment of molecules in the liquid crystal layer 400 by applying a voltage to the liquid crystal layer 400 in combination with the pixel electrode 161.
Although not shown, alignment films are formed on pixel electrode 161 and common electrode 251, respectively. The alignment films are typically made of polyimide and are rubbed to orient the molecules in the liquid crystal layer 400 in a specific direction.
Sealant 300 is applied in the non-display region along the circumference of the display region and contains ultraviolet curing resin such as acryl resin or may further contain a thermosetting resin such as epoxy resin, amine curing agent, a filler such as alumina powder, and a spacer.
The liquid crystal layer 400 is located in the space between substrates 100 and 200, and alignment of the molecules therein is changed by a voltage difference between the pixel electrode 161 and the common electrode 251.
Hereinafter, the black matrixes 220 of the display device according to the first embodiment of the present invention will be described in more detail with reference to
Inner black matrix 220a includes a horizontal extending portion 221 and a vertical extending portion 222. The horizontal extending portion 221 and the vertical extending portion 222 are perpendicular to each other, defining an opening C.
A narrow line segment A of the inner black matrix 220a overlaps gate line 121 and data line 141, and a wide line segment B at an intersection portion of the horizontal extending portion 221 and the vertical extending portion 222 overlaps the TFT.
The second substrate 200 including the inner black matrix 220a has a largely rectangular shape. The horizontal extending portion 221 extends in a first direction in parallel to the long sides of the second substrate 200, while the vertical extending portion 222 extends in a second direction in parallel to the shorts sides of the second substrate 200.
Intervals between inner black matrixes 220a will be now considered below.
The spacing between vertical extending portions 222 is irregular and includes a first interval d1 and a second interval d2 narrower than the first interval d2. The first interval d1 and the second interval d2 have a regular pattern of one second interval d2 every six first intervals d1.
The second interval d2 may be 70% to 98% of the first interval d1. If the second interval d2 is less than 70% of the first interval d1, an area of the opening C is excessively reduced. If the second interval d2 is more than 98% of the first interval d1, an alignment between the color filters 230 and black matrixes 220 deteriorates. A size of the second interval d2 depends on a thermal expansion coefficient of the second insulating substrate 210, temperature conditions for manufacture of the color filters 230, a ratio of the first interval d1 to the second interval d2, etc. The interval between horizontal extending portions 221 is a regular third interval d3.
Color filters 230 extend along the second direction in parallel to the short sides of the second substrate 200, with the sub layers 230a, 230b and 230c repeatedly formed. The color filters 230 are arranged at regular intervals, with an interval between the sub layers 230a, 230b and 230c as a fourth interval d4. The width of each color filter 230 is constant at a first width w1.
As shown in
This is because the black matrixes 220 are formed on the second insulating substrate 210 made of plastic. Since plastics have a thermal expansion coefficient higher than glass, a plastic insulating substrate is apt to expand when heated, unlike a glass insulating substrate.
Plastic insulating substrate 210 expands by the heat generated during various processes, such as coating, exposure, development, baking and so on, which are repeatedly performed in manufacturing color filters 230. The expansion of the plastic insulating substrate 210 causes expansion of the black matrixes 220 formed on the plastic insulating substrate 110, which may result in misalignment of the black matrixes 220 with the color filters 230. Excessive expansion of the black matrixes 220 may cause the color filters 230 not to be located at the openings C of the black matrixes 220, which may result in leakage of light.
For example, if the diagonal of plastic insulating substrate is 7 inches, the amount of expansion of the plastic insulating substrate may be in an order of about 50 μm. Expansion in a long side direction of the second substrate 200 is larger than that in a short side direction of the second substrate 200, and thus increasing an interval between the vertical extending portions 222.
In this embodiment, the interval between the vertical extending portions 222 includes the relatively small second interval d2, as mentioned above. Expansion of the interval between the vertical extending portions 222, that is, expansion of the black matrixes 220 in the first direction, is restricted by the second interval d2, thus decreasing the misalignment of the black matrixes 220 with the color filters 230. Since the second interval d2 is formed with a constant pattern throughout the second substrate 200, the misalignment of the black matrixes 220 with the color filters 230 decreases throughout the second substrate 200.
As shown in
While the color filters 230 are formed, the black matrixes 220 are expanded into the state shown in
After forming the black matrixes 220, the second substrate 200 is completed when the color filter layer 230, the overcoat layer 241 and the common electrode 251 are formed on the black matrixes 220.
The first substrate 100 may be manufactured according to a known method, and therefore, explanation thereof will be omitted for the sake of brevity. Bonding of the first substrate 100 to the second substrate 200 and injection of the liquid crystal layer 400 may also be performed according to a known method, and therefore, explanation thereof will be omitted for the sake of brevity.
The above-described first embodiment may be modified in various ways. For example, the interval between the vertical extending portions 222 may have an irregular pattern and may include 3 or more different intervals.
Vertical extending portions 222 include an enlarged vertical extending portions 222a having a width larger than the second width w2 of adjacent vertical extending portions 222. The interval between the enlarged vertical extending portions 222a and the adjacent vertical extending portions 222 is the second interval d2.
A fourth width w4 as a width of the enlarged vertical extending portions 222a may be 102% to 130% of the second width w2. The size of the fourth width w4 depends on the thermal expansion coefficient of the second insulating substrate 210, temperature conditions for manufacture of the color filters 230, etc.
Hereinafter, a display device according to a third embodiment of the present invention will be described with reference to
The interval between vertical extending portions 222 includes a first interval d1 and a second interval d2 smaller than the first interval d2, as in the first embodiment. The first interval d1 and the second interval d2 have a regular pattern of one second interval d2 every six first intervals d1.
In the third embodiment, in addition, the interval between horizontal extending portions 221 includes a third interval d3 and a seventh interval d7 smaller than the third interval d2. The third interval d3 and the seventh interval d7 have a constant pattern of one seventh interval d7 every 10 third intervals d3. The reason for irregularity of the interval between the horizontal extending portions 221 is that the third embodiment is different in arrangement of the color filters 230 from the first embodiment.
Referring to
The seventh interval d7 may be 70% to 98% of the third interval d3. If the seventh interval d7 is less than 70% of the third interval d3, an area of the opening C is excessively reduced. If the seventh interval d7 is more than 98% of the third interval d3, an alignment between color filters 230 and black matrixes 220 deteriorates. A size of the seventh interval d7 depends on a thermal expansion coefficient of the second insulating substrate 210, temperature conditions for manufacture of the color filters 230, a ratio of the third interval d3 to the seventh interval d7, etc.
As an alternative, the interval between the horizontal extending portions 221 may have an irregular pattern and may include three or more different intervals.
Hereinafter, a display device according to a fourth embodiment of the present invention will be described with reference to
As shown in
As an alternative, it may be configured that the interval between the black matrixes 220 and the interval between the color filters 230 are made irregular simultaneously. For example, the black matrixes 220 may have a narrow interval every a specified position, while the color filters 230 may have a wide interval every a specified position.
As apparent from the above description, the present invention provides a display device having reduced misalignment of black matrixes with color filters even when a plastic insulating substrate is used.
In addition, the present invention provides a manufacturing method of a display device having improved alignment of black matrixes with color filters even when a plastic insulating substrate is used.
Although a few embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without, however, departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-0004547 | Jan 2006 | KR | national |
