JP2003287768A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying a uniform image. <P>SOLUTION: A liquid crystal panel is formed by sticking one member wherein a transparent electrode 12 and alignment layer (not figured) are successively formed on a transparent substrate 1 and the other member wherein a transparent electrode 12 and an alignment layer (not figured) are successively formed on a transparent substrate 3 to each other by using a sealing member 2. In the liquid crystal display device, an adhesive member 4 is applied on the transparent substrate 1 of the liquid crystal panel, a driving IC 6 for driving the display panel is fixed onto the adhesive member 4 and the softening point of the sealing member 2 is set to be equal to or higher than the softening point of the adhesive member 4. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a liquid crystal display device equipped with a driving IC.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used not only for small or medium-sized portable information terminals and notebook computers, but also for large and high-definition monitors. A conventional liquid crystal display device will be described with reference to FIGS.

FIG. 4 is a plan view of the liquid crystal display device.
FIG. 6 is a sectional view taken along a section line bb ′ of the main part B of the apparatus shown in FIG. 4.

One member in which a transparent electrode 12 and an alignment film (not shown) are sequentially formed on a transparent substrate 1 made of glass or the like, and a transparent electrode 13 and an alignment film (not shown) on a transparent substrate 3 made of glass or the like. And the other member on which the spacer 7 is formed so that the transparent electrode 12 and the transparent electrode 13 are orthogonal to each other, the spacer 7 is dispersed between the one member and the other member, and a thermosetting seal is formed. The members 14 are attached to each other, and a uniform force is applied to the outer surfaces of the transparent substrate 1 and the transparent substrate 3 to uniformly maintain the inter-substrate gap between the one member and the other member.

Then, by throwing into an oven or the like to fix the gap between the substrates of the one member and the other member,
A thermosetting reaction is caused in the seal member 14, and the temperature is returned to room temperature to completely cure the seal member 14, and the liquid crystal 11 is applied to a region surrounded by the cured seal member 14, one member and the other member. Intervene.

According to the above structure, the transparent electrode 12 and the transparent electrode 13 are orthogonal to each other to form the display region 10, and the transparent electrode 12 is extended to the non-display region 9 on the transparent substrate 1 to form the transparent electrode. In 13, both transparent substrate 1 and transparent substrate 3
It is transferred onto the transparent substrate 1 through a conductive member or the like provided between and and extends from there to the non-display area 9 on the transparent substrate 1.

Further, a thermosetting adhesive member 15 is attached to the non-display area 9 on the transparent substrate 1, and the driving IC 6 having electrode terminals is aligned and arranged on the adhesive member 15, and Then, the liquid crystal display device is put into an oven or the like, a thermosetting reaction is caused in the adhesive member 15 in accordance with this, and the adhesive member 15 is completely cured by returning the temperature to room temperature, so that the drive IC 15 and the transparent substrate 1 are separated. Stick to it.

After that, the electrode terminals of the driving IC 6 are connected to the transparent electrode 12 and the transparent electrode 13 by the bonding wire 5 made of gold, aluminum or the like, and the driving IC 6 is connected to the transparent electrode 12 and the transparent electrode 13. It is possible to provide a liquid crystal display device that displays an image as required by inputting a signal.

The sealing member 14 and the adhesive member 15 both start a curing reaction when the temperature is raised by applying heat. This temperature is set as a curing temperature, and the curing reaction is completed for a certain period of time to maintain the curing temperature.
Then, when the temperature is lowered to the softening point or lower, a cured product having a high elastic modulus is obtained. The softening point is a temperature at which the cured product is heated again to increase its temperature to a high temperature, and when a certain temperature is reached, the elastic modulus sharply decreases.

Thus, the liquid crystal display device in which the transparent substrate 1 and the driving IC 6 are fixed to each other is obtained through the above steps.

[0011]

However, according to the liquid crystal display device having the above structure, the display may be uneven in the vicinity of the driving IC 6 in the display area 10.

The present inventor has made earnest research in view of the above circumstances, and as a result, such a problem is solved by defining a softening point between the seal member and the adhesive member of the driving IC. I found that.

The present invention has been completed based on the above findings, and an object thereof is to provide a liquid crystal display device capable of uniform image display by setting the softening point of a seal member to be equal to or higher than the softening point of an adhesive member. It is in.

[0014]

A liquid crystal display device according to the present invention is one member in which a transparent electrode and an alignment film are sequentially formed on a substrate, and another member in which a transparent electrode and an alignment film are sequentially formed on another substrate. The member is bonded to the member via a seal member, and a liquid crystal layer is filled to form a display area, and a driving IC for applying a voltage to the transparent electrode is applied to a non-display area on the substrate of the one member as an adhesive member. In the liquid crystal display device fixed by means of, the softening point of the seal member is set to be equal to or higher than the softening point of the adhesive member.

In another liquid crystal display device of the present invention, the difference between the coefficient of thermal expansion of the sealing member and the coefficient of thermal expansion of the adhesive member is 2 ×.
It is characterized by being 10 ⁻⁶ or less.

According to the conventional liquid crystal display device, the seal member 14 is first thermoset, and the adhesive member 15 is hardened in the second thermosetting step. Will also apply heat, and the adhesive member 1
5 reaches its softening point before 5 reaches its softening point, this sealing member 14 softens again, and when the device is removed from the oven and the temperature is lowered, the adhesive member 15 is completely cured first. Then, there is a problem in that the transparent substrate 1 is distorted due to subsequent curing of the seal member 14 and display unevenness occurs.

This problem will be described in more detail with reference to FIGS. 6 and 7.

FIG. 6 is a plan view of the liquid crystal display device showing the force generated on the transparent substrate, and FIG. 7 is a plan view of the liquid crystal display device having display unevenness.

After the second heat curing step, when the temperature of the liquid crystal display device is lowered, the adhesive member 15 is completely cured first, and then the seal member 14 is completely cured. The adhesive member 15 is first cured. Is completely cured, the force that shrinks inward with respect to the entire surface of the transparent substrate 1 as shown in FIG.
In the area of P, the area of P, and the area of Q, the force in the direction of the arrow is remarkably generated.

In other words, the contraction in the Q region with respect to the contraction of the substrate occurring in the entire transparent substrate 1 is caused by the seal member 14.
The transparent substrate 1 has the adhesive member 15 that is cured earlier.
The force apparently acts in the direction of the arrow with respect to the contraction that occurs in the whole. Along with this, a difference occurs in the contraction of the transparent substrate 1 between the region S near the driving IC 6 and the region P not near the driving IC 6. This becomes more remarkable as the driving IC 6 gets closer to the display area 10.

Therefore, the substrate surface of the transparent substrate 1 becomes non-uniform, and if the temperature of the device is lowered, the sealing member 1
4 is completely cured, and accordingly, the gap between the transparent substrate 1 and the transparent substrate 3 is fixed with unevenness occurring, and display unevenness X occurs as shown in FIG.

With respect to the occurrence of such display unevenness, according to the liquid crystal display device of the present invention, the softening point of the seal member 2 is set to be equal to or higher than the softening point of the adhesive member 4, so that the adhesive member 4 is thermoset. When the temperature of the device is lowered, the adhesive member 4 is not cured before the sealing member 2, and the substrate surface of the transparent substrate 1 becomes uniform, so that a good image display can be obtained.

[0022]

DETAILED DESCRIPTION OF THE INVENTION A liquid crystal display device of the present invention will be described below with reference to FIGS.

FIG. 1 is a plan view of the liquid crystal display device.
FIG. 2 is a sectional view taken along a section line aa ′ of the main part A of the apparatus shown in FIG. FIG. 3 is a cross-sectional view showing the curing of the adhesive member before and after being placed in an oven.

FIG. 2 IT on a transparent substrate 1 made of glass or the like
One member in which a transparent electrode 12 made of O or the like and an alignment film (not shown) are sequentially formed, and a transparent electrode 13 made of ITO or the like and an alignment film (not shown) on a transparent substrate 3 made of glass or the like.
And the other member sequentially formed with are aligned such that the transparent electrode 12 and the transparent electrode 13 are orthogonal to each other, the spacer 7 is dispersed between the one member and the other member, and the epoxy-based thermosetting The seal member 2 is used for bonding, and a uniform force is applied to the outer surfaces of the transparent substrate 1 and the transparent substrate 3 to hold the inter-substrate gap between one member and the other member as required.

Then, by throwing in an oven or the like to fix the inter-substrate gap between the one member and the other member,
The seal member 2 is accelerated by a heat curing reaction, and after the seal member 2 completely undergoes a curing reaction, it is returned to room temperature to cure the seal member 2 and is surrounded by the seal member 2, one member and the other member. The liquid crystal 11 is interposed in the area.

According to the above structure, the transparent electrode 12 and the transparent electrode 13 are orthogonal to each other to form the display region 10, and the transparent electrode 12 is extended to the non-display region 9 on the transparent substrate 1 to form the transparent electrode. In 13, both transparent substrate 1 and transparent substrate 3
It is transferred onto the transparent substrate 1 through a conductive member (not shown) provided between the transparent substrate 1 and the transparent substrate 1, and extends from there to the non-display area 9 on the transparent substrate 1.

Further, an adhesive member 4 having a softening point equal to or lower than the softening point of the thermosetting seal member 2 is attached to the non-display area 9 on the transparent substrate 1, and a drive having an electrode terminal on the adhesive member 4 is driven. The positioning IC 6 is arranged and arranged, the liquid crystal display device is put into an oven or the like, a thermosetting reaction is caused in the adhesive member 4, and the adhesive member 4 is completely cured by returning to room temperature. The driving IC 6 and the transparent substrate 1 are fixed to each other.

Preferably, when the adhesive member 4 is heat-cured in an oven, the liquid crystal expanded by heat as an upper limit temperature is expanded by an expansion pressure from a region surrounded by the seal member 2, one member and the other member. It is recommended to guarantee the temperature that does not leak as the upper limit.

In this curing step, bubbles are introduced into the adhesive member 4 when the driving IC 6 is mounted. When the adhesive member 4 is thermally cured in an oven, the bubbles are released to the outside as shown in FIG. By heating up to this, the adhesion between the transparent substrate 1 and the driving IC 6 can be enhanced.

Thus, after fixing the driving IC 6 on the transparent substrate 1, the electrode terminals of the driving IC 6 and the transparent electrode 1 are fixed.
2 and the transparent electrode 13 are connected by a bonding wire 5 made of gold, aluminum or the like, and a driving IC 6
It is possible to provide a liquid crystal display device that displays an image by inputting a signal from the transparent electrode 12 to the transparent electrode 13.

According to the present invention, preferably the sealing member 2
It is preferable to reduce the difference in the coefficient of thermal expansion between the adhesive member 4 and the adhesive member 4.

The seal member 2 and the adhesive member 4 are hardened by heat. The thermal expansion coefficients of both members are the transparent substrate 1.
Have a great influence on. That is, when the adhesive member 4 is thermoset, the thermal expansion of the transparent substrate 1 made of a glass material and the thermal expansion of the sealing member 2 and the adhesive member 4 made of an epoxy resin have a large difference. , Transparent substrate 1
Both the part where the upper seal member 2 is attached and the part where the adhesive member 4 is attached are likely to be distorted.

Therefore, by equalizing the thermal expansion coefficients of the seal member 2 and the adhesive member 4, the expansion of the transparent substrate 1 in the mounting portion of the driving IC 6 and the sealing on the transparent substrate 1 near the mounting portion of the driving IC 6 are performed. The difference from the expansion of the transparent substrate 1 at the attachment portion of the member 2 becomes small, and the transparent substrate 1 becomes more uniform. Along with this, the transparent substrate 1 and the transparent substrate 3
The gap between the substrates can be made more uniform, and a higher quality liquid crystal display device can be provided.

According to experiments conducted repeatedly by the present invention, if the difference between the coefficient of thermal expansion of the seal member 2 and the coefficient of thermal expansion of the adhesive member 4 is 2 × 10 ⁻⁶ or less, a liquid crystal display device without display unevenness is obtained. I got it.

As a concrete example of the liquid crystal display device having no display unevenness, the coefficient of thermal expansion of the seal member 2 is 7 × 10 ^−6.
And the thermal expansion coefficient of the adhesive member 4 is 5 × 10 ⁻⁶ .

It is desirable that the softening point of the seal member 2, the adhesive member 4, etc. be higher than the upper limit temperature of use for fulfilling the function of the liquid crystal, so that problems such as liquid crystal leakage will not occur.

Thus, according to the liquid crystal display device of the present invention having the above structure, the softening point of the seal member 2 is set to be equal to or higher than the softening point of the adhesive member 4, so that the liquid crystal display device is cured in the step of curing the adhesive member 4. When the temperature of the adhesive member 4 is cured, the sealing member 2 is simultaneously or first cured, and the adhesive member 4 is subsequently cured, so that the transparent substrate 1 in the display region 10 is simultaneously or before the adhesive member 4 is cured. Since the contraction of the transparent substrate 1 in the drive IC 6 mounting portion close to the display area 10 is fixed to the seal member 2, the contraction of the transparent substrate 1 in the portion of the display area 10 and the display area 10 are reduced. The nonuniformity of the transparent substrate 1 caused by the difference between the contraction of the transparent substrate 1 in the mounting portion of the driving IC 6 close to is eliminated, and as a result, the inter-substrate gap between the transparent substrate 1 and the transparent substrate 3 becomes uniform. Is lifting, it could provide a high-quality liquid crystal display device without display unevenness.

Further, since the difference in the coefficient of thermal expansion between the seal member 2 and the adhesive member 4 is made small, the expansion of the portion of the transparent substrate 1 to which the seal member 2 adheres and the portion of the transparent substrate 1 to which the adhesive member 4 adheres. The unevenness in display due to the difference between the expansion and the expansion was eliminated, and a higher quality liquid crystal display device could be provided.

[0039]

EXAMPLES Next, examples of the present invention will be described.

According to this example, a liquid crystal display device is produced with the structure shown in FIG. 1 and FIG.
The relationship between the difference in the softening point of the adhesive member 4 and the display unevenness was evaluated, and then the relationship between the display unevenness due to the difference in thermal expansion coefficient between the seal member 2 and the adhesive member 4 was evaluated.

In the evaluation of the display unevenness due to the difference in the softening points of the seal member 2 and the adhesive member 4 as a concrete configuration of the apparatus, the size of the image display area 10 is set to 10.4 inches and the seal member 2 is made of epoxy resin. By changing these conditions when synthesizing using acrylic resin or acrylic resin, five kinds of resin materials having a thermal expansion coefficient of 7.0 × 10 ⁻⁶ within a softening point range of 90 ° C. to 140 ° C. Was prepared, and the curing temperature was in the range of 100 ° C to 150 ° C.

Further, in the adhesive member 4, the seal member 2
In the same manner as above, a synthetic resin was prepared using an epoxy resin or an acrylic resin, having a softening point of 117 ° C., a curing temperature of 120 ° C. and a thermal expansion coefficient of 7.0 × 10 ⁻⁶ .

In the evaluation of display unevenness due to the difference in thermal expansion coefficient between the seal member 2 and the adhesive member 4, the size of the image display area 10 is set to 10.4 inches and the seal member 2 is synthesized as described above. Prepare a softening point of 140 ° C and a curing temperature of 150 ° C.
I prepared one.

Similarly, the adhesive member 4 was prepared in the same manner, with a softening point of 117 ° C., a curing temperature of 120 ° C. and a coefficient of thermal expansion of 5.0 × 10 ^−6.
And the thermal expansion coefficient of the adhesive member 4 is 1.0 × 10 ^{−6 to} 5.
It was set to 0 × 10 ⁻⁶ .

First, Table 1 shows the relationship between the softening points of the seal member 2 and the adhesive member 4 and the display unevenness due to the difference in curing temperature.

[0046]

[Table 1]

As shown in the table, ◯ indicates a good image display without display unevenness, and x indicates a display unevenness.

As is clear from the results shown in Table 1, good image display was obtained when the softening point of the adhesive member 4 was lower than the softening point of the seal member 2, but display unevenness was obtained for other samples. There was no good image display. That is, when the sealing member 2 had a softening point of 140 ° C. and a curing temperature of 150 ° C. and the sealing member 2 had a softening point of 119 ° C. and a curing temperature of 140 ° C., there was no display unevenness and a good image could be obtained.

Table 2 shows the relationship between display unevenness due to the difference in thermal expansion coefficient between the seal member 2 and the adhesive member 4.

[0050]

[Table 2]

As shown in the table, ∘ indicates a good image display without display unevenness, and x indicates a display unevenness.

As is clear from the results shown in Table 2, the difference in coefficient of thermal expansion between the seal member 2 and the adhesive member 4 is 1.0 × 10.
^-6 and 2.0 × 10 ^-6 , good images were obtained without display unevenness, but the difference in thermal expansion coefficient was 3.0 × 10 ^-6.
In the above cases, display unevenness occurred.

Therefore, in this embodiment, it is preferable to make the softening point of the adhesive member 4 lower than the softening point of the seal member 2 and set the difference between the thermal expansion coefficients of both to be 2.0 × 10 ⁻⁶ or less. A liquid crystal display device that displays an image is obtained.

[0054]

As described above, according to the liquid crystal display device of the present invention, by setting the softening point of the sealing member to be equal to or higher than the softening point of the adhesive member, shrinkage and display of the transparent substrate in the driving IC mounting portion can be achieved. The non-uniformity of the transparent substrate due to the difference in the contraction of the transparent substrate in the area is eliminated, whereby the inter-substrate gap between the transparent substrates is uniformly maintained, and a high-quality liquid crystal display device without display unevenness is provided. did it.

[Brief description of drawings]

FIG. 1 is a plan view of a liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional view of a main part A of the device shown in FIG. 1, taken along section line aa ′.

FIG. 3 is a cross-sectional view showing curing of an adhesive member before and after being put into an oven.

FIG. 4 is a plan view of a conventional liquid crystal display device.

5 is a cross-sectional view of a main part B of the device shown in FIG. 4, taken along section line bb '.

FIG. 6 is a plan view of a liquid crystal display device showing a force generated on a transparent substrate.

FIG. 7 is a plan view of a liquid crystal display device in which display unevenness occurs.

[Explanation of symbols]

1 ... Transparent substrate 2 ... Seal member 3 ... Transparent substrate 4 ... IC mounting seal member 5 ... Bonding wire 6 ... Drive IC

Continued front page    F term (reference) 2H089 KA17 LA49 NA45 QA06 TA03                       TA07 TA09                 2H092 GA59 GA60 MA32 MA37                 5C094 AA03 BA43 DA09 DB02 EB02                       EC01 FB01 GB01 HA08 JA01                       JA07                 5G435 AA01 BB12 EE37 EE44 HH20                       KK05 KK09 LL06 LL07 LL08

Claims (2)

[Claims] 1. A member having a transparent electrode and an alignment film sequentially formed on a substrate and another member having a transparent electrode and an alignment film sequentially formed on another substrate are bonded together via a seal member. A liquid crystal display device in which a liquid crystal layer is filled to form a display area, and a driving IC for applying a voltage to the transparent electrode is fixed to a non-display area on the substrate of the one member through an adhesive member, A liquid crystal display device, wherein a softening point of a member is set to be equal to or higher than a softening point of an adhesive member. 2. The liquid crystal display device according to claim 1, wherein the difference between the coefficient of thermal expansion of the seal member and the coefficient of thermal expansion of the adhesive member is 2 × 10 ⁻⁶ or less.