JP2003255391A - Method for manufacturing liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a conductive tape from being peeled from a terminal part, to prevent an adhesive overflowing when two liquid crystal panels are superposed on each other from being stuck to a lead electrode and to obtain satisfactory visibility of an alignment mark, when the two liquid crystal panels having a chiral nematic liquid crystal are laminated. <P>SOLUTION: A conductive tape having the width narrower than the longitudinal width Wy of the terminal part and the length longer than the lateral width Wx of the terminal part is stuck to each terminal part 11a, 12a, 21a and 22a of the liquid crystal panels 10 and 20 via a conductive paste and a cover film is stuck onto each conductive tape so as to cover the entire surface of each terminal part and then the adhesive is applied to superposing surfaces of the liquid crystal panels to superpose the panels on each other. Alignment of the panels is performed in a state in which the visibility of the alignment marks formed at each liquid crystal panel are made satisfactory by supplying current to each liquid crystal panel via each conductive tape to homeotropically align the chiral nematic liquid crystal. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a technique for assembling a laminated liquid crystal display device in which two liquid crystal panels each having a chiral nematic liquid crystal are laminated. Is.

[0002]

2. Description of the Related Art A chiral nematic liquid crystal is known as a liquid crystal having a memory property, has a planar alignment in the absence of an electric field, and selectively reflects colored light according to the helical pitch of the liquid crystal. When a predetermined electric field is applied, the orientation changes to the focal conic orientation, and light is transmitted, and this state is maintained even when the electric field is released. When a higher electric field is applied from the focal conic state, homeotropic alignment is obtained and transparency is further increased, but when the electric field is released from this state, the alignment changes to planar alignment.

When multi-color display is performed by utilizing the selectively reflected light in the planar state, two or more liquid crystal panels are laminated, but in that case, alignment of each liquid crystal panel becomes an important problem. Therefore, conventionally, a conductive tape (for example, a copper tape) is attached to a predetermined lead electrode formed on the terminal portion of the liquid crystal panel via a conductive glue, and the terminal is taken out. By energizing, the alignment mark formed on each liquid crystal panel is turned on, the CCD camera captures an image of the alignment mark, and the alignment is performed while visually recognizing it on the monitor.

An adhesive is used to bond the two liquid crystal panels, but a slightly larger amount of the adhesive is applied in order to bond the entire surfaces of the bonded surfaces without leaving bubbles. Therefore, although it is a small amount at the time of bonding, the adhesive may stick out and adhere to the lead electrode, which may hinder the subsequent TAB connection.

In order to prevent this, conventionally, a wide conductive tape is attached to the entire surface of the terminal portion on which the lead electrodes are formed, and masking is performed so that the adhesive does not adhere to the lead electrodes.

However, since the conductive adhesive (adhesive containing carbon, for example) has a weak adhesive force, the conductive tape may be peeled off during the superposition work, and the fragments may enter the superposition surface. There is a defect.

Further, the chiral nematic liquid crystal is set in the planar or focal conic state so that the alignment mark can be visually recognized. However, when the two liquid crystal panels are stacked, the alignment mark is actually difficult to see and the accurate alignment is possible. Difficult to match. for that reason,
Work tends to be delayed.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent the conductive tape from being peeled off from the terminal portion during the work, and to prevent the adhesive protruding during the stacking from adhering to the lead electrode. In addition, the visibility of the alignment mark is improved so that the alignment work can be performed quickly.

[0009]

In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a liquid crystal display element comprising a first liquid crystal panel and a second liquid crystal panel, both of which have a chiral nematic liquid crystal. The width in the direction from the edge of the terminal part of the liquid crystal panel to the peripheral sealing material is defined as the vertical width of the terminal part, and the width in the direction orthogonal to the vertical width direction is defined as the lateral width of the terminal part. , A conductive tape whose width is narrower than the vertical width of the terminal portion and whose length is longer than the horizontal width of the terminal portion is spread over all the lead electrodes formed on the terminal portion with a conductive paste. First step of adhering a cover film from above on it with a predetermined adhesive so as to cover the entire surface of the terminal portion, and superimposing the first liquid crystal panel and the second liquid crystal panel on each other. Apply adhesive to the surface Second step of stacking liquid crystal panels, and third step of conducting alignment by energizing each of the liquid crystal panels through the conductive tape to make the alignment marks formed on each of the liquid crystal panels visible It is characterized by including and.

According to this structure, the conductive tape is pressed by the cover film, so that the conductive tape is not easily peeled off during the work. Further, since the lead electrode forming surface of the terminal portion is covered with the cover film, the adhesive does not adhere to the lead electrodes.

Another feature of the present invention is that the chiral nematic liquid crystal of each liquid crystal panel is brought into the homeotropic state when the alignment mark in the third step is visually recognized. According to this, the transparency of the liquid crystal becomes the best, and the alignment mark can be satisfactorily visually recognized even when two liquid crystal panels are stacked.

Further, after completion of the alignment in the third step, it is preferable to partially apply an ultraviolet curable resin for temporary fixing between the liquid crystal panels and irradiate ultraviolet rays to perform temporary fixing. This point is also one of the features of the present invention.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described. FIG. 1 shows two liquid crystal panels laminated according to the present invention. For convenience of explanation, the upper liquid crystal panel in FIG. 1 is referred to as an upper panel 10, and the lower liquid crystal panel is referred to as a lower panel 20.

In both the upper panel 10 and the lower panel 20, a pair of transparent electrode substrates (segment side substrate, common side substrate) are pressure-bonded via a peripheral sealing material (not shown). A chiral nematic liquid crystal is enclosed in the gap.

In this embodiment, the top panel 10
Includes a terminal portion 11a and a terminal portion 12a on the segment side substrate 11 and the common side substrate 12, respectively. Similarly, the lower panel 20 also includes a terminal portion 21a and a terminal portion 22a on the segment side substrate 21 and the common side substrate 22, respectively.

Alignment marks 13a, 13b are formed at diagonal positions on the display surface of the upper panel 10, and similarly, alignment marks 23a, 13b are formed at the same diagonal positions on the display surface of the lower panel 20. 23b is formed.

The alignment marks 13a and 23b form a pair, and the alignment marks 13b and 23a form a pair. As shown in the enlarged view of FIG. 2, one of the alignment marks 13a and 23a is used as a serpentine line. Then, the other alignment marks 13b and 23b are formed as medium black circular dots which are smaller than the inner diameter of the serpentine by a predetermined dimension.

Here, taking the terminal portion 22a as an example, the width in the direction from the edge to the peripheral sealing material is the vertical width Wy of the terminal portion.
Then, the stacking procedure of the upper panel 10 and the lower panel 20 will be described with the width in the direction orthogonal to the vertical width direction as the lateral width Wx of the terminal portion. It is assumed that the upper panel 10 and the lower panel 20 have both completed the leak inspection.

First, the terminal portions 11a, 12a, 21a,
A conductive tape is attached to each of 22a. This pasted state will be described by taking the terminal portion 22a shown in FIG. 3 as an example.
For the conductive tape 30, for example, a copper tape whose width is narrower than the vertical width Wy of the terminal portion 22a and whose length is longer than the horizontal width Wx is used.

For example, the vertical width Wy of the terminal portion 22a is 3.5.
mm, the width of the conductive tape 30 is 2.0 m
m is attached to the center of the terminal portion 22a. In that case, the conductive tape 30 is made to straddle all the lead electrodes 221 formed on the terminal portion 22a, and one end 30a thereof is pulled out from the end of the terminal portion 22a by, for example, about 2.0 mm. To attach the conductive tape 30, a conductive paste made of, for example, carbon mixed in an adhesive is used.

Next, as shown in FIG. 4, the conductive tape 3
A cover film 40 having a small thickness is attached on the surface of the surface of No. 0 via an adhesive having an adhesive strength higher than that of the conductive paste.
A polyimide film is suitable for the cover film 40 and is attached so as to cover the entire surface of the lead electrode formation surface of the terminal portion 22a.

In this case, it is preferable that the cover film 40 is attached to be slightly larger and then the portion protruding from the terminal portion 22a is cut. Similarly, the cover film 40 is attached on the conductive tape 30 for the other terminal portions.

Next, in this example, black paint, which is the background color of the display, is printed on the back surface of the lower panel 20. In this printing, static electricity may be charged and often cause partial lighting, but since the conductive tape 30 electrically connects the display electrodes of the panels 10 and 20 to each other, it is also useful for preventing partial lighting. In addition, if necessary, the conductive tape 30
By energizing each of the panels 10 and 20, a lighting (entire lighting) test as an intermediate test can be performed.

Returning to FIG. 1, next, for example, the upper panel 10
Stacking side (in this example, the back side of the common side substrate 12)
An adhesive (not shown) is applied to the entire surface of the substrate by a screen printing method or the like.

Then, the upper panel 10 and the lower panel 20
And overlap. In this case, it is preferable that the superposing operation is performed in a low vacuum tank in order to prevent bubbles from remaining on the superposing surfaces. At this time, even if the adhesive protrudes, the adhesive does not adhere to the lead electrodes because the lead electrode forming surface of the terminal portion is covered with the cover film.

After that, the upper panel 10 and the lower panel 2
The laminated panel formed by superimposing 0 and 0 is set on a positioning device (not shown) equipped with a CCD camera. The alignment device includes an upper table and a lower table, and one of the tables is movable in the XY and Z axis directions and rotatable in the θ direction about the Z axis. Is preferably used.

Next, a sliderac or oscillator (not shown) is connected to each conductive tape 30, and the upper panel 10 is connected.
While the lower panel 20 and the lower panel 20 are turned on at the same time to make the alignment marks 13a, 13b; 23a, 23b visible, the alignment marks are imaged by a CCD camera and displayed on a monitor.

When making the above-mentioned alignment marks visible, it is preferable that both the chiral nematic liquid crystals of the panels 10 and 20 are in the homeotropic state with the best transparency.

Then, as shown in FIG. 2, the movable table of the alignment device is moved and aligned so that the alignment marks 23b, 13b of the other alignment marks 13a, 23a are placed in the lanes of the other alignment mark. .

After the alignment is completed, each panel 10, 2
For example, an ultraviolet curable resin for temporary fixing is applied to a corner portion of 0 using a dispenser, and the ultraviolet curable resin is irradiated with ultraviolet rays to be temporarily fixed. After the temporary fixing, if the adhesive is a room temperature curing type, it is allowed to stand until it hardens, and if it is a thermosetting type, it is cured in a heating atmosphere.

Then, if necessary, each panel 10, 20 is energized from the conductive tape 30 to perform a final lighting inspection (mainly lighting unevenness inspection) and a visual inspection to remove the cover film 40 and the conductive tape 30. By removing and cleaning each terminal part, all work of lamination is completed.

In the above embodiment, the conductive tape 30 and the cover film 40 are attached to all four terminal portions, but there is no fear that the protruding adhesive will adhere to the lead electrodes, and moreover, for example, the alignment. When set in the device, the conductive tape 30 is used for the terminal parts (in the example of FIG. 1, the terminal parts 12a and 21a) capable of supplying power from the alignment device through an electrical connecting means such as conductive rubber. It is not necessary to attach the cover film 40.

Further, the present invention is not limited to the above-mentioned embodiment, and the display electrode of one transparent electrode substrate is connected to the terminal portion on the other transparent electrode substrate side, for example, via the transfer means in the peripheral sealing material. Then, it is naturally applicable to so-called unidirectional extraction liquid crystal panel stacking with one terminal portion.

[0034]

As described above, according to the present invention,
In stacking two liquid crystal panels having a chiral nematic liquid crystal, the width of each liquid crystal panel terminal portion is narrower than the vertical width Wy of the terminal portion and the length is horizontal width W of the terminal portion.
A conductive tape longer than x is adhered via a conductive adhesive so as to straddle all the lead electrodes formed on the terminal portion, and a predetermined adhesive is applied so as to cover the entire surface of the terminal portion from above. After applying a cover film, apply an adhesive to the stacking surface of the liquid crystal panel and stack them together, and energize each liquid crystal panel through the conductive tape to align the alignment marks on each liquid crystal panel. By making the position visible and performing the alignment, it is possible to prevent the conductive tape from being peeled from the terminal portion during the work, and to reliably prevent the adhesive protruding during the superposition from adhering to the lead electrode.

Further, the chiral nematic liquid crystals of each liquid crystal panel are simultaneously homeotropically aligned,
Even when two liquid crystal panels are stacked, the alignment mark can be visually recognized well, and thus the alignment work can be performed quickly.

[Brief description of drawings]

FIG. 1 is a perspective view schematically illustrating two liquid crystal panels laminated according to the present invention.

FIG. 2 is an enlarged view exemplifying an alignment mark formed on the liquid crystal panel.

FIG. 3 is an enlarged perspective view for explaining a state in which a conductive tape is attached to the terminal portion of the liquid crystal panel.

FIG. 4 is an enlarged perspective view for explaining a state in which a cover film is further attached onto the conductive tape attached to the terminal portion of the liquid crystal panel.

[Explanation of symbols]

10, 20 LCD panel 11,21 Segment side substrate 12,22 Common side board 11a, 12a, 21a, 22a Terminal part 13a, 13b, 23a, 23b Alignment mark 30 conductive tape 40 cover film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/35 G09F 9/35 F term (reference) 2H088 FA01 FA03 FA30 GA02 GA17 HA03 MA20 2H089 HA21 NA38 NA39 NA41 NA42 NA44 NA45 NA60 PA15 QA12 RA05 TA03 TA04 TA06 TA11 TA17 2H092 GA32 GA48 GA51 GA55 GA57 MA01 MA10 NA27 5C094 AA43 AA53 BA07 BA09 BA49 DA12 DB02 FB06 GB01 HA08 5G435 AA17 BB12 BB16 EE42 GG42 KK05 LL06 LL07 LL06 LL07 LL07

Claims (3)

[Claims] 1. A method of manufacturing a liquid crystal display element, which comprises a first liquid crystal panel and a second liquid crystal panel both having chiral nematic liquid crystal, wherein a direction from an edge of a terminal portion of the liquid crystal panel to a peripheral sealing material is provided. The width of the terminal portion is the vertical width, and the width in the direction orthogonal to the vertical width direction is the horizontal width of the terminal portion, and in each terminal portion of the liquid crystal panel, the width is narrower than the vertical width of the terminal portion, and A conductive tape having a length longer than the lateral width of the terminal portion is adhered via a conductive paste so as to extend over all the lead electrodes formed on the terminal portion, and then the entire surface of the terminal portion is applied from above. A first step of attaching a cover film via a predetermined adhesive so as to cover the liquid crystal panel, and applying an adhesive to the superposed surfaces of the first liquid crystal panel and the second liquid crystal panel to laminate the liquid crystal panels. The second step and the conductive tape And a third step of aligning the liquid crystal panels by energizing the liquid crystal panels so that the alignment marks formed on each of the liquid crystal panels can be visually confirmed. . 2. The method of manufacturing a liquid crystal display device according to claim 1, wherein the chiral nematic liquid crystal of each liquid crystal panel is brought into a homeotropic state when the alignment mark in the third step is visually recognized. 3. After completion of the alignment in the third step,
The ultraviolet curable resin for temporary fixing is partially applied between the liquid crystal panels, and ultraviolet rays are irradiated to temporarily fix the resin.
Alternatively, the method for manufacturing the liquid crystal display element according to the item 2.