JP2002365652A - Method and apparatus for manufacturing liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that hardening of a UV (ultraviolet) curing sealing material is very difficult due to narrowing of a frame in the periphery of a liquid crystal panel. SOLUTION: The UV curing sealing material 8 is formed on a substrate with a desired shape. A liquid crystal is supplied in the inside of the formed UV curing sealing material 8 by dropping. The substrate and a counter substrate are stuck to each other. Both substrates are pressed so as to produce a specified gap. The first UV irradiation is carried out by maintaining temperature of both substrates <=50 deg.C while shielding light on a picture display area. Subsequently the sealing material 8 is hardened by UV irradiation at specified illuminance or over for a specified time or until reaching a specified integral of exposure while heating both substrates up to 70-100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a liquid crystal panel of a liquid crystal display used as a display of many electronic devices.

[0002]

2. Description of the Related Art As a method of manufacturing a liquid crystal panel, the following method called a liquid crystal dropping method is known. An alignment film made of a polyimide resin is formed on a substrate on which a pair of electrodes are formed, and the alignment direction of the liquid crystal is determined by rubbing the surface of the alignment film with a cloth called rubbing. A UV-curable sealant is formed in a predetermined pattern on one of the substrates subjected to the alignment treatment by screen printing or drawing application using a dispenser. Then, a required amount of the liquid crystal material is dropped and supplied into a region surrounded by the UV-curable sealant. A spacer material for forming a gap between the substrates is arranged on the other substrate. These two substrates are 100P
a. Positioning is performed under reduced pressure of a or less, and bonding is performed.

Next, pressure is applied until a predetermined gap is formed between the substrates. After that, shade the area other than the seal part,
The seal is cured by irradiating only the seal portion with UV light. Then, a liquid crystal panel portion is cut out from the two bonded substrates to form a liquid crystal cell. When a thermosetting sealant is used instead of a UV-curable sealant, in the thermosetting process performed after the substrates are bonded, thermal deformation of both substrates due to heating and curing shrinkage of the seal due to heat shrinkage of the seals. However, there are problems such as a decrease in alignment accuracy, breakage of a seal line, and a gap failure due to a floating of the seal. Further, since about one hour is required for heat curing, the production efficiency is reduced, and the size of the thermosetting equipment is increased due to the increase in the size of the mother substrate.

[0004]

When a UV-curable sealant is used, it is necessary to irradiate the seal portion with UV light for curing the seal. Therefore, in the case of a substrate of a transparent electrode such as ITO or a substrate on which a color filter is formed, it is necessary that the panel has a seal formed on an outer peripheral portion of the black matrix. However, in recent years, as shown in FIG.
2, the number of cases where the electrodes 6 on the array substrate 5 are formed of Al also increases. And the UV light is blocked by the Al electrode. In such a liquid crystal panel, it is very difficult to cure the UV-curable sealant.

The first problem is that, among the above, the seal is disposed on the black matrix 4 and the portion of the seal 2 where the Al electrode 6 overlaps the UV-curable seal is most likely to cure the seal by UV irradiation. Becomes difficult. Generally, the black matrix 4 has no light transmitting portion, but the electrode width of the Al electrode portion 6 on one side is 50 to 1.
About 00 μm, the space between the electrodes is about 5 to 50 μm, and a part transmits light. Therefore, when UV light is irradiated from the Al electrode side 6, the space between the electrodes is exposed to UV light.
Sealing can be performed by light irradiation, but it is difficult to cure the seal at the seal portion under the electrode because UV light is shielded.

A second problem is that only the seal portion has a U
In the process of irradiating the V light to cure the seal, the UV light leaks into the region adjacent to the seal on the substrate at the time of UV irradiation, which leads to device damage to the liquid crystal material, the alignment film, and the drive transistor. The space between the seal position and the pixel area is close to about 0.5 to 1 mm due to the narrowing of the peripheral frame, and these damages lead to deterioration of display quality.

As a third problem, in the liquid crystal dropping method, an uncured seal and the liquid crystal 7 are in contact with each other in a step of bonding substrates. Here, U in the next process
If the temperature of the substrate becomes high during the curing of the seal by light irradiation in the V-seal curing step, the sealing composition elutes from the sealant into the liquid crystal during the curing of the seal, leading to deterioration of display characteristics such as an afterimage. Furthermore, thermal deformation accompanying the rise of the substrate temperature due to light irradiation at the time of curing the seal leads to a decrease in the positioning accuracy of the substrate.

A fourth problem is that, when the color filter substrate 3 and the array substrate 5 are attached to each other and the uncured UV-cured seal and the liquid crystal 7 are kept in contact for a certain period of time or longer, the seal is kept at room temperature. The seal component such as a photo-initiator elutes from the agent into the liquid crystal 7 and leads to deterioration of display characteristics such as an afterimage.

The present invention relates to a method of manufacturing a liquid crystal panel using a UV-curable seal capable of improving the accuracy of the bonding position of a substrate and the productivity.
It is an object of the present invention to provide a method and an apparatus for manufacturing a liquid crystal panel that can cope with the use of a light-shielding material.

[0010]

In order to achieve this object, the present invention provides a UV curable sealant formed in a desired shape on a substrate, and a liquid crystal is dropped inside the formed UV curable sealant. The first substrate is supplied with the substrate and the opposite substrate bonded together, pressurized so that the two substrates have a predetermined gap, and maintaining the temperature of the two substrates at 50 ° C. or lower while shielding the image display area from light. The part which is not shaded by UV irradiation is cured by sealing, and thereafter, the substrates are heated to 70 ° C.
The second UV irradiation is performed while heating to 100 ° C. to cure the seal.

As a result, the alignment accuracy between the two substrates is high, and the sealing agent can be sufficiently cured even when the electrodes are shielded from light, so that a liquid crystal panel manufacturing method with high display quality can be provided.

[0012]

DETAILED DESCRIPTION OF THE INVENTION FIG.
UV curing process will be described.

The array substrate 5 and the color filter substrate 3 are
It is bonded via a UV-curable sealant 8.
A UV light shielding mask 9 for protecting a display area such as a transistor of the array substrate 5 from UV damage is arranged in parallel with the array substrate 5 at an interval of several 100 μm to several mm. In this state, in the first step, the panel heater 10 heated to about 95 ° C.
The substrate is retreated to a position separated by not less than mm to suppress the heating of the substrate, and the UV parallel light 11 is irradiated at a predetermined illuminance or higher for a predetermined time or until a predetermined integrated exposure amount is reached at a substrate temperature of normal temperature to 50 ° C. or lower. By this UV irradiation, the seal portion of the space between the electrodes to which the UV light is directly irradiated is cured, and the elution of the seal component from the seal to the liquid crystal during the seal curing is reduced. With the positioning accuracy of both substrates not degraded due to substrate thermal deformation,
The space between the electrodes is cured by sealing to increase the bonding strength between the substrates.

Next, in a second step, a UV light shielding mask 9 is used.
The distance between the substrate and the array substrate 5 and between the color filter substrate 3 and the panel heater 10 are set close to several 100 μm,
While heating to about 100 ° C, the UV parallel light 11
At a predetermined illuminance or higher for a predetermined time or until a predetermined integrated exposure amount is reached. At this time, if the temperature of the sealant rises due to heating, the sealing component is likely to be eluted into the liquid crystal. Therefore, it is desirable to start UV irradiation simultaneously with heating to cure the seal. In the process of increasing the substrate temperature, the bonding strength between the substrates is ensured by the first step of seal hardening, so that the change in the alignment accuracy is small. Since the seal hardening reaction is promoted in the state where the sealant temperature is high, the seal hardening proceeds even in the seal portion under the electrode where the UV light is not directly irradiated. The substrate temperature is 100
If the temperature exceeds ℃, the temperature may be higher than the phase transition temperature of the liquid crystal, and the elution of the liquid crystal from the uncured portion of the seal under the electrode may easily progress. As described above, by controlling the substrate temperature and the UV irradiation, it is possible to cure the space between the electrodes, which is the shadow of the UV irradiation, and the seal portion under the electrode.

Here, the commercially available UV lamp light source used in the UV sealing step has an initial illuminance of at least ±
There is a variation of about 20%, and the illuminance of the UV lamp is reduced by about 30% during use, so that the UV illuminance is 50%.
% Fluctuates. UV commonly used in general exposure process
In the control based on the exposure amount, the UV exposure amount is determined by the product of the illuminance and the irradiation time. U
The main parameters of the curing reaction of the V-curable seal are the temperature of the sealant determined by the substrate temperature and the amount of UV exposure applied in that state. Therefore, when the substrate temperature rises with the lapse of time during UV irradiation, if the control is performed using the UV exposure amount, the substrate temperature during UV irradiation may vary depending on the UV illuminance, and the seal curing quality may vary. Therefore, in order to perform UV exposure in a state where the sealant temperature is in a predetermined temperature range,
Desirably, the UV exposure is controlled for a predetermined period of time with a predetermined illuminance or higher.

FIG. 2 shows an example of an apparatus for manufacturing a liquid crystal panel according to an embodiment of the present invention. The optical system for irradiating UV parallel light has a high-pressure mercury lamp 12, a reflection mirror 13 for cutting infrared light, a fly-eye lens unit 14, an optical shutter 15, and an emitted light angle reflected within 6 degrees from a vertical axis. And a reflecting mirror 16 whose shape is designed as follows.
Also, on the panel heater 10 heated to about 95 ° C.,
A support mechanism 17 for the UV light shielding mask 9 and a support mechanism 18 for the array substrate 5 and the color filter substrate 3 are provided. Here, the color filter substrate 3 and the array substrate 5 can move the substrate in a horizontal plane from the side surface of the substrate by the fine movement mechanism 19. The illuminometer 20 and the exposure control unit 2
According to 1, a determination of a predetermined illuminance or more, an integrated exposure calculation is performed,
The exposure is controlled by opening and closing the optical shutter 15.

First, in order to suppress substrate heating from the panel heater 10 heated to about 95 ° C. to 50 ° C. or less, 1
The color filter substrate 3 is supported by the support mechanism 18 at intervals of at least 00 mm. Then, the array substrate 5 and the UV light shielding mask 9 bonded to the color filter substrate 3 are
It is supported by the mask support mechanism 17 so as to keep an interval of 00 μm.

Next, the alignment substrate 22 of the UV light-shielding mask and the substrate detects the positional shift between the UV light-shielding mask 9 and each alignment mark arranged on the array substrate 5 by using a CCD camera or the like, and moves the array substrate 5. Fine movement mechanism 1
At 9, the position is adjusted in the horizontal plane, and the alignment with the UV light shielding mask 9 is performed. Here, as the UV irradiation of the first step,
After the light emitted from the high-pressure mercury lamp 12 is reflected by the reflecting mirror 13 and the intensity distribution is made uniform by the fly-eye lens unit 14, the optical shutter 15 is opened to transmit UV light, and the UV mirror 23 is reflected by the reflecting mirror 16. Form.

Then, after the array substrate 5 and the color filter substrate 3 are irradiated with UV light through the UV light shielding mask 9 for a predetermined time or until a constant integrated exposure amount is reached, the light shutter 15 blocks the UV light.

Thereafter, the substrate is heated to 70 ° C. by the panel heater 10.
The color filter substrate 3 is supported by the support mechanism 18 in a state where the interval is approached to about several hundred μm to heat the color filter substrate 3 to about 100 ° C. The array substrate 5 and the UV light shielding mask 9 bonded to the color filter substrate 3 are supported by the mask support mechanism 17 close to the panel heater 10 so as to keep the same interval as in the first step. At this time, if the alignment between the UV light shielding mask 9 and the array substrate 5 is misaligned, the alignment may be performed again. Here, UV of the second step
As irradiation, the light emitted from the high-pressure mercury lamp 12 is reflected by the reflecting mirror 13, and the intensity distribution is made uniform by the fly-eye lens unit 14.
The light is transmitted, and the reflecting mirror 16 forms the UV parallel light 23.

When irradiating the array substrate 5 and the color filter substrate 3 with UV through the UV light shielding mask 9, the illuminometer 20 determines that the UV illuminance value is equal to or more than a predetermined value by the control controller 21. After UV irradiation until time or a constant integrated exposure amount, the optical shutter 15
To block UV light. Although the case of using the panel heater as the substrate heating means has been described, the heating means may be another heating means such as irradiating the substrate with an infrared lamp.

In the step of shielding the vicinity of the image display area where the portion where UV damage is a problem is arranged and irradiating the sealing portion with UV light to cure the seal, the substrate and the UV light shielding mask 9 are separated. Arranged in parallel and irradiated with UV parallel light having an angle of 6 degrees or less from the vertical axis, and the UV light is applied to the area of the liquid crystal material, alignment film, drive transistor existing in the area adjacent to the seal. Device damage is prevented by preventing leakage. Also, in order to cure the entire seal portion, the liquid crystal at the boundary with the seal is irradiated with UV light, but UV light of 310 nm or less damages the liquid crystal, so that the wavelength band is 310 nm or more. The band is irradiated with UV light to prevent damage to the liquid crystal.

FIG. 3 is a diagram for explaining a method of manufacturing a liquid crystal panel according to the embodiment of the present invention, which is an integrated process from bonding of substrates to curing of a UV seal. The substrate bonding device 24 to the UV seal curing device 25 are connected by a substrate transfer system 26, and the system controller 27 controls the transfer timing and the substrate processing status in each facility to perform integrated processing. Here, the bonding device 2
At 4, the apparatus waits for the UV seal curing device 25 to be ready to receive the substrate before the lamination of the array substrate and the color filter substrate immediately before the uncured sealant comes into contact with the liquid crystal. When the seal hardening completion signal 28 of the UV seal hardening device 25 reaches the system controller 27, the system controller 27 issues a processing restart signal 29 to the bonding device 24 to bond both substrates. Then, the bonded substrate 30 is transferred to the UV seal hardening device 25 without waiting time in the substrate transfer system 26 to start the seal hardening. As described above, the process from the bonding to the curing of the UV seal is performed in an integrated manner, and the time during which the uncured sealant and the liquid crystal are in contact is controlled within a predetermined time. The time varies depending on the combination of the liquid crystal material and the sealant in contact, but is preferably within a range of 5 to 15 minutes.

A bonding start signal is sent from the bonding device 24 and a UV irradiation start signal is sent from the UV seal curing device 25 to the system controller 27 until the UV curing starts after the uncured UV seal comes in contact with the liquid crystal. May be recorded in the system controller 27 as manufacturing information of each manufacturing panel.

[0025]

As described above, according to the present invention, it is possible to cope with the use of light-shielding materials such as narrower frames and Al electrodes, and it is possible to improve the bonding position accuracy of the substrates and the productivity.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the UV seal curing process.

FIG. 2 is a schematic diagram of an apparatus for manufacturing a liquid crystal panel according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a method for manufacturing a liquid crystal panel according to an embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a liquid crystal panel bonded together.

[Explanation of symbols]

 Reference Signs List 8 UV curing type seal 9 UV light shielding mask 10 Panel heater 12 High pressure mercury lamp 16 Reflector 17 UV light shielding mask support mechanism 18 Color filter substrate support mechanism 20 Illuminance meter 22 UV light shielding mask and substrate alignment system 24 Substrate bonding device 25 UV seal curing device 26 Substrate transfer system 27 System controller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuo Ueno, Inventor 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Satoshi Yamada 1006 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial F Terms (reference) 2H089 NA22 NA37 NA40 NA44 NA45 NA60 QA12

Claims (6)

[Claims] A step of forming a UV-curable sealant on a substrate in a desired shape; a step of supplying liquid crystal dropwise into the formed UV-curable sealant; and a step of opposing the substrate facing the substrate. A step of bonding, a step of applying pressure so that the two substrates have a predetermined gap, and a first step of maintaining the temperature of the two substrates at 50 ° C. or less while shielding the image display area.
UV-irradiation to cure the unshielded portion with a seal, and after this process, the two substrates are heated to 70 ° C to 1 ° C.
Performing a second UV irradiation while heating to 00 ° C. to cure the seal. 2. The UV irradiation on the seal portion has a wavelength band of 3
2. The method for manufacturing a liquid crystal panel according to claim 1, wherein the step is performed using UV parallel light in a wavelength band of 10 nm or more. 3. The method for manufacturing a liquid crystal panel according to claim 1, wherein the time during which the uncured sealant and the liquid crystal are in contact is maintained within a predetermined time. 4. An optical system for irradiating a substrate with parallel light in a UV wavelength band, a mask for shielding an image display area, mask alignment means for aligning and holding the mask, and a substrate stage for holding the substrate. And a substrate heating means for heating and holding the substrate at an arbitrary temperature, and a measuring means for monitoring UV illuminance and irradiation time. 5. The optical system according to claim 4, wherein the optical system for irradiating the substrate with parallel light in the UV wavelength band is equipped with an optical filter for removing a wavelength of 310 nm or less and a wavelength in an infrared region. LCD panel manufacturing equipment. 6. A mask is coated with an optical film which does not transmit a wavelength of 310 nm or less and a wavelength of an infrared region in a light transmitting region and transmits a wavelength of a visible light region of 310 nm or more. An apparatus for manufacturing a liquid crystal panel according to any one of claims 4 and 5.