Electro luminescence display device

An electro luminescence display device is adapted for preventing the deterioration of an organic light-emitting layer by ultraviolet rays during a sealing process, and a transparent substrate; an organic light-emitting layer formed on the transparent substrate; a packaging plate bonded with the transparent substrate by a sealant to cover the organic light-emitting layer; and a light-intercepting member to prevent ultraviolet rays illuminated onto the sealant during bonding the transparent substrate with the packaging plate from being reflected by the packaging plate onto the organic light-emitting layer.

This application claims the benefit of Korean Patent Application No. P2003-73310 filed in Korea on Oct. 21, 2003, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electro luminescence display device, and more particularly to an electro luminescence display device that is adaptive for preventing the deterioration of an organic light-emitting layer by ultraviolet ray in a sealing process.

2. Description of the Related Art

Recently, there have been highlighted various flat panel display devices that are capable of reducing their weight and bulk which are disadvantages of a cathode ray tube (CRT). Such flat panel display devices include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP) and an electro-luminescence (EL) display, etc.

The EL display in such display devices is a self-luminous device that makes a phosphorous material to emit light by a re-combination of electrons and holes. The EL display device is generally classified into an inorganic EL device using an inorganic compound as the phosphorous material and an organic EL using an organic compound as the phosphorus material. Such an EL display device has many advantages of a low voltage driving, a self-luminescence, a thin-thickness, a wide viewing angle, a fast response speed, a high contrast and so on such that it has been highlighted as a post-generation display device.

The organic EL device is comprised of an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer and a hole injection layer. In such an organic EL device, when a predetermined voltage is applied between an anode and a cathode, electrons generated from the cathode move to the light-emitting layer through the electron injection layer and the electron transport layer, while holes generated from the anode move to the light-emitting layer through the hole injection layer and the hole transport layer. Accordingly, the electrons and the holes fed from the electron transport layer and the hole transport layer are re-combined to emit light.

Referring toFIG. 1, an EL display device of prior art includes a transparent substrate2, an organic light-emitting layer18formed on the transparent substrate2, a packaging plate24to seal off the organic light-emitting layer18on the transparent substrate2, and a sealant22to bond the packaging plate24with the transparent substrate2.

The organic light-emitting layer18includes an electron injection layer, an electron transport layer, alight-emitting layer, a hole transport layer and a hole injection layer that are deposited between an anode and a cathode (not shown). In the organic light-emitting layer18, if voltage is applied between a transparent electrode as the anode and a metal electrode as the cathode, the electrons generated from the cathode move to the light-emitting layer through the electron injection layer and the electron transport layer, and the holes generated from the anode move to the light emitting layer through the hole injection layer and the hole transport layer. Accordingly, in the light-emitting layer, the electrons and the holes supplied from the electron transport layer and the hole transport layer collide with each other to be recombined, thereby generating light. The light is emitted to the outside through the anode, the transparent electrode, to display a picture.

The packaging plate24absorbs moisture and oxygen in the air, so a hygroscopic film27is stuck to the packaging plate24in order to protect the organic light-emitting layer18from the moisture and oxygen in the air. For this, the packaging plate24includes a stepped part30having an incline plane26and a horizontal plane. The stepped part30provides an inner space, where the hygroscopic film27is stuck, in the central part of the packaging plate24.

The sealant22is spread between the transparent substrate2and the most outer stepped plane28of the packaging plate24, and then it is hardened by illuminating it with ultraviolet rays, thereby bonding the packaging plate24with the transparent substrate2. The packaging plate24seals up the organic light-emitting layer18by being bonded with the transparent substrate2by the sealant22in a vacuum state.

The electro luminescence display device of the related art, as shown inFIG. 2, bonds the transparent substrate2with the packaging plate24by a bonding device.

More specifically, the bonding device includes a large transparent substrate2where a plurality of organic light-emitting layers18are formed and which is fixed by a fixing means (not shown); a plurality of absorbers50to which a plurality of packaging plates24are absorbed, wherein the packaging plates24are bonded with the transparent substrate2; a sealant22spread at the edge of the transparent substrate2or the packaging plate24; an UV illuminating device60to illuminate an ultraviolet ray62to the sealant24; and a mask64to mask other area than the sealant24in order that the ultraviolet ray62is not illuminated onto each organic light-emitting layer18.

The absorbers50absorb the packaging plate24supplied from the outside, using a pad52.

The absorber50has the packaging plate24absorbed on a pad52thereof and has the transparent substrate fixed thereto by a fixing means to align the organic light-emitting layer18formed on the transparent substrate2and the packaging plate24.

And then, the ultraviolet ray62from the UV illuminating device60is illuminated onto the sealant22spread between the transparent substrate2and the packaging plate24for a designated time. At this moment, the mask64allows the ultraviolet rays62illuminated from the UV illuminating device60to be illuminated only on the sealant22spread between the transparent substrate2and the packaging plate24, and the ultraviolet ray62is intercepted at the remaining areas.

Accordingly, the sealant22is hardened by the ultraviolet ray62illuminated through the mask64to bond the transparent substrate2with the packaging plate24.

During the bonding of the transparent substrate2with the packaging plate24the ultraviolet rays64are illuminated onto the sealant22through the mask64, as shown inFIG. 3. However, some ultraviolet rays64are reflected by the incline plane26of the stepped plane30formed at the packaging plate24to generate a reflected light70. That is, the ultraviolet ray64is illuminated onto the sealant22to harden the sealant22, and at the same time, is dispersed by the incline plane26of the stepped part30formed at the packaging plate24to generate the reflected light70. The reflected light70may even be reflected over and over between the transparent substrate2and the incline plane26and the stepped plane28of the stepped part30of the packaging plate24. This reflected ultraviolet light can illuminate onto the surrounding area of the organic light-emitting layer18of the EL display device. This reflected light70illuminated on to the organic light-emitting layer18deteriorates the organic light-emitting layer18, and in addition, is illuminated onto the surrounding areas of the EL display device to change the characteristics of the driving devices, such as the transistor of the surrounding circuit of the EL display device.

Accordingly, the EL display device of related art has the edge of the organic light-emitting layer18deteriorated by the reflected light70which is caused by the reflection/dispersion of ultraviolet rays64illuminated onto the sealant22during the bonding process of the transparent substrate2and the packaging plate24. Further, the reflected lights can change the characteristics of the driving devices of the surrounding circuit, thereby causing a brightness difference between the central part80of the EL display device and the other areas82, as shown inFIG. 4.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an electro luminescence display device that is adapted for preventing the deterioration of an organic light-emitting layer by ultraviolet ray in a sealing process.

In order to achieve these and other objects of the invention, an electro luminescence display device according to an aspect of the present invention includes a transparent substrate; an organic light-emitting layer formed on the transparent substrate; a packaging plate bonded with the transparent substrate by a sealant to cover the organic light-emitting layer; and a light-intercepting member to prevent the ultraviolet rays, illuminated onto the sealant during bonding of the transparent substrate with the packaging plate, from being reflected by the packaging plate to illuminate the organic light-emitting layer.

The light-intercepting member is a light-intercepting projected part which is projected toward the transparent substrate from the packaging plate.

The light-intercepting projected part is located between the sealant and the organic light-emitting layer.

The light-intercepting projected part is projected from the packaging plate to be as close as possible to the organic light-emitting layer.

The light-intercepting projected part is formed to have a section of any one shape between a quadrangle and a triangle.

The light-intercepting member is a plurality of light-intercepting projected parts that are projected toward the packaging plate from the transparent substrate.

The light-intercepting projected parts are formed between the organic light-emitting layer and the end of the transparent substrate.

Each of the light-intercepting projected parts is formed to have a section of any one shape between a quadrangle and a triangle.

The light-intercepting member is an ultraviolet absorbing layer that is formed on the packaging plate to be opposite the transparent substrate and absorbs the ultraviolet rays.

The ultraviolet absorbing layer is formed at the edge of the packaging plate so as to be opposite between the end of the transparent substrate and the edge of the organic light-emitting layer, and in addition, to overlap the edge of the organic light-emitting layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference toFIGS. 5 to 10.

Referring toFIG. 5, an electro luminescence display device according to a first embodiment of the present invention includes a transparent substrate102; an organic light-emitting layer118formed on the transparent substrate102; a packaging plate124to seal off the organic light-emitting layer118on the transparent substrate102; a sealant122to bond the packaging plate124with the transparent substrate102; and at least one light-intercepting projected part140formed at the packaging plate124to prevent an ultraviolet ray, illuminated onto the sealant122upon bonding the packaging plate124with the transparent substrate102, from reflecting onto the light-emitting layer118.

The organic light-emitting layer118includes an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer and a hole injection layer that are deposited between an anode and a cathode (not shown). In the organic light-emitting layer118, if voltage is applied between a transparent electrode as the anode and a metal electrode as the cathode, the electrons generated from the cathode move to the light-emitting layer through the electron injection layer and the electron transport layer, and the holes generated from the anode move to the light emitting layer through the hole injection layer and the hole transport layer. Accordingly, in the light-emitting layer, the electrons and the holes supplied from the electron transport layer and the hole transport layer collide with each other to be recombined, thereby generating light. The light is emitted to the outside through the anode, the transparent electrode, to display a picture.

The packaging plate124is bonded with the transparent substrate102by the sealant122to cover the organic light-emitting layer118. The packaging plate124absorbs moisture and oxygen in the air, so a hygroscopic film127is stuck to the packaging plate124in order to protect the organic light-emitting layer118from the moisture and oxygen in the air. For this, the packaging plate124includes a stepped part130having an incline plane126and a horizontal plane128. The stepped part130provides an inner space, where the hygroscopic film127is stuck, in the central part of the packaging plate124.

The sealant122is spread between the transparent substrate102and the most outer stepped plane128of the packaging plate124, and then it is hardened by illuminating it with ultraviolet rays, thereby bonding the packaging plate124with the transparent substrate102. The packaging plate124seals up the organic light-emitting layer118by being bonded with the transparent substrate102by the sealant122in a vacuum state.

The at least one light-intercepting projected part140is projected toward the transparent substrate102and has a section of any one shape of a quadrangle and a triangle. The at least one light-intercepting projected part140exists between the sealant122and the organic light-emitting layer118. The light-intercepting projected part140is projected to be as close to the organic light-emitting layer118as possible, and in addition, to have a designated gap with the transparent substrate102.

The light-intercepting projected part140prevents the ultraviolet rays, illuminated onto the sealant122during the bonding process of the transparent substrate102and the packaging plate124, from being reflected by the incline plane126of the packaging plate124onto the organic light-emitting layer118and onto the driving devices of the surrounding area of the EL display device.

More specifically, the electro luminescence display device according to the first embodiment of the present invention allows for the illumination of ultraviolet rays onto the sealant122, spread at the edge of the packaging plate124, to harden the sealant122, and thereby bond the transparent substrate102with the packaging plate124. The light-intercepting projected part140, as shown inFIG. 6, prevents light170from the ultraviolet rays, which is illuminated onto the sealant122, from being reflected by the incline plane126of the packaging plate124onto the organic light-emitting layer118and the driving devices of the surrounding part of the EL display device. Accordingly, the electro luminescence display device according to the first embodiment of the present invention can prevent the deterioration of the organic light-emitting layer118and characteristic changes of the driving devices of the surrounding part of the EL display device caused by the reflected light170.

Referring toFIG. 7, an electro luminescence display device according to a second embodiment of the present invention includes a transparent substrate202; an organic light-emitting layer218formed on the transparent substrate202; a packaging plate224to seal off the organic light-emitting layer218on the transparent substrate202; a sealant222to bond the packaging plate224with the transparent substrate202; and a plurality of light-intercepting projected parts240projected toward the packaging plate224from the transparent substrate202to prevent a reflected light caused by the dispersion of ultraviolet rays from being illuminated onto the light-emitting layer218.

The organic light-emitting layer218includes an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer and a hole injection layer that are deposited between an anode and a cathode (not shown). In the organic light-emitting layer218, if voltage is applied between a transparent electrode as the anode and a metal electrode as the cathode, the electrons generated from the cathode move to the light-emitting layer through the electron injection layer and the electron transport layer, and the holes generated from the anode move to the light emitting layer through the hole injection layer and the hole transport layer. Accordingly, in the light-emitting layer, the electrons and the holes supplied from the electron transport layer and the hole transport layer collide with each other to be recombined, thereby generating light. The light is emitted to the outside through the anode, the transparent electrode, to display a picture.

The packaging plate224is bonded with the transparent substrate202by the sealant222to cover the organic light-emitting layer218. The packaging plate224absorbs moisture and oxygen in the air, so a hygroscopic film227is stuck to the packaging plate224in order to protect the organic light-emitting layer218from the moisture and oxygen in the air. For this, the packaging plate224includes a stepped part230having an incline plane226and a horizontal plane228. The stepped part230provides an inner space, where the hygroscopic film227is stuck, in the central part of the packaging plate224.

The sealant222is spread between the transparent substrate202and the most outer stepped plane228of the packaging plate224, and then it is hardened by illuminating it with ultraviolet rays thereby bonding the packaging plate224with the transparent substrate202. Hereby, the packaging plate224seals up the organic light-emitting layer218by being bonded with the transparent substrate202by the sealant222in a vacuum state.

The light-intercepting projected parts240are projected toward a transparent substrate202to have a section of any one shape of a quadrangle and a triangle at the edge of the transparent substrate202. In other words, the light-intercepting projected part240is formed between the organic light-emitting layer218and the end of the transparent substrate202, and the sealant222is spread on part of the light-intercepting projected part240.

The light-intercepting projected parts240prevent the ultraviolet rays, illuminated onto the sealant222during the bonding process of the transparent substrate202and the packaging plate224, from being reflected by the incline plane226of the packaging plate224onto the organic light-emitting layer218and onto the driving devices of the surrounding area of the EL display device.

More specifically, the electro luminescence display device according to the second embodiment of the present invention allows for the illumination of ultraviolet rays onto the sealant222, spread at the edge of the packaging plate224, to harden the sealant222, and thereby bond the transparent substrate202with the packaging plate224. The light-intercepting projected parts240, as shown inFIG. 8, prevents light270from the ultraviolet rays, which is illuminated onto the sealant222, from being reflected by the incline plane226of the packaging plate224onto the organic light-emitting layer218and the driving devices of the surrounding part of the EL display device. For this, the light-intercepting projected part240is projected from the transparent substrate202to be as close as possible to the packaging plate224to prevent the reflected light270from reaching the organic light-emitting layer218.

Accordingly, the electro luminescence display device according to the second embodiment of the present invention can prevent the deterioration of the organic light-emitting layer218and characteristic changes of the driving devices of the surrounding part of the EL display device caused by the reflected light270that is generated by the packaging plate224during the hardening of the sealant222.

Referring toFIG. 9, an electro luminescence display device according to a third embodiment of the present invention includes a transparent substrate302; an organic light-emitting layer318formed on the transparent substrate302; a packaging plate324to seal off the organic light-emitting layer318on the transparent substrate302; a sealant322to bond the packaging plate324with the transparent substrate302; and an ultraviolet ray absorbing layer340formed at the packaging plate324to prevent an ultraviolet ray illuminated onto the sealant322upon bonding the packaging plate324with the transparent substrate302, from being illuminated onto the light-emitting layer318.

The organic light-emitting layer318includes an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer and a hole injection layer that are deposited between an anode and a cathode (not shown). In the organic light-emitting layer318, if voltage is applied between a transparent electrode as the anode and a metal electrode as the cathode, the electrons generated from the cathode move to the light-emitting layer through the electron injection layer and the electron transport layer, and the holes generated from the anode move to the light emitting layer through the hole injection layer and the hole transport layer. Accordingly, in the light-emitting layer, the electrons and the holes supplied from the electron transport layer and the hole transport layer collide with each other to be recombined, thereby generating light. The light is emitted to the outside through the anode, the transparent electrode, to display a picture.

The packaging plate324is bonded with the transparent substrate302by the sealant322to cover the organic light-emitting layer318. The packaging plate324absorbs moisture and oxygen in the air, so a hygroscopic film327is stuck to the packaging plate324in order to protect the organic light-emitting layer318from the moisture and oxygen in the air. For this, the packaging plate324includes a stepped part330having an incline plane326and a horizontal plane328. The stepped part330provides an inner space, where the hygroscopic film327is stuck, in the central part of the packaging plate324.

The sealant322is spread between the transparent substrate302and the most outer stepped plane328of the packaging plate324, and then it is hardened by illuminating it with ultraviolet rays, thereby bonding the packaging plate324with the transparent substrate302. Hereby, the packaging plate324seals up the organic light-emitting layer318by being bonded with the transparent substrate302by the sealant322in a vacuum state.

The ultraviolet absorbing layer340is formed at the horizontal plane328of the incline plane326along the edge of the packaging plate324that corresponds to the edge of the transparent substrate302. In other words, the ultraviolet absorbing layer340is formed at the rear surface of the packaging plate324to face to an area between the end of the transparent substrate302and the end of the organic light-emitting layer318. Also, the ultraviolet absorbing layer340is formed to overlap the edge area of the organic light-emitting layer318.

The ultraviolet absorbing layer340prevents the ultraviolet rays, illuminated onto the sealant322during the bonding process of the transparent substrate302and the packaging plate324, from being reflected by the incline plane326of the packaging plate324onto the organic light-emitting layer318and onto the driving devices of the surrounding area of the EL display device.

More specifically, the electro luminescence display device according to the third embodiment of the present invention allows for the illumination of ultraviolet rays onto the sealant322, spread at the edge of the packaging plate324, to harden the sealant322, and thereby bond the transparent substrate302with the packaging plate324. The ultraviolet absorbing layer340, as shown inFIG. 10, when the ultraviolet ray362is illuminated onto the sealant322, absorbs the ultraviolet ray362that would be reflected toward the organic light-emitting layer318by the incline plane326and the horizontal plane328of the packaging plate324. In other words, the ultraviolet absorbing layer340reduces the reflection efficiency of the stepped part330to prevent reflected light toward the organic light-emitting layer318. Accordingly, the electro luminescence display device according to the third embodiment of the present invention can prevent the deterioration of the organic light-emitting layer318and characteristic changes of the driving devices of the surrounding part of the EL display device caused by the reflected light370that is generated by the packaging plate324upon the hardening of the sealant322.

As described above, the electro luminescence display device according to the present invention includes the light-intercepting projected part which is projected toward the transparent substrate from the edge of the packaging plate. Accordingly, the present invention intercepts the ultraviolet ray which are illuminated onto the sealant upon bonding the transparent substrate with the packaging plate and reflected by the packaging plate toward the organic light-emitting layer, thereby preventing the deterioration of the organic light-emitting layer and characteristic changes of the driving devices of the surrounding part of the EL display device.

Further, the electro luminescence display device according to another embodiment of the present invention includes a plurality of light-intercepting projected parts which are projected toward the packaging plate from the edge of the transparent substrate. Accordingly, the present invention prevents the ultraviolet rays, which are illuminated onto the sealant during bonding the transparent substrate with the packaging plate, from being reflected onto the organic light-emitting layer, by use of the plurality of light-intercepting projected parts, thereby preventing the deterioration of the organic light-emitting layer and characteristic changes of the driving devices of the surrounding area of the EL display device.

Further, the electro luminescence display device according to another embodiment of the present invention includes the ultraviolet absorbing layer that is formed at the edge of the packaging plate. Accordingly, the present invention absorbs the ultraviolet ray, which is illuminated onto the sealant during bonding the transparent substrate with the packaging plate, and prevents reflection by the packaging plate onto the organic light-emitting layer, by use of the ultraviolet absorbing layer, thereby preventing the deterioration of the organic light-emitting layer and characteristic changes of the driving devices of the surrounding area of the EL display device.