JPH06260410A - Ultraviolet applicating device and application of ultraviolet ray - Google Patents

Abstract

PURPOSE:To reconcile the inhibition of heat damage and the securement of the reliability of an ultraviolet applicating device by a method wherein the device is provided with an ultraviolet lamp of a water-cooled double tube structure for emitting ultraviolet rays on an object, a heat ray shielding filter, which is interposed between the object and the lamp, and a cooler for feeding cold air to the lamp and the object. CONSTITUTION:An object 2 consists of a laminated panel and ultraviolet application is conducted for fixing and bonding together one pair of substrates via an ultraviolet cured resin. An ultraviolet lamp 1 is involved in a jacket 3 made of quartz glass and a heat dissipation from the lamp is absorbed in the jacket 3 by circulating cooling water in the jacket 3. A heat ray shielding filter 4 is interposed between the lamp 1 and the object 2. The filter 4 reflects long- wavelength components, such as infrared rays, being contained in a radiation from the lamp 1 and selectively applies ultraviolet rays only to the object 2. Moreover, an external cooler 5 is incorporated in an ultraviolet emitting device, cold air is fed to the lamp 1 and the object 2 by the cooler 5 via a duct 6 and a force-cooling is conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet irradiation device and an ultraviolet irradiation method. More specifically, it relates to a high-output low-temperature exposure technique applied to assembly processing of liquid crystal panels and the like.

[0002]

2. Description of the Related Art Conventionally, a processing method for irradiating an article with ultraviolet rays has been widely used for the purpose of baking, drying, and surface treatment. BACKGROUND ART As a device for irradiating an article with ultraviolet rays, an ultraviolet irradiation device using an ultraviolet lamp is widely used. Among these, an ultraviolet irradiation device provided with a cooling mechanism for suppressing a temperature rise of an ultraviolet lamp or an article is known, and is disclosed in, for example, Japanese Utility Model Publication No. 3-56045 and Japanese Patent Publication No. 4-56289. There is.

[0003]

In recent years, as an application of an ultraviolet irradiation device, a technique has been developed in which a pair of substrates are bonded and fixed via an ultraviolet curable resin and processed into a laminated panel,
For example, it is applied to the assembly processing of liquid crystal panels. In a liquid crystal panel, a liquid crystal layer is enclosed between a pair of substrates, and it is important to completely bond and fix it in order to guarantee reliability, and high-power ultraviolet rays are irradiated. However, for example, 60 mW / cm ²
When the exposure process was performed with a moderate output, it was difficult to control the irradiated surface to room temperature with the conventional ultraviolet irradiation device. For example, if the exposure process is performed for 20 seconds at an output of 60 mW / cm ^2, the substrate surface will be heated to 80 to 90 ° C. As a result, there is a problem that thermal distortion occurs due to a difference in the coefficient of thermal expansion of the pair of substrates and a predetermined joining position accuracy cannot be secured. In addition, there is a problem that a fine film is laminated on the surface of the substrate, which causes thermal damage. On the other hand, if the substrate is simply cooled in order to prevent displacement and heat damage, there is a problem that the reaction progress of the ultraviolet curable resin is obstructed as the temperature becomes lower, resulting in a decrease in adhesive strength. Conventionally, it has been extremely difficult to achieve both thermal damage elimination and joint reliability.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, it is an object of the present invention to achieve both high power low temperature exposure and suppression of thermal damage and securing reliability. The following measures have been taken in order to achieve this object.
That is, the ultraviolet irradiation device according to the present invention is a water-cooled double tube structure ultraviolet lamp for irradiating an ultraviolet ray to an object, a heat ray blocking filter interposed between the object and the ultraviolet lamp, and an ultraviolet lamp and an object to cool air. And a cooler for supplying high temperature and low temperature exposure. Preferably, the ultraviolet irradiation device includes a power supply controller, and automatically switches the two-stage output of the ultraviolet lamp according to a predetermined sequence program. Further, an ultraviolet ray blocking mask is provided so that the non-exposed region of the object is selectively shielded.

The method of irradiating ultraviolet rays according to the present invention comprises a step of laminating a pair of substrates, at least one of which is transparent to ultraviolet rays, through an ultraviolet curable resin, and a step of irradiating ultraviolet rays at room temperature with a relatively low output. It includes a step of temporarily fixing the substrates to each other and a step of irradiating ultraviolet rays at a relatively high output to bond and fix the pair of substrates to each other to form a panel. For example, one substrate on which the pixel array is formed and the other substrate on which the counter electrode is formed can be bonded and fixed to each other to be processed into a display panel. In this case, at least the region in which the pixel array is formed may be selectively shielded from light and irradiated with ultraviolet rays.

[0006]

The ultraviolet irradiation apparatus according to the present invention has an efficient cooling structure for performing high power low temperature exposure. The UV lamp has a water-cooled double tube structure to remove heat radiation. A heat ray cut-off filter is incorporated so that only ultraviolet rays are selectively irradiated. It is equipped with a cooler and supplies cool air to the surface of the object to suppress temperature rise. With such a structure, when the exposure process is performed with an output of 60 mW / cm ² , for example, the surface temperature of the object can be controlled within the range of 24 ± 2 ° C., and irradiation at room temperature becomes possible.

The ultraviolet irradiation apparatus according to the present invention further includes a power supply controller, and automatically switches the two-stage output of the ultraviolet lamp according to a predetermined sequence program. This apparatus is suitable for joining and fixing a laminated panel, for example. First, ultraviolet rays are irradiated at room temperature with a relatively low output to temporarily fix the laminated substrates to each other. At this time, since the substrate is kept at room temperature, the positional deviation due to the difference in the coefficient of thermal expansion does not occur, the precise alignment becomes possible, and there is no fear of thermal damage. Next, the output is switched and ultraviolet rays are irradiated at a relatively high output to bond and fix the pair of substrates to each other to form a panel. As a result, the reaction of the ultraviolet curable resin used as the adhesive sufficiently progresses, and desired reliability can be secured. At this time, since temporary fixing has already been performed, there is no possibility of positional displacement even if the substrate temperature slightly rises. Since the ultraviolet irradiation device according to the present invention has an efficient cooling structure, it is possible to suppress the substrate temperature rise even if the ultraviolet light output is increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic block diagram showing the overall configuration of an ultraviolet irradiation device according to the present invention. The ultraviolet irradiation device includes an ultraviolet lamp 1 having a water-cooled double tube structure, and irradiates an object 2 with ultraviolet light. In this example, the object 2 is a laminated panel and is irradiated with ultraviolet rays in order to fix and bond a pair of substrates via an ultraviolet curable resin.
The ultraviolet lamp 1 is enclosed in a quartz glass jacket 3 and absorbs heat radiation from the lamp by circulating cooling water. A heat ray blocking filter 4 is interposed between the ultraviolet lamp 1 and the object 2, and, for example, a dichroic filter having a multilayer film formed on a quartz substrate can be used. The heat ray cut-off filter 4 reflects long-wavelength components such as infrared rays included in the radiation from the ultraviolet lamp 1, and selectively irradiates only the ultraviolet rays on the object 2. As a result, the object 2
It is possible to suppress the surface temperature rise of the. Furthermore, an external cooler 5 is incorporated, and cold air is supplied to the ultraviolet lamp 1 and the object 2 via the duct 6 to perform forced cooling. Cooler 5
Is composed of, for example, a cooler or the like and blows cold air of about 5 ° C. to enable room temperature cooling. A power supply controller 7 is connected to the ultraviolet lamp 1, and two-stage output switching is automatically performed by a predetermined sequence program. In addition, an ultraviolet blocking mask 8 for selectively blocking the non-exposed region of the object 2 is provided. The ultraviolet blocking mask 8 is attached to the robot arm 9 and is delivered to the surface of the object 2 as needed.

Next, the ultraviolet irradiation method according to the present invention will be described with reference to FIG. This irradiation method is applied to, for example, a process of joining and fixing a pair of substrates 10 and 11 to each other. First, as a preliminary step, a pair of substrates 10 and 11 at least one of which is transparent to ultraviolet rays are superposed on each other with an ultraviolet curable resin interposed therebetween. Next, the superposed state is supplied to the ultraviolet irradiation device by using a built-in carrier (not shown). Next, according to the automatic control of the power supply controller 7, a relatively low-power ultraviolet ray is irradiated at room temperature, and the pair of substrates 1
Temporarily fix 0 and 11 to each other. At this time, cool air is supplied from the cooler 5 to forcibly cool the surface of the object 2. In this example, the ultraviolet irradiation time can be set between 1 second and 999 seconds. For example, the UV curable resin is semi-cured and temporarily fixed by exposure for several tens of seconds at an output of 60 mW / cm ² . At this time, the surface temperature of the object 2 is 24 ± 2
It can be controlled within the range of ° C. Since no heat stress is applied, extremely accurate temporary fixing can be performed. After the lapse of a predetermined time, the ultraviolet lamp 1 is switched to a relatively high output side by automatic control by the power supply controller 7, and the ultraviolet light is irradiated for a predetermined time. As a result, the reaction of the ultraviolet curable resin proceeds, and the pair of substrates 10 and 11 are firmly bonded to each other. For example, the lamp output is 60mW / cm ² to 130mW /
Switch to cm ² and perform exposure processing for a predetermined time. Also in this case, the cool air is supplied from the cooler 5, and the ultraviolet lamp 1
With the water cooling and the heat ray cutoff of the heat ray cutoff filter 4, the surface temperature rise of the object 2 is suppressed as much as possible. In this example, the substrate temperature is 40 ± even when irradiated with ultraviolet rays at a relatively high output.
It can be controlled in the range of 10 ° C and there is no fear of causing heat damage.
In this way, the reaction of the ultraviolet curable resin is sufficiently promoted, the adhesive strength is increased, and the desired reliability is secured. This ultraviolet irradiation method can be applied, for example, when one substrate on which the pixel array is formed and the other substrate on which the counter electrode is formed are bonded and fixed to each other to be processed into a display panel. One substrate is made of, for example, quartz, and the other substrate is made of glass or the like. In this case, the thermal expansion coefficients of the two substrates are different by about one digit, and when the substrate temperature rises during the exposure process, thermal distortion occurs and alignment accuracy is impaired. In the present invention, since an ultraviolet irradiation device capable of high-power low-temperature exposure is used, it is possible to achieve both prevention of heat damage and securing of adhesive strength. Particularly, by performing a two-step exposure in which the lamp output is switched, extremely precise joining accuracy can be secured.

FIG. 2 is a schematic sectional view showing the housing structure of the ultraviolet irradiation device shown in FIG. The housing 12 is divided into two parts, a lamp chamber 13 and an irradiation furnace 14. The above-mentioned water-cooled double-tube UV lamp 1 is housed in the upper lamp chamber 13, and the target 2 is put into the irradiation furnace 14 below. Further, the above-mentioned heat ray blocking filter 4 is attached to the boundary between the lamp chamber 13 and the irradiation furnace 14. An exhaust duct port 15 is provided on the ceiling of the lamp chamber 13, and cold air inlets 16 and 17 are provided on the left and right side walls. Similarly, in the lower part of the irradiation furnace 14, the exhaust duct port 1
8 is provided, and cold air inlets 19 and 20 are provided on the left and right side walls. As shown, the lamp chamber 13 and the irradiation furnace 14
Are independent of each other, and an exhaust duct inlet and a cold air inlet are also provided separately. As a result, the lamp chamber 13 and the irradiation furnace 14 can be cooled under optimum conditions. If the lamp chamber and the irradiation furnace were designed to have the same temperature, the ultraviolet lamp temperature would be too low and the ultraviolet irradiation amount would not be stable. In the irradiation furnace 14, cold air inlets 19 and 20 are provided on the left and right sides so that the surface temperature distribution of the object 2 is not biased.

FIG. 3 is a schematic sectional view showing an example of a liquid crystal panel assembled by the ultraviolet irradiation method according to the present invention. The liquid crystal panel is one substrate 1 made of quartz or the like.
01 and the other substrate 102 made of glass or the like are bonded and fixed to each other with a predetermined gap therebetween. In addition,
After joining the substrates 101 and 102, a liquid crystal layer 103 is sealed and filled in the gap. The pair of substrates 101 and 102 are adhered to each other via an ultraviolet curable resin 104. A pixel electrode 105, a thin film transistor 106, a peripheral circuit 107, a terminal electrode 108 for external connection, and the like are integrally formed on the surface of the lower substrate 101, which is called a TFT substrate. Although not shown, the inner surface of the TFT substrate 101 is subjected to liquid crystal alignment treatment. On the other hand, the upper substrate 102
The color filter 109 and the counter electrode 110 are provided on the inner surface of the
Are formed. The color filter 109 is divided into segment patterns of RGB three primary colors.
5 is arranged so as to match the matrix pattern of 5. The substrate 102 having such a configuration is called a CF substrate. The inner surface of this CF substrate is also subjected to an alignment treatment for the liquid crystal layer.

The TFT substrate 101 is made of quartz and the CF substrate 102 is made of glass. There is an order of magnitude difference in the coefficient of thermal expansion between the two substrates. In view of this point, in the present invention, the ultraviolet curable resin 104 is cured by exposure at room temperature so that thermal strain does not occur. As a result, the TFT substrate 1
The 01-side matrix pixel electrode pattern and the CF substrate 102-side color filter pattern can be joined together while maintaining accurate alignment with each other. Further, reliability is secured by performing a two-step exposure to complete the reaction of the ultraviolet curable resin 104 and perform strong adhesion.

The liquid crystal panel shown in FIG. 3 is usually manufactured by a multi-cavity method using a large-sized quartz wafer.
FIG. 4 shows this multi-cavity method. Large format quartz wafer 1
11 are vertically and horizontally partitioned, and a chip of the liquid crystal panel 100 is obtained for each partition. After bonding the quartz wafer 111 and the glass wafer (not shown) to each other, the separation line 11
Divide along 2 to obtain individual liquid crystal panel 100. As shown in the figure, the liquid crystal panel 100 is assembled using an ultraviolet curable resin 104 printed in a frame shape, and a display area 113 is formed in the frame. It is preferable that the display area 113 is not irradiated with ultraviolet rays. If ultraviolet rays are irradiated, the liquid crystal alignment treatment and the fine structure of the thin film transistor may be damaged and display quality may be impaired.

Therefore, in the present invention, an ultraviolet blocking mask is used when performing the exposure process. Figure 5 shows the pattern shape.
Shown in. The ultraviolet blocking mask 114 is formed by using a quartz plate 115 having substantially the same size as the quartz wafer 111, and the surface of the quartz plate 115 is made of metal chrome or the like to shield the light.
16 are formed. When the ultraviolet blocking mask 114 is overlaid on the quartz wafer 111, the light blocking patterns 116 are aligned with the individual display areas 113. Therefore, the display area 11
It becomes possible to subject only the ultraviolet curable resin 104 to an exposure process in a state where 3 is selectively set as a non-exposed region. Quartz plate 11
5 is transparent to ultraviolet rays and can suppress irradiation loss.

Finally, a method of manufacturing the liquid crystal panel shown in FIG. 3 will be described with reference to FIG. First, in step S1, a TFT substrate and a CF substrate are created. At this stage, the substrates are not separated but are treated as wafers. Next, step S2
Surface treatment is performed if necessary. This treatment is performed to increase the adhesive strength of the ultraviolet curable resin. For example, depending on the composition of the liquid crystal alignment film, some liquid crystal alignment films have poor compatibility with the ultraviolet curable resin, so the liquid crystal alignment film is removed from the peripheral portion of the substrate surface. Alternatively, a base treatment for applying a surfactant may be performed along the peripheral portion of the substrate surface. Next step S
3, a sealant made of an ultraviolet curable resin (UV resin) is applied by printing along at least one peripheral surface of the substrate. This printing is performed by screen-printing a liquid sealant, for example. An acrylic or epoxy material is generally used as the UV resin. Epoxy type has better adhesiveness than acrylic type. Next step S
In 4, the pair of substrates are overlapped and pressed by a press or the like, sandwiching the UV resin printed and applied. At this time, spacers having a constant particle size may be scattered on the substrate surface to keep the substrate gap constant. In step S5, an ultraviolet blocking mask is set, and the non-exposed area of the liquid crystal panel is selectively shielded in advance. Next, in step S6, low-power ultraviolet irradiation is performed. At this stage, the curing reaction of the UV resin is stopped to some extent, but temporary tacking is possible as a whole and pattern shift can be suppressed. Subsequently, in step S7, high-power ultraviolet irradiation is performed. As a result, the curing reaction of the UV resin can be completed and strong adhesion can be achieved. Since temporary fixing has already been performed, there is no pattern deviation even if the substrate temperature rises to some extent, and precise alignment can be maintained. Next, in step S8, post-heat treatment is performed if necessary. The subsequent heat treatment is intended to further increase the adhesive strength, and is particularly effective when an epoxy UV resin is used. The temperature of the post heat treatment is set to, for example, about 50 ° C. within a range that does not cause heat damage to the substrate. In step S9, the substrates bonded to each other are divided into individual cells. Finally,
In step S10, liquid crystal is filled in the spaces between the individual cells to obtain a liquid crystal panel. In this way, generally, a multi-cavity method is adopted in order to efficiently manufacture the panel. In this case, instead of the above example, the cell division may be performed after enclosing the liquid crystal. In some cases, a single-piece picking method may be adopted from the beginning. Also in this case, the ultraviolet irradiation method according to the present invention is effective.

[0016]

As described above, according to the present invention, high-power low-temperature exposure is possible by providing an efficient cooling structure. The present invention enables highly precise bonding of a pair of substrates having different thermal expansion coefficients. Especially, the TFT substrate and C
This is effective when assembling a liquid crystal panel by stacking F substrates. Since the temperature rise of the substrate can be suppressed, the substrate does not warp due to heat and thermal damage can be prevented. Further, the two-step exposure can complete the curing of the UV resin to increase the adhesive strength and improve the reliability. There is an effect that the tact time can be shortened by automatically controlling the sequence program when performing the two-step exposure.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a configuration of an ultraviolet irradiation device according to the present invention.

FIG. 2 is a schematic sectional view showing a housing structure of an ultraviolet irradiation device according to the present invention.

FIG. 3 is a schematic cross-sectional view showing an example of a liquid crystal panel assembled by the ultraviolet irradiation method according to the present invention.

FIG. 4 is a plan view showing an assembly method of a liquid crystal panel.

FIG. 5 is a plan view showing a pattern shape of an ultraviolet blocking mask.

FIG. 6 is a manufacturing process diagram of the liquid crystal panel shown in FIG.

[Explanation of symbols]

 1 UV lamp 2 Target 3 Jacket 4 Heat ray blocking filter 5 Cooler 6 Duct 7 Power controller 8 UV blocking mask

Claims (6)

[Claims] 1. An ultraviolet lamp having a water-cooled double-tube structure for irradiating an object with ultraviolet rays, a heat ray blocking filter interposed between the object and the ultraviolet lamp, and a cooler for supplying cold air to the ultraviolet lamp and the object. Equipped with a UV irradiation device that enables high-output low-temperature exposure. 2. The ultraviolet irradiating device according to claim 1, further comprising a power supply controller for automatically switching the two-stage output of the ultraviolet lamp according to a predetermined sequence program. 3. The ultraviolet irradiation device according to claim 1, further comprising an ultraviolet shielding mask that selectively shields a non-exposed region of the object. 4. A step of laminating a pair of substrates, at least one of which is transparent to ultraviolet rays, via an ultraviolet curable resin, and a step of temporarily irradiating the pair of substrates to each other by irradiating ultraviolet rays at room temperature with a relatively low output. And a step of irradiating ultraviolet rays with a relatively high output to bond and fix a pair of substrates to each other to process into a panel. 5. The ultraviolet irradiation method according to claim 4, wherein one substrate on which the pixel array is formed and the other substrate on which the counter electrode is formed are bonded and fixed to each other and processed into a display panel. 6. The ultraviolet irradiation method according to claim 5, wherein ultraviolet irradiation is performed in a state where at least a region where the pixel array is formed is shielded selectively.