JP3080164B2 - Electroluminescent element sealing 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 flat panel display using electroluminescence (hereinafter referred to as "EL") as a light emitting element.
That is, the present invention relates to a method for sealing the EL element in an EL display assembling process. Specifically, a liquid sealant is applied between the transparent substrate on which the rectangular electroluminescent element layer is formed and the cover plate, and one of the transparent substrate and the cover plate is adsorbed and held on a surface plate. On the other hand, the present invention relates to a method of sealing an electroluminescent element layer by vertically moving an adsorbing member, the other of which is adsorbed and held by an elevating means, so that the sealant is spread out.

[0002]

2. Description of the Related Art Conventionally, as a method of sealing an EL element of this kind, for example, as shown by a solid line in FIG. A rectangular transparent substrate 2 is sucked and held on the lower platen A, and a sealant 4 is provided at the center of the upper surface of the transparent substrate 2 as shown by a solid line in FIG. The EL element layer 1 is applied in a concentrated manner, and a resin frame 10 is formed around the EL element layer 1 to prevent the sealant 4 from protruding and secure a gap thickness. Then, as shown by a two-dot chain line in FIG. 8A, the suction member B and the cover plate 3 held by suction are slowly lowered in a horizontal state by the operation of the lifting / lowering means C, and the cover plate 3 is sealed with the sealant. 8, the sealant 4 at the center is crushed and spread radially as shown by the two-dot chain line in FIG. After the collision, the sealant 4 spreads over the entire surface due to a capillary phenomenon generated between the cover plate 3 and the transparent substrate 2 to seal the EL element layer 1.

[0003]

However, in such a conventional EL element sealing method, the sealing agent is radially pushed out from the central portion of the transparent substrate and spreads to the peripheral portion by a capillary phenomenon. It takes a long time for the sealant to reach the corners of the part and completes it. As a result, there is a problem that the tact time of the device becomes long. In order to solve this problem, it is necessary to increase the number of devices or to install a buffer or the like in order to wait until the spreading of the sealant is completed.
Furthermore, since the sealant is applied in a concentrated manner to the central portion of the transparent substrate, the radial distance from this central portion is shorter than the outer four corners, in the region of each side intermediate portion, the sealant is likely to protrude, To solve this, around the EL element layer,
It is necessary to provide a frame for preventing the sealant from protruding, and there is a problem that the cost of the product increases. In addition, the liquid sealant applied to the center of the transparent substrate has a substantially flat upper end unless the viscosity is extremely high. The surface contact makes it easy for air to enter at the moment of the surface contact, and the sealant is crushed at once at the moment of contact, but the cover plate is held by the suction member so as not to be able to move up and down. A rapid change in the shape of the sealant could not be followed, and air was easily mixed between these cover plates and the upper end of the sealant. As a result, air bubbles are generated in the sealant, and the air bubbles remain between the cover plate and the EL element, causing a problem that the EL element is deteriorated or the quality of the EL display panel is deteriorated. In order to prevent the generation of the air bubbles, it is conceivable that the descent speed at the moment when the cover plate contacts the upper end surface of the sealant is extremely low, but the height position at the time of this contact is determined by the transparent substrate or the cover plate. It is difficult to detect the position due to factors such as the thickness dimension of the sealant and the shape of the sealant after application, so it is necessary to reduce the speed of the entire lowering process of the suction member and the cover plate sucked and held by the suction member. There is a problem that the tact time becomes longer. Furthermore, E
The filling amount of the sealant necessary for sealing the L element layer needs to completely match the volume formed by the area surrounded by the frame and the height of the frame. Due to the large variation, when the frame is lower than the set height, the sealant protrudes. On the contrary, when the frame is high, the sealant is insufficient and bubbles are generated between the transparent substrate and the cover plate, and EL is generated.
There is a problem that the element is deteriorated and the quality of the EL display panel is deteriorated. In order to solve this, it is necessary to introduce an expensive device in order to improve the height accuracy of the frame, and there is a problem that the cost of the EL display panel cannot be reduced. Even if the height accuracy of the frame can be improved, it is difficult to detect the position where the cover plate comes into contact with the upper surface of the frame for the above-described reason. Therefore, there is a problem that the cover plate is lowered too much and the frame is damaged.

An object of the present invention in claim 1 is to spread the sealant over the entire area while preventing air from entering or protruding in a short time.

[0005]

In order to achieve the above-mentioned object, the present invention according to claim 1 of the present invention is directed to a transparent substrate or a cover plate which is attracted and held on a surface plate. A large amount of sealant is dispersed and applied to the outer peripheral portion at appropriate intervals, and a small amount of sealant is placed on the other of the cover plate or the transparent substrate that is sucked and held by the suction member at a position opposed to the large amount of sealant. Respectively, and a step of bringing the upper end of the large amount of sealant and the sealant hanging down in an inverted mountain shape into close contact with each other by an elevating / lowering means.

[0006]

According to the first aspect of the present invention, the substantially flat upper end portion of the large amount of the sealant and the small amount of the sealant hanging down in an inverted mountain shape are respectively formed at one point by bringing the transparent substrate and the cover plate closer by the operation of the lifting / lowering means. This is a method in which contact is started, spreads in a substantially uniform amount, and then all of these sealants merge to reach the periphery of the cover plate or the transparent substrate.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a rectangular cover plate 3 smaller than the rectangular transparent substrate 2 on which a rectangular electroluminescent element layer plate 1 is formed as shown in FIGS. The transparent substrate 2 is suction-held on the upper surface of the lower surface plate as the surface plate A, and the cover plate 3 is suction-held on the lower surface of the upper surface plate as the suction member B. This shows a case in which a gap G having a predetermined thickness is formed between the transparent substrate 2 and the cover plate 3 by moving the board B up and down by a lifting means C having a conventionally well-known structure.

The transparent substrate 2 is made of glass, and on one surface thereof, a rectangular EL element layer 1 is formed in a thin film between both anode and cathode electrode patterns (not shown). . Further, a large amount of the sealant 4 is dispersed at appropriate intervals on the central portion and the outer peripheral portion of the transparent substrate 2 after the suction and holding on the lower platen A or before the suction and holding on the lower platen A. Apply. Specifically, about 60 to 90% of the sealant 4 necessary for sealing the EL element layer 1 is applied to a central portion of the transparent substrate 2 by a dispenser (not shown), and Most of the remaining sealant 4 is divided into equal amounts and applied by a dispenser at appropriate intervals. In the state after the application, the large amount of sealant 4a is used.
Are approximately flat at the top.

The application position of the large amount of the sealant 4 changes according to the planar shape of the EL element layer 1 and the transparent substrate 2. For example, when the EL element layer 1 and the transparent substrate 2 are square as shown in FIG.
In the center where 2a intersects, apply a large amount of sealant 4a1
Four large-capacity sealants 4a2 smaller than the large-capacity sealant 4a1 are disposed at the four outer peripheral corners equidistant from the intersection on the diagonal lines 2a, 2a. In the case where the EL element layer 1 and the transparent substrate 2 are rectangles having a small aspect ratio as shown in FIG. 3A, two large mass sealings are made along a center line 2b parallel to the long side of the transparent substrate 2. Agents 4a3, 4a3
Are disposed at the center part equidistant from the center point 2c, and four large-capacity sealants 4a4 smaller than the large-capacity sealant 4a3 are disposed at the four outer peripheral corners equidistant from the intersection 2c on these diagonals 2d, 2d. ing. Further, when the EL element layer 1 and the transparent substrate 2 are rectangles having a large aspect ratio as shown in FIG. 4 (a), one large sealing agent 4a5 is arranged at the center point 2f of the transparent substrate 2 and Center line 2e parallel to the long side
The two large sealants 4a6 and 4a6, which are slightly smaller than the large sealant 4a5,
And four large-capacity sealants 4a7 smaller than the large-capacity sealant 4a6 are disposed at the four outer peripheral corners equidistant from the intersection 2f on these diagonal lines 2g, 2g.

The cover plate 3 is made of, for example, transparent glass, and has a large amount of the lower platen A at the center and the outer peripheral portion thereof before being sucked and held on the lower surface of the upper platen as the suction member B. A small amount of the sealant 4b is applied to the position opposed to the sealant 4a by a dispenser.
The amount of the small amount of sealant 4b to be applied is such that the coated surface does not fall even if the coated surface is directed downward so as to face the transparent substrate 2. When the coated surface is directed downward,
As shown in FIG. 1, each central portion hangs in an inverted mountain shape.

Further, the application position of the small amount of the sealant 4b is the same as the application position of the large amount of the sealant 4 as shown in FIG.
As shown in FIG. 4A, it changes according to the planar shape of the EL element layer 1 and the transparent substrate 2. That is, when the EL element layer 1 and the transparent substrate 2 are square as shown in FIG.
a1 and a small amount of sealant 4a2 arranged at four corners of the outer periphery.
Are disposed on the cover plate 3 so as to face each other. When the EL element layer 1 and the transparent substrate 2 are rectangles having a small aspect ratio as shown in FIG. 3A, a large amount of sealants 4a3 and 4a3 disposed at the center of the transparent substrate 2 and four outer peripheral corners are provided. The small sealants 4b3, 4b3, 4b4... Are arranged on the cover plate 3 so as to be opposed to the small large sealants 4a4. Further, an EL element layer 1 and a transparent substrate 2 as shown in FIG.
Is a rectangle having a large aspect ratio, a large amount of sealant 4a5 and a small amount of sealants 4a6 and 4a6 arranged at the center of the transparent substrate 2 and a small amount of sealant 4a7 arranged at four corners of the outer periphery. A small amount of sealant 4b5, 4b6, 4b6, 4b7,... Is arranged on the cover plate 3 so as to face each other.

The lower surface plate A is fixed on a base D so that the upper surface thereof is horizontal, and the upper surface thereof is flat and has a plurality of suction ports A1 such as a large number of holes and grooves for vacuum suction.

The upper stool B is configured to move up and down with respect to the lower stool A by a raising / lowering means C having a conventionally well-known structure, with its lower surface being held parallel to the upper surface of the lower stool A. In the case of this embodiment, the elevating means C is vertically reciprocable along a plurality of guides C1 erected on the base D and the guides C1 fixed to the upper stool B. A plurality of sliding portions C2 and a ball screw C4 connected to a driving source C3 such as a motor and screwed to the sliding portion C2, and the ball screw C4 is rotated by the operation of the driving source C3. The moving portion C2 and the upper stool B move up and down along the guide C1. The operation of the driving source C3 is controlled by a controller (not shown).
Is stopped at the upper limit position, and the first operation signal is input, thereby lowering the sliding portion C2 and stopping the lowering when the upper stool B is lowered to the set height position. , The sliding portion C2 is raised to return to the initial state.

The sealant 4 is a liquid adhesive made of an ultraviolet curable resin or a liquid adhesive made of a thermosetting resin, and the filling amount is between the transparent substrate 2 and the cover plate 3. It corresponds to the volume of the formed gap G, and more specifically, is obtained by multiplying the thickness dimension of the gap G by the area of the cover plate 3. Then, at an appropriate timing after the sealant 4 is sufficiently spread by the elevating means C,
In the case of an ultraviolet curable adhesive, the transparent substrate 2 and the cover plate 3 are solidified by irradiating ultraviolet rays, and in the case of a thermosetting adhesive, the transparent substrate 2 is solidified by heating. And the cover plate 3 are bonded.

Next, a method for sealing such an EL element will be described using the above-described apparatus. First, in the initial state, the upper stool B rises as shown by the solid line in FIG. 1, and in this state, the transparent substrate 2 is placed at the fixed position on the upper surface of the lower stool A and the After the suction is started, the transparent substrate 2 is sucked and held, and after this sucking and holding, the transparent substrate 2 to which the large amount of the sealant 4a is applied or the large amount of the sealant 4a is previously applied is sucked and held. Thereby, a large amount of sealant 4a ...
Has a substantially flat upper end.

At a fixed position on the lower surface of the upper stool B, a cover plate 3 coated with a small amount of a sealing agent 4b in advance is arranged to start suction from the suction port B1 for suction and holding. Alternatively, a small amount of the sealant 4b is applied after the cover plate 3 is sucked and held. Thereby, each small amount sealant 4
b ... each has a central portion that hangs in an inverted mountain shape, and is opposed to the substantially flat upper end of the large amount of sealant 4a.

In this state, when the drive source C3 of the lifting / lowering means C is activated and the lowering of the upper stool B is started, the small amount of sealant 4b hangs down in an inverted mountain shape as shown by a two-dot chain line in FIG. The central part starts to contact the mass sealant 4a... As a result, no air is mixed at the time of merging, and no air bubbles are generated in the sealant 4.

After the small amount of sealant 4b and the large amount of sealant 4a arranged at the central portion and the outer peripheral portion come into contact at one point, respectively, and converge, the lower amount of the upper surface plate B lowers, and the amount of the substantially uniform amount respectively. It spreads radially, and when it spreads to some extent, all the sealants 4 merge. At this time, as shown by the solid line in FIG.
Is completed, and as shown in FIGS. 2 (b) to 4 (b), the outer peripheral four corners 3a of the cover plate 3 and the middle parts 3b of each side are covered, and the outermost parts of the outer peripheral parts become the peripheral parts 3c. At this point, the area where the sealant 4 has not reached is very small. After that, the sealant 4 reaches the entire periphery 3c without protruding, and the EL element layer 1 is completely sealed.

Accordingly, since the spread of the sealant 4 starts to spread almost simultaneously at multiple points, the time required until the state shown in FIGS. 2 (b) to 4 (b) is extremely short. Furthermore, sealant 4
When the spread of the sealant is started, a large amount of the sealant 4a is already dispersed and distributed over substantially the entire area. Distortion occurs due to a difference in gap between the substrate 2 and the cover plate 3, and as a result, a fatal drawback that the display of the EL display panel is deteriorated as a product can be prevented.

Thereafter, the suction from the suction port B1 of the upper platen B is released to release the suction of the cover plate 3. Subsequently, the drive source C3 of the lifting / lowering means C is operated, and the upper platen is operated. B
5 and returns to the initial state as shown by the two-dot chain line in FIG. 5, thereafter, the suction from the suction port A1 of the lower platen A is released to release the suction of the transparent substrate 2, and the sealant 4 is removed. The filled transparent substrate 2 and cover plate 3 are sent to the next step. At this time, the sealant 4 filled between the transparent substrate 2 and the cover plate 3 on the lower platen A is irradiated with ultraviolet rays or heated to solidify part or all of the sealant 4. After the transparent substrate 2 and the cover plate 3 are bonded together, they are sent to the next step, or after they are sent to the next step, they are irradiated or heated with ultraviolet light to solidify the sealant 4 and The cover plate 3 is attached. Thereafter, the above operation is repeated.

6 and 7 show another embodiment of the present invention. In this embodiment, an upper platen is supported as the suction member B so as to be vertically movable with respect to a lifting / lowering means C. A stretchable elastic member 6 for elastically pressing the upper surface plate B and the cover plate 3 sucked and held thereon toward the transparent substrate 2 sucked and held on the upper surface of the lower surface plate as a surface plate A is arranged. The configuration provided is different from the embodiment shown in FIGS. 1 to 5, and the other configuration is the same as the embodiment shown in FIGS. 1 to 5.

In this embodiment, a holding plate 5a is fixed over a plurality of sliding portions C2 of the elevating means C, and a plurality of or a single ball bush 5b is fixed to the holding plate 5a.
A sliding mechanism comprising a spline shaft 5c and a spline shaft 5c is disposed so as to be able to reciprocate up and down, and at the lower end of the spline shaft 5c protruding downward from the ball bush 5b,
The upper surface plate B is continuously provided such that the suction port B1 faces the upper surface of the lower surface plate A in parallel. Further, for example, a coil spring is disposed as the elastic member 6 between the upper end of the spline shaft 5c projecting upward from the ball bush 5b and the upper surface of the holding plate 5a. Can move up and down even when a slight force is applied.

Next, a method for sealing the EL element shown in FIGS. 6 and 7 will be described using the above-described apparatus. Only operations different from those of the embodiment shown in FIGS. 1 to 5 will be described. First, in the initial state in which the cover plate 3 is sucked and held on the lower surface of the upper surface plate B, as shown by the solid line in FIG. The elastic member 6 is shortened by the weight of 3, and the upper stool B is slightly lowered and balanced. Then, the lowering of the upper surface plate B is started by the operation of the driving source C3 of the lifting / lowering means C, and as shown by the two-dot chain line in FIG. The small amount of sealant 4b and the large amount of sealant 4a are attracted to each other so that the cover plate 3 is lowered. The elastic member 6 is shortened by this downward pulling force, and the cover plate 3 is pulled down faster than the descending speed by the elevating means C. As a result, the cover plate 3 moves downward following the attraction between the small amount of sealant 4b and the large amount of sealant 4a, so that no gap is formed between the small amount of sealant 4b and the large amount of sealant 4a. Air is completely prevented from entering the space, and no air bubbles are generated in the sealant 4. Subsequent sealant 4
As the cover spreads, the cover plate 3 is slightly pulled downward, and the elastic member 6 is further shortened.
Is adjusted to promote the spread of the sealant 4 due to the capillary phenomenon. Thereby, the spread of the sealant 4 is further accelerated and is performed smoothly. Further, the driving source C3 of the lifting / lowering means C
Even if the upper platen B is lowered too much as shown by the solid line in FIG. 7, the elastic member 6 is extended by the spread sealant 4 and pushes the cover plate 3 upward. Thereby, the weight of the cover plate 3 and the reaction force received from the sealant 4 are balanced, and the cover plate 3 and the transparent substrate 2 are maintained at a predetermined gap G thickness (for example, 20 to 50 μm). As a result, the sealant 4 is crushed more than necessary by the cover plate 3 and does not protrude.

6 and 7, the amount of the adsorbing member is determined more irrespective of the shape of the sealant after application and the thickness error of the transparent substrate and the cover plate than in the embodiment shown in FIGS. There is an advantage that the sealing operation can be completed without lowering the air and without protruding just by lowering.

In the embodiment shown in FIGS. 6 and 7, when the size of the cover plate 3 is small, a plurality or a single suction pad is supported so as to be vertically movable instead of the upper surface plate B. The same operation and effect can be obtained.

In the embodiment shown in FIGS. 6 and 7,
A large amount of sealant 4a dispersedly applied to the central portion and the outer peripheral portion of the transparent substrate 2 described in the embodiment shown in FIGS.
And a small amount of sealant 4b applied to the central portion and the outer peripheral portion of the cover plate 3 at a single point, respectively. However, as shown in FIG. The sealant 4 applied by pressing may be spread by the cover plate 3. In this case, at the moment when the cover plate 3 comes into contact with the flat upper end surface of the sealant 4, even if the sealant 4 is suddenly crushed, the seal plate 4 is pulled by the cover plate 3 and the cover plate 3 is an upper surface plate B which is an adsorption member. Therefore, no gap is generated between the two following the sudden change in the shape of the sealant 4, and the sealant 4 is not crushed more than necessary by the cover plate 3 and does not protrude. As a result, as compared with the case shown in FIG. 8, the lower cover plate 3 reduces the adsorbing member by a fixed amount, regardless of the sealant shape after application and the thickness error of the transparent substrate and the cover plate. There is an advantage that the sealing operation can be completed without causing the occurrence.

In the above-described embodiments, the cover plates 3 are disposed above the transparent substrate 2 so as to face each other. However, the present invention is not limited to this. Then, the transparent substrate 2 is arranged, and a large amount of the sealant 4a is dispersed and applied to the central portion and the outer peripheral portion of the cover plate 3, and a small amount of the sealant 4b is applied to the central portion and the outer peripheral portion of the transparent substrate 2. May be. Further, the lifting / lowering means C is not limited to the one described above, and may have another configuration as long as the same operation is performed. In addition, if the sealant 4 which does not change its properties even in a vacuum is used in both of the above-described embodiments, the space for expanding the sealant 4 is set to a vacuum of 2000 Pa or less. Even better results are obtained.

[0028]

As described above, according to the first aspect of the present invention, the transparent substrate and the cover plate are brought close to each other by the operation of the lifting / lowering means, whereby the substantially flat upper end of the large amount of sealant is provided. A small amount of sealant hanging in an inverted chevron starts contact at each point and spreads in a substantially uniform amount, and then all of these sealants merge to reach the peripheral edge of the cover plate or the transparent substrate. In addition, the sealant can be spread over the entire area in a short time while preventing the intrusion and protrusion of air. Therefore, compared with the conventional method in which the sealant is radially spread out from the center of the transparent substrate and spread to the peripheral edge by capillary action, the sealant reaches all corners of the peripheral edge in a short time, as a result, the The takt time can be shortened, so that it is not necessary to increase the number of devices or install a buffer or the like which waits until the spreading of the sealant is completed. Furthermore, the sealant spreads in a substantially uniform amount in the middle area of each side where the radial distance is shorter than the outer four corners, as compared with the conventional method in which the sealant is likely to protrude. Without
Accordingly, there is no need to provide a frame for preventing the sealant from protruding around the EL element layer, so that the cost of the product can be reduced and a high-quality EL display panel can be provided. In addition, the cover plate does not make surface contact with the flat upper end surface of the sealant, as compared with the conventional method in which the cover plate that has descended while being horizontal remains in contact with the flat upper end surface of the sealant applied on the transparent substrate. Therefore, it is possible to prevent bubbles from being generated between the cover plate and the EL element, thereby preventing the EL element from deteriorating and the quality of the EL display panel from deteriorating.

[0029]

[0030]

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of an EL element sealing method according to an embodiment of the present invention, and shows a solid line before a suction member descends.

FIG. 2 is a partial cross-sectional plan view taken along the line (2)-(2) of FIG. 1, wherein (a) shows a state before the inflow of a sealant;
(B) shows the state after the sealant has joined.

FIG. 3 is a partial cross-sectional plan view showing a variation of a dispersion position of a sealant, (a) showing a state before the sealant flows,
(B) shows the state after the sealant has joined.

FIG. 4 is a partial cross-sectional plan view showing a modification of the dispersion position of the sealant, (a) showing before the inflow of the sealant,
(B) shows the state after the sealant has joined.

FIG. 5 is a partially cutaway front view showing the completion of the lowering of the suction member by a solid line.

FIG. 6 is a partially cutaway front view of an EL element sealing device according to another embodiment of the present invention, in which an initial state before a suction member descends is indicated by a solid line.

FIG. 7 is a partially cutaway front view showing the completion of the lowering of the suction member.

FIG. 8 is an example of a conventional EL element sealing method, in which (a) is a partially cutaway front view showing a state before the suction member descends by a solid line,
(B) is a partial enlarged cross-sectional plan view of the same state.

[Explanation of symbols]

A surface plate (lower surface plate) B adsorption member (upper surface plate) C lifting / lowering means 1 EL element layer 2 transparent substrate 3 cover plate 4 sealant 4a large sealant 4b small sealant 6 elastic member

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-11-283739 (JP, A) JP-A-10-3355061 (JP, A) JP-A-62-22393 (JP, A) JP-A-7-27 320865 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05B 33/00-33/28

Claims (1)

(57) [Claims] A liquid sealant (4) is applied between a transparent substrate (2) on which a rectangular electroluminescent element layer (1) is formed and a cover plate (3), and the transparent substrate ( By moving the suction member (B), which holds one of the cover plate (3) by suction and holding, with respect to the surface plate (A) on which one of the cover plate (3) and the cover plate (3) is held by the lifting means (C), In the method of sealing the electroluminescent element layer (2) by expanding the sealant (4), either the transparent substrate (2) or the cover plate (3) sucked and held on the surface plate (A). A large amount of a sealant (4) is dispersed and applied at appropriate intervals to one central portion and the outer peripheral portion, and the other of the cover plate (3) or the transparent substrate (2) which is adsorbed and held by the adsorbing member (B). In a position opposite to the large amount of sealant (4a), a small amount of sealant (4b And a step of bringing the upper end portion of the large amount of sealant (4a) into close contact with the sealant (4b) hanging down in an inverted mountain shape by means of a lifting / lowering means (C). A method of sealing an electroluminescent element.