JP3173518B2 - Liquid crystal panel manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel used for a liquid crystal display, and more particularly to a seal for sealing substrates between substrates having different coefficients of thermal expansion such as a silicon substrate and a glass substrate. About technology.

2. Description of the Related Art In recent years, the demand for projection type liquid crystal displays has been increasing, and the development of projection type liquid crystal panels has been actively pursued. Research on liquid crystal panels using substrates is under way.

[0003]

2. Description of the Related Art FIG. 5 is a longitudinal sectional view showing a conventional method for thermally curing a sealant for a liquid crystal panel. 1 is a silicon substrate and 2 is a glass substrate.
, And a spacer ball 5 and liquid crystal are sealed in the internal space 4. Usually, a thermosetting resin is used as the adhesive 3h.

FIG. 6 is a perspective view showing a conventional liquid crystal panel sealing method in the order of steps. Reference numeral 1 denotes a silicon substrate on which switching thin film transistors are formed in a matrix. The adhesive 3h is screen-printed on the outer periphery of the silicon substrate 1 except for the liquid crystal injection port 6, and the silicon substrate 1 is overlapped with the glass substrate 2 on which silica balls are dispersed as shown in (2).

Next, in order to apply a uniform pressure between the substrates 1 and 2 to push the thermosetting adhesive 3h to a uniform thickness, the thermosetting adhesive 3h is put into a plastic bag 7 as shown in FIG. Exhaust
With the vacuum applied, the adhesive is thermally cured by heating. Thereafter, the liquid crystal panel is completed by taking out the vacuum pack bag 7 and injecting the liquid crystal through the liquid crystal inlet 6, and closing the liquid crystal inlet 6 with an adhesive as shown in (4).

[0006]

As described above, the adhesive 3h
As shown in FIG. 5 (3), the silicon substrate 1 and the glass substrate 2 are bonded together by thermosetting. There is a problem that the side is curved.

It has been proposed to use an ultraviolet-curable resin as the sealant 3h. However, the ultraviolet-curable resin has a problem in the adhesive strength of the seal portion, and the influence of ultraviolet rays on the alignment film cannot be ignored. Therefore, although a thermosetting resin is usually used as the sealant 3h, the curvature of the silicon substrate 1 as described above cannot be avoided.

Next, the cause of the occurrence of bending will be described with reference to FIG.
The thermal expansion coefficient of the silicon substrate 1 is 28 × 10 ⁻⁷ / ° C., and the thermal expansion coefficient of the glass substrate 2 is about 32 to 140 × 10 ⁻⁷ / ° C., and the thermal expansion coefficient of the glass substrate 2 is usually much larger. Therefore, as shown in FIG. 5 (1), the silicon substrate 1 and the glass substrate 2 having the same size L1 between the sealing agents 3h and 3h on both sides are bonded together with the thermosetting resin 3h, 135 ° C as
When the silicon substrate 1 is thermally cured by applying a certain amount of heat, the silicon substrate 1 extends to the dimension of L2 due to thermal expansion, whereas the silicon substrate 1 having a high thermal expansion coefficient extends to L3 due to the large thermal expansion. That is, L2 <L3.

As described above, the thermosetting resin 3h is thermoset with the glass substrate 2 side extending beyond the silicon substrate 1, so that when the temperature is returned to normal temperature, the heat shrinkage of the glass substrate 2 becomes as shown in (3). Is large, and the silicon substrate 1 is convexly curved. That is, when the temperature returns to the normal temperature, the silicon substrate 1 returns to the original dimension L1, but the glass substrate 2 side is thermoset and fixed while extending from the silicon substrate 1 side as shown in FIG. 3h
The dimension L2 between 3h and 3h becomes L4 after returning to room temperature, and is smaller than the dimension L1 on the silicon substrate 1 side. As a result, the silicon substrate 1 side is pulled by the heat shrinkage of the glass substrate 2 and is bent.

When such a curvature occurs, the cell thickness differs between the central portion and the outside of the liquid crystal panel. As a result, the contrast, the threshold voltage and the like become uneven, and the display quality deteriorates. Further, since a stress always acts on the seal portion 3h after the thermosetting, a stress also occurs on the silicon substrate 1 and the glass substrate 2, and there is a possibility that the seal portion 3h may be easily damaged when an external force acts.

On the other hand, as shown in FIG. 7A, in the liquid crystal panel in a completed state, even if the dimensions of the silicon substrate 1 and the glass substrate 2 are the same at room temperature, the size of the projection type liquid crystal display is large. Since a large amount of light is required, the amount of thermal expansion of the high-temperature side substrate (2) heated by the light source 8 is large, and the amount of thermal expansion of the opposite side substrate (1) is small. As a result, the substrate on the light source 8 side is curved, the cell thickness becomes non-uniform, and stress is generated in the sealant 3h. This figure is a reflection type projection type liquid crystal display. An image of the liquid crystal display is reflected on a screen S, and an enlarged image is displayed on the screen S.

[0012] The technical problem of the present invention focuses on such problems, a different silicon substrate and a glass base plate having thermal expansion coefficients bonded <br/> in manufacturing a liquid crystal panel, the substrate is curved The purpose of the present invention is to prevent the occurrence of stress in the sealing portion.

[0013]

Means for Solving the Problems The first aspect of the present invention is shown in FIG.
The silicon substrate 1 and the glass substrate 2 having different coefficients of thermal expansion are made of a material 3g having a rubber-like elasticity in a solidified state.
To form a liquid crystal enclosure space at room temperature
It is characterized by:

[0014]

As described above, according to the first aspect of the invention, the thermal expansion coefficients are mutually different.
Bonding different silicon substrate 1 and glass substrate 2
Te in forming a liquid crystal filling the space, bonded under room temperature using a material 3g having rubber-like elasticity in the solid phased state.
Therefore, substrates with different coefficients of thermal expansion are bonded together.
Does not require heating, so it is curved by heat change between both substrates
Does not occur. Also , as shown in FIG. 1, when used as a liquid crystal display panel , one of the substrates has a higher temperature than the other.
Even if exposed, it is not constrained by 3 g of elastic sealant and is flat.
The substrate on the high temperature side does not bend because
And 3g of sealant can be easily elastically deformed.
No stress occurs.

[0015]

EXAMPLES Next manufacturing method of a liquid crystal panel according to the present invention will be described how the embodied practically in the Examples.

FIG . 2 is a sectional view showing an embodiment of the first aspect of the present invention, in which a thermosetting resin 3h is not used, and a solidified state is sealed with a rubber-like elastic material. As such a material, a silicone-based adhesive rubber agent is suitable.

FIG. 2A shows a method of manufacturing a liquid crystal panel. First, an adhesive rubber 3g is applied between a glass substrate 2 and a silicon substrate 1, and the glass substrate 2 and the silicon substrate 1 are bonded together with a spacer 4 interposed therebetween. When left at room temperature for a predetermined time, the adhesive rubber agent solidifies, and the glass substrate 2 and the silicon substrate 1 are bonded to each other.

FIG. 3 is a perspective view showing a method of bonding liquid crystal panels using an adhesive rubber in the order of steps. (1)
As shown in FIG.
Using 25 etc., except for the liquid crystal injection port 6, adhesive rubber
After the application of 3 g, as shown in (2), the glass substrate 2 is overlaid with the glass substrate 2 on which silica balls are dispersed.

Next, as shown in (3), the interior is evacuated by placing it in a plastic bag 6 and evacuated to apply a uniform pressure between the substrates 1 and 2 to uniformly disperse 3 g of the adhesive rubber agent. And stretch it to the right thickness. In this state, after leaving at room temperature for about 24 hours, for example, it is taken out from the bag 7 for vacuum packing, liquid crystal is injected from the liquid crystal injection port 6, and the liquid crystal injection port 6 is adhered as shown in (4). When sealed with a rubber agent, the liquid crystal panel is completed.

As described above, the glass substrate 2 and the silicon substrate 1 are bonded with 3 g of an adhesive rubber agent having a rubber-like elasticity in a solidified state.
Since the liquid crystal panel to which is bonded does not require heating unlike the case of thermosetting resin, even when substrates having different coefficients of thermal expansion such as the glass substrate 2 and the silicon substrate 1 are bonded together, Does not expand or contract due to heat of

In the case of a projection type liquid crystal display, a large amount of light is required, and as shown in FIG.
Due to the heat of the light source 8, the substrate 1 on the light source 8 side
Larger thermal expansion.

Therefore, the substrate 1 on the side of the light source 8 expands more, but unlike the conventional liquid crystal panel, 3 g of the adhesive rubber agent is used.
Therefore, only the adhesive rubber 3g is elastically deformed, and the substrate 1 on the light source 8 side extends while being parallel to the other substrate 2. Therefore, the substrate 1 on the side of the light source 8 does not bend, and since the adhesive rubber 3g is rich in reversible elasticity, no stress is generated, and stress may be applied to both substrates. Absent.

FIG. 4 shows a cell thickness of a liquid crystal panel sealed by using an RTV manufactured by Toshiba Silicon Co., Ltd. as a sealant by the method of the embodiment of FIG. 3 and a liquid crystal panel bonded with a thermosetting resin due to a temperature change. It is the result of measuring the change. As the temperature of the liquid crystal panel gradually increases as indicated by the horizontal axis, the cell thickness at one point in the center of the liquid crystal panel gradually increases.

As shown by two curves, a solid line and a broken line,
As a result of the measurement of the sample at the point, the cell thickness of the liquid crystal panel sealed with the thermosetting resin increased rapidly with the temperature rise. At 200 ° C, the cell thickness increased by 5 μm. The liquid crystal panel sealed with the rubber agent does not become 1 μm thick even at 200 ° C.

The above description has been made on the assumption that the coefficient of thermal expansion of the glass substrate 2 is higher than that of the silicon substrate 1. However, when the silicon substrate 1 is larger than the glass substrate 2, 1 in FIG. It is sufficient if 2 is a silicon substrate. In addition, the conditions such as the size of each part and the thermosetting temperature in each embodiment can be obtained by calculation from the coefficient of thermal expansion determined by the materials of the silicon substrate 1 and the glass substrate 2.

[0026]

As described above, according to the first aspect of the present invention, the silicon substrate 1 and the glass substrate 2 are made of a material having a rubber-like elasticity in a solidified state without using a thermosetting resin at room temperature.
Since liquid crystal enclosing spaces are formed by bonding together, even if substrates having different coefficients of thermal expansion are bonded to each other, no heating is required, so that no bending occurs between the two substrates due to a thermal change.

Also, even if one substrate is exposed to a higher temperature than the other during use, it is not restrained by the elastic sealing agent 3g and expands and contracts in a planar state. Since the agent 3g is easily elastically deformed, no stress is generated on the substrate side.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a basic principle of a method for manufacturing a liquid crystal panel according to the present invention.

FIG. 2 is a longitudinal sectional view showing an embodiment of the present invention .

FIG. 3 is a perspective view showing a liquid crystal panel sealing method according to the present invention .

FIG. 4 is a characteristic measurement diagram showing the effect of the liquid crystal panel sealed by the method of FIG. 3;

FIG. 5 is a longitudinal sectional view showing a conventional liquid crystal panel thermosetting method.

FIG. 6 is a perspective view showing a conventional sealing method using a thermosetting resin.

FIG. 7 is a longitudinal sectional view showing a conventional projection type liquid crystal display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Glass substrate 3h Thermosetting sealing agent (thermosetting resin) 3g Sealing agent which has elasticity in solidified state 4 Liquid crystal sealing space 5 Spacer 6 Liquid crystal injection port 7 Vacuum packing bag 8 Light source S screen 25 Dispenser

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1339 505

Claims (1)

(57) [Claims] 1. A liquid crystal panel having liquid crystal encapsulated therein.
In the manufacturing method, the silicon substrate and a glass substrate having a different thermal expansion coefficients from each other
The atmospheric of a material having rubber-like elasticity in solidified state
Includes the process of forming the liquid crystal enclosure space by bonding under temperature
Method of manufacturing a liquid crystal panel, wherein the free it.