JPS60243639A - Liquid crystal color display device - Google Patents

Abstract

PURPOSE:To improve the efficiency of an operation for aligning upper and lower substrates and to mechanize said operation by forming alignment marks to the lower substrate in the stage of forming a pattern for picture element electrodes and to the upper substrate in the stage of forming a pattern for color filters. CONSTITUTION:An image screen part 17 and terminal parts 18 connecting leads, gates and a driver circuit to be attached external are formed to the lower substrate and the alignment marks 19 are disposed at four points on the outside of the part 17 where said marks do not overlap the sealant. The alignment marks 21 are disposed to the upper substrate in the stage of forming a color filter layer 20 in the image screen part. The efficiency of the operation for aligning the upper and lower substrates is thus improved and the mechanization of said operation is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a liquid crystal color display device. Furthermore, the present invention relates to improving the display quality of a liquid crystal color display device, and particularly to streamlining its manufacturing.

Liquid crystal displays can be driven at low voltages and with low power, and their applications have rapidly expanded in recent years as small, thin flat panel displays, and they have also been put to practical use as image display devices that can replace CRTs. I'm busy. There are two driving methods for liquid crystal displays: a time-division driving method and an active matrix driving method, and compact LCD TVs using both of these methods have already been released or prototypes have been announced. A prototype full-color LCD TV with vivid colors has also been announced by combining an LCD panel and a color filter. In the future, liquid crystal displays will become smaller and thinner flat displays.
A wide range of applications are possible.

[Prior art]

Figure 1 shows three color filters and thin film transistors (
1 is a cross-sectional view of a liquid crystal color display device in which an active matrix drive type liquid crystal shutter using TPT is combined. The display device includes a TP on which a pixel electrode 2 is formed.
A T-substrate 1 and a color filter substrate 6 on which a three-color color filter layer 4 of red (R), green (G), and blue (B) and a transparent electrode (1) are formed are bonded together via a sealing material 5. It has a structure in which nematic liquid crystal 10 is sealed between spaces. Further, polarizing plates 6 and 7 are pasted 9 on the top and bottom of the display device so as to form crossed Nicols.

Since this display device uses a color filter and is normally used as a transmission type, a backlight 9 is installed on the back side. Further, a partition plate 8 is usually used to hide the peripheral portion of the display device. This display device controls the light from the backlight 9 using a so-called twisted nematic mode in which the illumination properties of the liquid crystal layer are controlled by the voltage applied to each pixel electrode 2.

There are major problems in manufacturing such liquid crystal color display devices. That is, it is a problem of alignment between the pixel electrode 2 for driving the liquid crystal on the lower substrate and the color filter layer 4 on the upper substrate. FIG. 2 is an example of a pixel pattern on the lower substrate of the color display device.

There are a gate line 12 running in the horizontal direction, a lease line 16 running in the vertical direction, a pixel electrode 2, a double gate 14, a lease 15, and a drain 16 of a polycrystalline silicon transistor.

The dotted line in the figure is the pattern of the color filter layer formed on the upper substrate, and if aligned in this position, 100 pixel electrodes on the lower substrate will be included in the color filter of one color (for example, blue). Because of this, pure blue color can be displayed. However, if the alignment of the color filter is shifted to the upper left as shown in Figure 3, the red color filter layer will invade the originally blue pixel electrode, and this pixel will display a mixed color of blue and red. It becomes like this. Similarly, if it is shifted to the lower right, a mixture of blue and green will be displayed. Further, when the display shifts toward the upper right or lower left, red and green are mixed at the same time in the evening, and the display becomes white. The allowable amount of such deviation is approximately 10 μm step for a 19-inch screen panel with 240 pixels horizontally x 220 vertically and a pixel pitch of 160 μm horizontally x 130 μm vertically, and if there is a deviation of approximately 20 μm. However, I can feel that the color saturation has decreased. To prevent this, before curing the thermosetting spacer material 5, use a microscope to match the pixel electrode and filter layer patterns formed on the upper and lower substrates, and then apply UV-curable adhesive to the number of panels. After applying UV irradiation to the area,
A method was adopted in which the sealing material was cured. However, when aligning the upper and lower substrates by looking at the pixel electrode and filter layer patterns, there was a drawback that the process was time-consuming due to manual alignment.

〔the purpose〕

An object of the present invention is to improve the efficiency and mechanize the alignment work of the above-mentioned upper and lower substrates. Furthermore, the present invention does not require any additional steps other than the formation of the original pixel electrodes and color filter layer.

〔overview〕

In order to satisfy the above object, the gist of the present invention is to create marks for vertical alignment. Furthermore, in order to avoid creating an additional process for creating alignment marks, the lower substrate is used when forming the pixel electrode pattern, and the upper substrate is used when forming the color filter layer pattern.
This involves creating alignment marks. It is also conceivable to create alignment marks when creating additional patterns for other reasons.

〔Example〕

a) Example 1 Example 1 is an example in which a turn of polycrystalline silicon forming a gate line is used as an alignment mark on the lower substrate side, and a pattern of a color filter layer is used as an alignment mark on the upper substrate side.

FIGS. 4 and 5 are diagrams showing the arrangement of alignment marks on the lower and upper substrates of Example 1, respectively.

On the lower board in FIG. 4, there is a terminal section 18 that connects the screen section 17, the lease and gate lines, and an external driver circuit, but the alignment mark 19 is located outside the screen section and does not overlap with the sealing material. It is placed in several places. On the upper substrate in FIG. 5, alignment marks 21 are arranged near four corners of the color filter layer 20 in the screen portion.

FIG. 6 is an enlarged view of the alignment marks of the upper and lower substrates of Example 1 viewed overlappingly. The outer opening, the cross-shaped mark, is the mark 19 on the lower substrate, which is the same polycrystalline silicon thin film as the gate line, and is a brown translucent thin film.

The inner rectangular mark 21 is a mark on the upper substrate and is made in the same process as the color filter layer. Color filters have three primary colors, but blue, which has low light transmittance, is the easiest to recognize as an alignment mark. Furthermore, although the alignment marks at the four locations may be of different colors, it is better to unify them to the same color, which has the advantage that even if there is a slight deviation in alignment between the patterns of each of the three primary colors, there will be no effect.

b) Example 2 In Example 2, the material of the alignment mark on the upper substrate side of Example 1 was changed. Therefore, there are no major changes to the marks on each board. The color filter layer can be fabricated on the upper substrate using dyeing methods, printing methods, photographic plate methods, electrodeposition methods, vacuum evaporation methods, etc.; law is considered the best. A typical manufacturing method for dyeing is as follows. A transparent substrate is coated with a dye layer of gelatin, gris, casein, etc., exposed to light, suspended and developed to create a pattern, which is then dyed with a dye of the desired color. Furthermore, a retentive film is coated on top of this. The above is the process for one color of the three primary colors RGB, and this is repeated three times. At this time, an alignment mark is required for alignment with the previously created Cassie filter pattern. There is a method of using the filter layer made in the previous process as the alignment mark, but if the combination of the color of the color filter layer and the wavelength of the light source of the alignment machine is not good, the alignment mark becomes very difficult to see, and it is not possible to use an automated alignment machine. It becomes difficult. For this purpose, there is a method of forming a thin metal film (chromium, nickel, etc.) for the alignment mark by vapor deposition, sputtering, plating, etc. before forming the filter layer. In Example 2, alignment marks for the upper and lower substrates are formed using this metal thin film. In this case, the process of aligning the upper and lower substrates can also be automated because pattern recognition by a machine is easier than with a color filter layer. FIG. 7 is one of the second embodiments for automated alignment. The ring 22 on the outer periphery is an alignment mark for the dry silicon of a certain lower layer, and the inner circle 23 is an alignment mark for the metal thin film on the upper substrate. Concentric marks are provided to facilitate automatic alignment.

As can be said in common with Examples 1 and 2, it goes without saying that the shape of the alignment mark may be upside down. Further, the shape of the alignment mark is just one example, and any shape may be used as long as alignment is possible.

〔effect〕

As described above, by using the present invention, the alignment work of the upper and lower substrates can be simplified and made more efficient without increasing the number of steps for forming patterns on the upper and lower substrates.

Further, it is possible to automate the alignment work, thereby reducing the cost of the liquid crystal color display device and improving the display quality (percentage of color), and the effects of the present invention are very large.

In this application, an example of an active matrix drive type liquid crystal color display device is given, but it goes without saying that the present invention can be applied to a display device in which pixel electrodes and color filters are separated into upper and lower substrates.

[Brief explanation of the drawing]

FIG. 1: A sectional view of a liquid crystal color display device. 1-
TFT substrate, 21 pixel electrode, 6-color filter substrate, 4-color filter layer, 5-sealing material, 6.7-polarizing plate, 8-parting plate, ? -Backlight, 101 LCD,
11-Transparent electrode. FIG. 2: Pixel pattern diagram of a liquid crystal color display device. 12-gate line, 16-lease line, 14-
Double gate, 15-lease, 16-drain. Figure 6: Example of misalignment of color filters. FIG. 4: A layout diagram of alignment marks on the TPT substrate of Example 1. 17 - screen section, 18 - terminal section, 1
9- Alignment mark. FIG. 5: A layout diagram of alignment marks on the color filter substrate of Example 1. 20-Color filter layer, 21-Alignment mark FIG. 6...An enlarged view when the alignment marks of Example 1 are overlapped. FIG. 7: An enlarged view when alignment marks of Example 2 are overlapped. Applicant: Suwa Seikosha Co., Ltd. Figure 1 Figure 2 W Figure 4 Figure 5 Figure 7

Claims (1)

[Claims] 1) In a liquid crystal color display device composed of pixels of a liquid crystal shutter arranged in a matrix and three primary color filters of red, green, and blue arranged correspondingly, two upper and lower A liquid crystal color display device characterized in that alignment marks are formed in each unique process. 2) The liquid crystal color display device according to claim 1, wherein the liquid crystal color display device has a pattern formed in the same process as forming a filter layer of a color filter as a vertical alignment mark. 6) The liquid crystal color display device according to claim 1, wherein the liquid crystal color display device has a pattern formed in the same process as forming the liquid crystal driving pixel pattern as the vertical alignment mark. 4) The liquid crystal color display device according to claim 2, wherein the liquid crystal color display device has a pattern formed in the same process as forming a filter layer of a specific color of a color filter as a vertical alignment mark. 5) The liquid crystal color display device according to claim 1, further comprising a metal pattern formed in advance for forming a filter layer of a color filter by a photoetching method as a vertical alignment mark.