JPH07175072A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To repair a substrate having defects or reuse a substrate by forming an adhesive layer of a thermoplastic adhesive and a non-thermoplastic adhesive as an adhesive part. CONSTITUTION:A first oriented film 5 and second oriented film 6 are disposed opposedly to each other at a specified interval in such a manner that the rubbing directions of respective films cross each other orthogonally, and a spacer 8 to maintain the interval between the first substrate 1 and second substrate 2 is interposed between the substrates. Then, fringe parts of the first substrate 1 and the second substrate 2 are adhered in two steps. In the first step, a thermoplastic adhesive 9 is used to adhere the fringe parts of the first substrate 1 and the second substrate 2 except a part of an injection port. Then, a liquid crystal compsn. 7 is injected between the main faces of the first substrate 1 and the second substrate 2 through the injection port, and the injection port is sealed. In the second step, a nonthermoplastic adhesive 10 is used in adjacently to the thermoplastic adhesive 9 used in the first step so that the fringe parts of the substrates 1, 2 are joined to each other to be completely covered with the adhesive 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly to bonding the peripheral edge of the substrate.

[0002]

2. Description of the Related Art In a liquid crystal display, a predetermined electrode pattern and an alignment film formed respectively on the main surfaces of a first substrate and a second substrate are arranged to face each other at a predetermined interval, and a first substrate and a second substrate are provided.
And a liquid crystal composition enclosed in a substrate at a predetermined interval. Then, by applying a predetermined voltage to this electrode, the liquid crystal molecules in the voltage application portion are changed,
It displays various characters, symbols and numbers.

Such a liquid crystal display is generally manufactured through the following steps. That is, first, a predetermined conductive electrode pattern is formed on the main surfaces of the first substrate and the second substrate. When displaying characters, symbols, numbers, etc., this electrode pattern is arranged in a matrix, and a pattern in which a switching element is arranged in a portion corresponding to each pixel is also included as a part of the electrode. Then, an alignment film is formed on these electrode patterns to complete the first substrate and the second substrate.

Next, the first substrate and the second substrate are opposed to each other at a predetermined interval with a spacer in between so that the respective electrode patterns are opposed to each other. Then, the peripheral portions of the first substrate and the second substrate are bonded with an adhesive. At this time, an injection port is provided in a part of the peripheral portion, and the liquid crystal composition is injected from the injection port after the bonding process of the peripheral portion is completed. Then, finally, the injection port is sealed to complete the liquid crystal display.

[0005]

Due to the constitution of such a liquid crystal display device, a display inspection is carried out by applying a predetermined voltage after the final sealing step is completed. Then, if any defect occurs in the display portion or the like, the entire liquid crystal display becomes defective. However, a thermosetting adhesive is usually used for adhering the peripheral portion of the substrate, and this thermosetting adhesive cannot be separated after the curing adhering to separate the first substrate and the second substrate. Can not. Therefore, the defective liquid crystal display is entirely discarded.

However, if the first substrate and the second substrate can be separated, some of them can be repaired depending on the degree of the defect. Further, even if repair is impossible, the substrate glass can be reused. Therefore, repairing and reusing a defective substrate has great cost advantages.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid crystal display and a method of manufacturing the same, which enables repair of a defective substrate and reuse of the substrate.

[0008]

According to the present invention, there are provided a first substrate and a second substrate having at least a predetermined electrode pattern and an alignment film formed thereon, and the electrode patterns of the first substrate and the second substrate. A liquid crystal composition that is arranged to face each other at a predetermined interval and is sealed in the facing interval between the first substrate and the second substrate,
A liquid crystal display comprising at least an adhesive portion for adhering the peripheral portions of the first substrate and the second substrate, wherein the adhesive portion comprises a bonding layer of a thermoplastic adhesive and a non-thermoplastic adhesive. And a step of forming at least an electrode pattern and an alignment film on the main surfaces of the first substrate and the second substrate, and arranging the main surfaces of the first substrate and the second substrate facing each other at a predetermined interval. The first substrate and the second substrate
In the method for manufacturing a liquid crystal display, which comprises at least a step of adhering a peripheral portion of the substrate, a step of injecting a liquid crystal composition from the injection port, and a step of sealing the injection port, the first substrate And the step of adhering the peripheral portion of the second substrate is at least the first adhering step using a thermoplastic adhesive,
It is a method of manufacturing a liquid crystal display, which comprises a second bonding step using a non-thermoplastic adhesive.

[0009]

In the present invention, the bonding step for joining the peripheral portions of the first substrate and the second substrate is performed at least twice. First, in the first bonding step, the peripheral edges of the first substrate and the second substrate are bonded using a thermoplastic adhesive. In the second and subsequent bonding steps, the peripheral portions of the first substrate and the second substrate are bonded using a non-thermoplastic adhesive so as to be adjacent to the thermoplastic adhesive applied in the first bonding step. To do.

The thermoplastic adhesive used in the first bonding step has a property that the adhesive starts to soften when the heating temperature exceeds a certain value. Since the adhesive force is extremely reduced when the adhesive starts to soften, it is possible at this time to easily separate and separate the first substrate and the second substrate.

Therefore, the first using a thermoplastic adhesive
In the second bonding step, the display inspection is performed by applying a predetermined voltage to the liquid crystal display without softening the thermoplastic adhesive by heating. Then, if any defect is generated in this display inspection, it is heated above the softening point of the thermoplastic adhesive, and the first substrate and the second substrate are separated from each other in the subsequent repair or reuse process. Move. The thermoplastic adhesive can be easily dissolved and removed from the substrate after peeling with water or a solvent.

Next, the liquid crystal display device having no defect in the display inspection has a thermoplastic adhesive applied in the first bonding step as the second bonding step after the first bonding step. The peripheral portions of the first substrate and the second substrate are bonded to each other by using a non-thermoplastic adhesive so that they are adjacent to each other. this is,
This is because the thermoplastic adhesive used in the first bonding step has insufficient adhesive strength to water or a solvent, so that the bonding of the substrates is finally reliable.

[0013]

EXAMPLES Examples of the present invention will be described below. FIG. 1 shows the structure of a liquid crystal display device up to the middle of the manufacturing process of the embodiment of the present invention. In FIG. 1, a first conductive electrode 3 having a predetermined pattern is formed on the main surface of a first substrate 1, a first alignment film 5 is formed thereon, and alignment treatment such as rubbing is performed. There is. On the other hand, a second conductive electrode 4 having a predetermined pattern is formed on the main surface of the second substrate 2, a second alignment film 6 is formed on the second conductive electrode 4, and alignment treatment such as rubbing is performed.

The first substrate 1 and the second substrate 2 thus completed are, for example, the first substrate in the case of a TN type liquid crystal display.
Of the first alignment film and the second alignment film 6 are arranged facing each other at a predetermined interval so that the rubbing directions of the first alignment film and the second alignment film 6 are orthogonal to each other, and a spacer 8 for maintaining a predetermined interval between the first substrate 1 and the second substrate 2.
Is sandwiched between both substrates. Up to this point, the manufacturing process of the conventional liquid crystal display is the same, and various both substrates are prepared corresponding to the target liquid crystal display.

Next, the step of adhering the peripheral portions of the first substrate 1 and the second substrate 2 is started. First, as the first bonding step, the peripheral edges of the first substrate 1 and the second substrate 2 are bonded together using a thermoplastic adhesive 9 leaving some injection ports (not shown). As the thermoplastic adhesive 9, for example, an adhesive made of polyvinyl butyral is used. The softening temperature of this thermoplastic adhesive is approximately 170 ° C.

Then, after the liquid crystal composition 7 is injected from the injection port between the main surfaces of the first substrate 1 and the second substrate 2, the injection port is sealed. Since the liquid crystal display can be electrically operated in this state, a display test of the liquid crystal display is performed by applying a voltage of a predetermined driving condition.

As a result of the display inspection, the liquid crystal display having some display defect is heated to 170 ° C. or higher, which is the softening temperature of the thermoplastic adhesive 9 made of polyvinyl butyral, and then the first substrate 1 and the first substrate 1 The two substrates 2 are separated. The separated substrate is washed with a solvent to remove the adhesive, the liquid crystal composition, the spacers, and the like, and then the substrate is repaired or reused.

Next, the second bonding step of the liquid crystal display which has become a non-defective product without display defects is performed as shown in FIG.
In FIG. 2, members similar to those in FIG. 1 are denoted by the same reference numerals and their description will be omitted. In the second bonding step, the first
A non-thermoplastic adhesive 10 is used so as to be adjacent to the thermoplastic adhesive 9 that has been bonded in the second bonding step, and the first substrate 1 and the second substrate 2 are bonded so as to completely cover the peripheral portions thereof. .

As the non-thermoplastic adhesive 10, a thermosetting adhesive made of epoxy resin was used. The temperature at which this thermosetting adhesive is thermoset is approximately 150 ° C. Therefore, since the softening temperature of the thermoplastic adhesive 9 used in the first bonding step is sufficiently lower than about 170 ° C., the softening of the thermoplastic adhesive 9 during heat curing does not occur and the first substrate 1
Therefore, deformation such as displacement of the second substrate 2 does not occur. Further, as the non-thermoplastic adhesive 10, any adhesive having durability against water or a solvent may be used, and various adhesives such as an ultraviolet curable adhesive can be used.

[0020]

As described above, according to the present invention, it is possible to select a liquid crystal display having a display defect, separate and separate both substrates of these defective liquid crystal displays, and repair or reuse them. As a result, it is possible to reduce the cost in the manufacturing process and provide a highly reliable liquid crystal display.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a liquid crystal display partway through the manufacturing process of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of a liquid crystal display that has completed the manufacturing process according to the embodiment of the invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st substrate 2 ... 2nd substrate 3 ... 1st conductive electrode 4 ... 2nd conductive electrode 5 ... 1st alignment film 6 ... 2nd alignment film 7 ... Liquid crystal composition 8 ... Spacer 9 ... Thermoplastic adhesive 10 ... Non-thermoplastic adhesive

Claims (2)

[Claims] 1. A first substrate and a second substrate having at least a predetermined electrode pattern and an alignment film formed thereon, and the first substrate.
Liquid crystal composition in which the electrode patterns of the first substrate and the second substrate are arranged to face each other at a predetermined interval, and the liquid crystal composition is sealed in the facing interval of the first substrate and the second substrate, and the first substrate and the second substrate. A liquid crystal display, comprising at least an adhesive portion for adhering a peripheral portion of a substrate, wherein the adhesive portion comprises a bonding layer of a thermoplastic adhesive and a non-thermoplastic adhesive. 2. A step of forming at least an electrode pattern and an alignment film on the main surfaces of the first substrate and the second substrate, and the first step.
A main surface of the second substrate and a main surface of the second substrate are opposed to each other at a predetermined distance, and the peripheral portions of the first substrate and the second substrate are bonded to each other while leaving a part of the injection port; In the method for manufacturing a liquid crystal display, which includes at least a step of injecting a composition and a step of sealing the injection port, at least the step of adhering the peripheral portions of the first substrate and the second substrate is thermoplastic. A method for manufacturing a liquid crystal display, comprising a first bonding step using an adhesive and a second bonding step using a non-thermoplastic adhesive.