JPH04365015A - Electrode connecting method for liquid crystal display panel - Google Patents

Abstract

PURPOSE:To facilitate the connection of an electrode, and prevent the open circuit defect of a flexible circuit board. CONSTITUTION:A long hole 31 is formed on the inside of one end edge of the reinforcing plate 30 of a liquid crystal panel to provide a belt-shaped portion 32. The segment side connector electrode terminal section 22a of a flexible circuit board 20 constituting the driving circuit of the liquid crystal panel is inserted into the long hole 31 from the back face side of the reinforcing plate 30. The segment side connector electrode terminal section 22a is lightly fixed to the belt-shaped portion 32 on the surface side of the reinforcing plate 30 so that a connecting terminal 23a is faced upward. A segment electrode terminal section formed on the lower face of the upper substrate of the liquid crystal panel and the segment side connector electrode terminal section 22a are positioned, then they are thermally pressed from the display face side (upper side) to connect an electrode. The liquid crystal panel is not required to be reversed to connect the electrode.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting electrodes of a liquid crystal display panel, and more particularly to a method of connecting electrodes of a liquid crystal display panel that facilitates connection and eliminates the problem of disconnection of flexible circuit boards.

0002

[Prior Art] This type of liquid crystal display device is shown in FIGS. 1 and 2.
As shown in (a) and (b), two upper and lower substrates 11a,
A liquid crystal panel main body 10 comprising a liquid crystal 14 sandwiched between 11b and 11b.
and an external drive circuit (
(not shown).

[0003] Liquid crystal driving electrodes (segment electrodes and common electrodes) in the form of stripes orthogonal to each other are formed on the liquid crystal holding surfaces of the two upper and lower substrates 11a and 11b. Then, in order to use one end of each liquid crystal drive electrode as a connection terminal with an external drive circuit, one side of each substrate is made to protrude from the other substrate to form an exposed part, and the liquid crystal drive on this exposed part is The electrodes for use are electrode terminal portions (segment electrode terminal portion 12a and common electrode terminal portion 12b).

[0004]The structure is such that a connector terminal portion formed on a flexible circuit board is connected to each of the electrode terminal portions 12a and 12b by thermocompression bonding (heat sealing).

[0005]

However, in the above-mentioned liquid crystal display device, as shown in FIG. 1, the orientations of the segment electrode terminal portion 12a and the common electrode terminal portion 12b are vertically opposite. Therefore, in order to connect the connector terminal part of the flexible circuit board to the electrode terminal part, after connecting one electrode terminal part and the connector terminal part, turn the liquid crystal panel upside down, and connect the other electrode terminal part and the connector terminal part. This requires a complicated connection process such as connecting the terminal portions, and this connection process has the problem of impairing the alignment of the liquid crystal panel.

Furthermore, since the flexible circuit board is attached to the back surface of the liquid crystal panel, the connector terminal portion of the flexible circuit board must be routed to the back surface of the liquid crystal panel. For this reason, there is a technique (Japanese Patent Laid-Open No. 60-205427) in which the connector part connected to the common side electrode terminal of the liquid crystal panel is bent in a reverse U-shape, or the bent part is inserted into the concave part of the reinforcing plate. Storage technology (Japanese Patent Laid-Open No. 1983)
-13523) etc. have been proposed. However, in all of the above-mentioned conventional technologies, large strain occurs at the bent part of the connector part of the flexible circuit board, and there is a risk of wire breakage at this part. There is a problem that this is likely to occur, and display abnormalities occur frequently.

Furthermore, a flexible circuit board (FPC) is sandwiched between the upper frame and the lower frame that fix the liquid crystal panel, and the FPC and the electrodes of the liquid crystal panel are connected by a protrusion bent around the lower frame. A method (Utility Model Publication No. 57-90424) has also been proposed, but this method
Since C is clamped and fixed, dimensional accuracy is required for both the upper frame and the lower frame, and there is also the problem that the number of parts such as the upper frame, the lower frame, and the holding member increases. Furthermore, when used for a long period of time, there is a problem that the protrusion at the part where the electrodes are connected becomes deformed, reducing the pressure contact strength and causing connection failure.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a method for connecting electrodes of a liquid crystal display panel, which allows easy connection and eliminates the risk of disconnection of the flexible circuit board.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the method for connecting electrodes of a liquid crystal display panel of the present invention provides a method for connecting the electrodes of a liquid crystal display panel by sandwiching a liquid crystal between two flexible substrates. A method of connecting an electrode terminal part of a liquid crystal drive electrode group formed on a substrate and a connector terminal part of a flexible circuit board, the method comprising: connecting an electrode terminal part of a liquid crystal driving electrode group formed on a substrate with a connector terminal part of a flexible circuit board, the method comprising: At least one elongated hole is formed, the connector terminal portion of the flexible circuit board is inserted into the elongated hole from the back side of the reinforcing plate, and a band-shaped portion on the front side of the reinforcing plate is formed along the outer edge of the elongated hole. , fixing the connector terminal part so that the connection terminal faces upward, and then aligning the electrode terminal part on the back side of the upper flexible board and the connector terminal part of the flexible circuit board,
Next, these terminals are connected by thermocompression bonding from the surface side of the upper flexible circuit board, and preferably, the connector terminals of the flexible circuit board are bonded to the strip-shaped portion on the surface side of the reinforcing plate. The fixing strength is such that the connector terminal portion of the circuit board can be easily peeled off from the reinforcing plate after the terminal portions are connected by thermocompression bonding.

The present invention will be explained in detail below. The present invention relates to a method for connecting electrode terminal portions formed on each flexible substrate of a liquid crystal panel body and connector terminal portions formed on a flexible circuit board.

Here, the liquid crystal panel main body 10 has a liquid crystal material 14 sandwiched between two upper and lower flexible substrates 11a and 11b, as shown in FIGS. 1 and 2(a) and (b). It is configured. Striped transparent electrodes for driving the liquid crystal are formed on the liquid crystal holding surface side of each flexible substrate 11a, 11b, and the flexible substrates 11a, 11b are arranged so that these striped transparent electrodes cross each other at right angles. 11b is arranged. Then, a voltage is applied to each unit pixel in a matrix formed by the upper and lower striped transparent electrodes crossing each other to perform liquid crystal display. Note that the transparent electrode is not limited to a matrix structure, and may be a segment display type electrode.

Each of the flexible substrates 11a and 11b has one side thereof protruding from the other substrate to form an exposed portion, and transparent electrodes 13a and 13b are exposed on the exposed portion.
Certain portions are defined as a segment electrode terminal portion 12a and a common electrode terminal portion 12b, respectively.

The flexible substrates 11a and 11b are not particularly limited as long as they are made of flexible and transparent materials. For example, plastic films such as polyethylene terephthalate (PET), polyether sulfone (PES), and polycarbonate (PC) can be used. The thickness of the substrate is usually preferably 10 μm to several mm.

[0014] An electrode is provided on one side of each of the flexible substrates 11a and 11b, but the material for forming the electrode is not particularly limited as long as it is a transparent material. For example, transparent electrodes such as ITO films made of indium oxide or a mixture of indium oxide and tin oxide are suitable, and these are usually deposited on the above-mentioned flexible substrates.

A known liquid crystal material can be used as the liquid crystal material 14 sandwiched between the flexible substrates 11a and 11b.

As shown in FIG. 3, a flexible circuit board (FPC) 20 has a wiring pattern 21 formed on a thin film (sheet), and a segment side connector terminal portion 22a and a wiring pattern 21 are formed at the ends of this wiring pattern 21. A common side connector portion 22b is formed. A liquid crystal driving LSI 24 is connected to the other side of the wiring pattern 21, and the liquid crystal driving LSI 24 is connected to a control circuit (not shown) via a sheet-like connector 25. The material for forming the flexible circuit board 20 is preferably a polyester film, a polyimide film, etc., which have excellent flexibility and heat resistance. Moreover, it is preferable that the thickness of the flexible circuit board 20 is 0.1 mm or less.

The material for forming the wiring pattern (conductive layer) 21 is not particularly limited as long as it has conductivity, but in order to prevent wire breakage even when the flexible circuit board is folded, silver, graphite, and metal are used. It is preferable to use single conductive particles such as or a blend of these particles dispersed in a flexible polymeric resin binder. Examples of methods for forming the wiring pattern include screen printing, photolithography, and the like. It is preferable to form a hot melt resin layer as an adhesive layer on the connection terminals 23a and 23b of the wiring pattern 21 so that the connection can be made by thermocompression bonding. When the hot melt layer is not formed on the connecting terminals 23a, 23b, the electrode terminal parts 12a, 12b and the connector electrode terminal parts 22a, 22
An anisotropic conductive film is interposed between the electrodes b and the electrodes are connected to each other by thermocompression bonding. In this case, the anisotropic conductive film is attached to the connector electrode terminal portion 22a in advance.
, 22b side.

The reinforcing plate 30 is attached to the back surface of the liquid crystal panel body. The shape of this reinforcing plate 30 is made to match the shape of the liquid crystal panel body, and may be flat or curved. The material of the reinforcing plate 30 is not particularly limited as long as it is a rigid material, and for example, a metal plate or a heat-resistant plastic is used. As a heat-resistant plastic, 150
It is preferable that thermal deformation does not occur when stress is applied at ℃ for 5 seconds. Further, a heat-resistant diffusion plate may be used as the reinforcing plate.

As shown in FIGS. 4A and 4B, a long hole 31 is formed inside one end edge of the reinforcing plate 30 along one end edge of the reinforcing plate 30. Insert the connector terminal part of the flexible circuit board into the connector terminal part of the flexible circuit board.

Next, the procedure for implementing the method for connecting electrodes of a liquid crystal panel according to the present invention will be explained. First, as shown in FIG. 4(b), the segment side connector terminal portion 22a of the flexible circuit board 20 is inserted into the elongated hole 31 of the reinforcing plate 30, and the reinforcing plate surface is formed along the outer edge of the elongated hole 31. The connector is lightly fixed to the side band-shaped portion 32 with the connecting terminal 23a facing upward. The portion of the flexible circuit board 20 that is not inserted through the elongated hole 31, that is, the portion other than the connector terminal portion 22a, is fixed to the back surface of the reinforcing plate 30. All fixing is done using double-sided adhesive tape or adhesive.

Next, the upper flexible substrate 11 of the liquid crystal panel
After aligning the electrode terminals 13a of the segment electrode terminal portions 12a formed on the reinforcing plate 30 with the connecting terminals 23a of the segment side connector terminal portions 22a fixed on the reinforcing plate 30, the liquid crystal panel main body 10 is placed on the reinforcing plate 30. Temporarily fix it with adhesive tape, etc. This temporary fixing can prevent deformation of the liquid crystal panel, and can also prevent the orientation of the liquid crystal from being disturbed when connecting the electrodes.

Next, thermocompression bonding (heat sealing) is performed from the surface side of the upper flexible substrate using a heating head, as shown in FIG.
As shown in (a), the segment electrode terminal 13a and the connecting terminal 23a of the segment side connector terminal portion 22a are electrically and mechanically connected.

Note that during this thermocompression bonding, the upper flexible substrate 11a is bent downward and connected to the connection terminal 23 of the segment side connector terminal portion 22a. At this time, the bonding strength between the band-shaped portion 32 on the front side of the reinforcing plate 30 and the segment-side connector terminal portion 22a is made weak, and after the connection by thermocompression bonding, from the band-shaped portion 32 on the front side of the reinforcing plate 30 to the segment side It is preferable that the connector terminal portion 22a be easily peeled off and the upper flexible substrate 22a returned to its original planar state. This is to prevent stress (deformation) from being applied to the liquid crystal panel.

Next, as shown in FIGS. 5 and 6(b), the electrode terminals of the common electrode terminal portion 12b formed on the lower flexible substrate 11b of the liquid crystal panel and the printed circuit board 2 are connected.
After aligning the connection terminal of the common side connector terminal part 22b of No. 0 with the connection terminal, thermocompression bonding is performed with a heating head from the common side connector terminal part 22b side located on the upper side, and the common electrode terminal and the common side connector terminal part are bonded together using a heating head. The connecting terminal 22b is electrically and mechanically connected. As shown in FIGS. 7(a) and 7(b), a long hole 34 is formed inside one end edge of the reinforcing plate 30, and the common side connector terminal portion 22b is
It is also possible to insert the long hole 34 into the elongated hole 34.

As described above, in the method of the present invention, both the segment side and common side electrodes can be bonded by thermocompression from the display surface side (upper side) of the liquid crystal panel, and there is no need to turn the panel over, making connection easy. .

After the above connection, a polarizing plate is attached to the liquid crystal panel main body 10, and a reflecting plate or a backlight is further attached to obtain a reflective or transmissive type liquid crystal display device. In this case, since the liquid crystal panel main body 10 and the reinforcing plate 30 and the reinforcing plate 30 and the flexible circuit board 20 are lightly attached, they are peeled off as appropriate and fixed again at an appropriate position.

[0027]

[Examples] The present invention will be explained in more detail with reference to Examples below. Example 1 ■ In FIG. 1, the liquid crystal panel main body 10 is a pair of upper and lower polyether sulfone (PES) substrates 11 on which striped ITO transparent electrodes 13a and 13b are formed.
A matrix structure in which liquid crystal 14 was sealed between a and 11b was used. The PES substrate was a transparent substrate with a thickness of about 100 μm. In addition, the sandwiched liquid crystal 1
The orientation operation in step 3 was carried out according to a known orientation treatment method. As the liquid crystal material, a ferroelectric liquid crystal (number average molecular weight of about 3000) having a structure shown in the following formula (1) was used.

[0028]

[Chemical formula 1]

Further, the phase transition behavior (phase transition temperature) of the ferroelectric liquid crystal shown in the above equation (1) is shown in the following equation (2). Here, g represents a glass state, SmC* represents a chiral smectic C layer, SmA represents a smectic A layer, and Iso represents an isotropic phase.

[0030]

[Case 2]

(2) As the reinforcing plate 30, as shown in FIG. 4(a), an epoxy resin substrate having a size corresponding to the shape of the liquid crystal panel 10 was used. Long hole 31 on reinforcing plate 30
The width of the long hole was approximately 2 mm, and the length of the long hole was formed to correspond to the length of the segment side connector portion of the flexible circuit board 20.

■ As shown in FIG. 4(b), the reinforcing plate 3
Insert the segment side connector terminal part 22a of the flexible circuit board 20 into the long hole 31 of 0 from the back side of the reinforcing plate 30, and insert the connector terminal part 23a of the connector into the strip part 32 on the front side of the reinforcing plate 30 so that it faces upward. It was lightly attached with double-sided adhesive tape. The portion of the flexible circuit board 20 other than the connector portion was fixed to the back surface of the reinforcing portion 30 with double-sided adhesive tape.

■Next, the segment electrode terminal portion 12 formed on the upper flexible substrate 11a of the liquid crystal panel 10
After aligning the electrode terminals 13a on the reinforcing plate 30 with the connecting terminals 23a of the segment side connector terminal portions 22a fixed on the reinforcing plate 30, the liquid crystal panel 10 was fixed on the reinforcing plate 30 with adhesive tape or the like.

■ Next, as shown in FIG. 6(a), thermocompression bonding (heat sealing conditions: 150° C., 3
0 Kg/cm2, 5 seconds) to electrically and mechanically connect the electrode terminal 13a of the segment electrode terminal portion 12a and the connecting terminal 23a of the segment side connector terminal portion 22a via the hot melt adhesive layer on the connecting terminal 22a. connected to.

■ Next, the common electrode terminal portion 12b formed on the lower flexible substrate 11b of the liquid crystal panel 10 and the common side connector terminal portion 2 of the flexible circuit board 20 are connected.
2b, the electrodes were connected by thermocompression using a thermocompression bonding machine in the same manner as described above from the common side connector terminal portion 22b located on the upper side.

■ As shown in FIGS. 4(b) and 4(c), polarizing plates 40a and 40 are provided on the front and back surfaces of the liquid crystal panel body 10 so that the contrast when the electric field is turned on/off is maximized.
b was installed. Furthermore, a reflective plate 50 was disposed between the polarizing plate 40b and the reinforcing plate 30 to obtain a reflective liquid crystal display device.

Embodiment 2 As the reinforcing plate 30, as shown in FIGS. 6(a) and (c),
A flexible display device was manufactured in the same manner as in Example 1, except that a central part was hollowed out and a diffuser plate 33 was fitted therein, and a backlight 60 was provided on the back side of the reinforcing plate 30 to make a transmissive liquid crystal display device. The electrode terminal portions 12a, 12b formed on the flexible circuit boards 11a, 11b were connected to the connector electrode terminal portions 22a, 22b of the flexible circuit board 20. In this case, as shown in FIG. 5(b), the flexible circuit board 20 temporarily adhered to the back surface of the reinforcing plate 30 is
It was peeled off from the backlight 60 and adhesively fixed to the back surface of the backlight 60.

Example 3 The electrode terminal portions were connected in the same manner as in Example 2 except that a diffusion plate was used as the reinforcing plate 30 as shown in FIG.

As is clear from the above Examples 1 to 3, according to the method for connecting electrodes of a liquid crystal display panel of the present invention, the electrodes can be easily connected without reversing the panel, and the polarized light after the electrodes are connected is Installation of plates, reflectors, etc. can be done smoothly.

[0040]

As described above, according to the method for connecting electrodes of a liquid crystal display panel of the present invention, electrodes can be connected easily and there is no possibility of disconnection of the flexible circuit board.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a liquid crystal panel main body.

[Fig. 2] Fig. 2(b) is a cross-sectional view taken along the line A-A in Fig. 1;
) is a sectional view taken along the line B-B in FIG. 1.

FIG. 3 is a plan view showing an example of a flexible circuit board.

FIG. 4 is a diagram showing a state in which the reinforcing plate and the flexible circuit board are fixed, FIG. 4(a) is a perspective view, and FIG. 4(b) is a diagram of FIG.
It is a sectional view taken along the line CC in (a).

FIG. 5 is a perspective view showing a connection state between an electrode terminal part and a connector electrode terminal part.

6(b) is a sectional view taken along line DD in FIG. 5(a), and FIG. 6(b) is a sectional view taken along line EE in FIG. 5. FIG.

FIG. 7 is a diagram showing an example in which two elongated holes are formed in the reinforcing plate, FIG. 7(a) is a perspective view, and FIG. 7(b) is the same as FIG. 7(a).
FIG.

FIG. 8 is a diagram showing another embodiment of the method of the present invention, and FIG.
7(a) is a perspective view showing another example of the reinforcing plate, and FIG. 7(b) is a sectional view showing a connection state in a liquid crystal display device equipped with a backlight.

FIG. 9 is a partial sectional view showing an example in which a diffusion plate is used as a reinforcing plate.

[Explanation of symbols]

10...Liquid crystal panel body 11a...Upper flexible substrate 11b...Lower flexible substrate 12a...Segment electrode terminal section 12b...Common electrode terminal section 13a...Segment electrode terminal 13b...Common electrode terminal 14...Liquid crystal material 20...Flexible circuit Substrate 22a...Segment side connector electrode terminal part 22b...Common side connector electrode terminal part 23a, 23b...Connection terminal 30...Reinforcement plates 31, 34...Elongated hole 32...Striped portions 40a, 40b...Polarizing plate 50...Reflector plate 60...Back light

Claims (3)

[Claims] [Claim 1] Electrode terminal portions of a liquid crystal drive electrode group formed on each flexible substrate of a liquid crystal panel body formed by sandwiching a liquid crystal between two flexible substrates, and connector terminals of a flexible circuit board. The connecting method includes forming at least one elongated hole inside one end edge of a reinforcing plate attached to the back surface of the liquid crystal panel main body, and connecting the connector terminal portion of the flexible circuit board to the back side of the reinforcing plate. At the same time, the connector terminal portion is inserted into the elongated hole, and the connector terminal portion is fixed to a band-shaped portion on the surface side of the reinforcing plate formed along the outer edge of the elongated hole with the connecting terminal facing upward. The electrode terminals on the back side of the flexible board are aligned with the connector terminals on the flexible circuit board, and then thermocompression bonding is performed from the front side of the upper flexible board to connect these terminals. A method for connecting electrodes of a liquid crystal display panel, characterized by the following. [Claim 2] The fixing strength of the connector terminal portion of the flexible circuit board to the strip-shaped portion on the front side of the reinforcing plate can be increased by easily connecting the connector terminal portion of the circuit board from the reinforcing plate after connecting the terminal portions to each other by thermocompression bonding. 2. The method for connecting electrodes of a liquid crystal display panel according to claim 1, wherein the method has a strength that allows peeling. [Claim 3] A claim characterized in that the elongated hole through which the connector terminal portion of the flexible circuit board is inserted is comprised of an elongated hole through which the segment side connector terminal portion is inserted and an elongated hole through which the common side connector terminal portion is inserted. Item 2. A method for connecting electrodes of a liquid crystal display panel according to item 1 or 2.