WO2005036935A1

WO2005036935A1 - Double-sided organic electroluminescent display

Info

Publication number: WO2005036935A1
Application number: PCT/KR2004/002575
Authority: WO
Inventors: Han Sung Yu
Original assignee: SKC Co Ltd
Current assignee: SKC Co Ltd
Priority date: 2003-10-10
Filing date: 2004-10-08
Publication date: 2005-04-21
Anticipated expiration: 2006-04-10
Also published as: KR100934155B1; KR20050034878A

Abstract

A double-sided organic electroluminescent display (100) includes a first organic electroluminescent display (10), a second organic electroluminescent display (20), and a joining assembly (5). The first organic electroluminescent display (10) includes a first substrate (11) for forming a display surface, a first display region (15) configured to include a first light emission element, and a first circuit part (13) for supplying power. The second organic electroluminescent display (20) includes a second substrate (21) for forming a display surface, a second display region (25) configured to include a second light emission element, and a second circuit part (23) for supplying power to the second display region (25). The joining assembly (5) joins the first and second organic electroluminescent displays (10, 20) together.

Description

DOUBLE-SIDED ORGANIC ELECTROLUMINESCENT DISPLAY

Technical Field The present invention relates to a double-sided organic electroluminescent display; and more particularly, to a double-sided electroluminescent display that is capable of displaying independent images on both sides thereof, respectively, and is suitable for the realization of the low weight and thinness.

Background Art

Electroluminescent displays are self emission type displays. Since the electroluminescent displays have the advantages of a wide viewing angle, superior contrast and high response speed, the electroluminescent displays are being spotlighted as next generation displays. The electroluminescent displays are classified into inorganic electroluminescent displays and organic electroluminescent displays according to material that constitutes a light emission layer. An organic electroluminescent display includes a substrate made of a transparent glass or a plastic plate, a first electrode formed on the substrate, an organic film in which a hole transfer layer, an organic light emission layer and electron transfer layer are sequentially stacked one on top of another, and a second electrode formed on the organic film. In the organic electroluminescent display having the above configuration, light is emitted by the recombination of holes, which have been injected into the hole transfer layer, and electrons, which have been injected into the electron transfer layer, when an electric potential difference is applied between the first and second electrodes . Recently, research on double-sided organic electroluminescent display capable of displaying images on both sides thereof has been conducted. A double-sided organic electroluminescent display disclosed in Japanese Unexamined Pat. Publication No. 2001-332392 is constructed in such a way that an electron transfer layer, an organic light emission layer and a hole transfer layer are stacked one on top of another between an opaque cathode and a transparent anode and a transparent member is formed in a portion of the opaque cathode as a light guide part. The double-sided electroluminescent display constructed as described above allows an image, generated by a single organic electroluminescent display, to be displayed on both sides of the display at the same time. However, the double-sided electroluminescent display disclosed in Japanese Unexamined Patent Publication No. 2001-332392 is disadvantageous in that independent images cannot be displayed on both sides thereof at the same time. In order to solve the above-described problem, there has been proposed a technology of displaying different images on both sides of a single organic electroluminescent display by joining together different sealed organic electroluminescent displays with the backs thereof opposite to each other. However, this organic electroluminescent display has a limitation in the realization of thinness due to an excessive space required for the formation of a sealed structure, and a limitation in the realization of low weight of an organic electroluminescent display due to the excessive weight of a sealing member.

Disclosure of Invention

It is, therefore, an object of the present invention to provide a double-sided organic electroluminescent display that is capable of displaying independent images on both sides thereof. It is another object of the present invention to provide a double-sided organic electroluminescent display that is suitable for the realization of low weight and thinness. • It is still anther object of the present invention to provide a double-sided organic electroluminescent display that has an improved support structure, thus providing improved reliability. In accordance with the present invention, there is provided a double-sided organic electroluminescent display including: a first organic electroluminescent display including a first substrate for forming a display surface for a first image, a first display region configured to include a first light emission element, and a first circuit part for supplying power to the first display region; a second organic electroluminescent display placed to be opposite to the first organic electroluminescent display, the second organic electroluminescent display including a second substrate for forming a display surface for a second image-, a second display region configured to include a second light emission element, and a second circuit part for supplying power to the second display region; and a joining assembly for joining the first and second organic electroluminescent displays together to seal the first and second display regions. The joining assembly includes a spacer interposed between the first and second organic electroluminescent displays and a hardening bonding material applied around the spacer. The organic electroluminescent display further includes an absorbent material inside the sealed first and second organic electroluminescent displays. The area of the first display region is larger than that of the second display region, and the absorbent material is placed around the second display region. The area of the first display region is larger than that of the second display region, and the second circuit part is directly mounted on the second substrate. At least one of the first circuit part and the second circuit part is placed outside the first and second organic electroluminescent displays joined together, and the first or second circuit part placed outside the first and second organic electroluminescent displays is directly mounted on at least one of its corresponding first or second substrate.

Brief description of Drawings The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which: Fig. 1 is a sectional view of a double-sided organic electroluminescent display according to a preferred embodiment of the present invention; and Figs. 2 to 5 are sectional views of double-sided organic electroluminescent displays according to the other embodiments of the present invention.

Best Mode for Carrying Out the Invention

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein like parts appearing in Figs. 2 to 5 are represented by like reference numerals. Fig. 1 is a sectional view of a double-sided organic electroluminescent display according to a preferred embodiment of the present invention. Figs. 2 to 5 are sectional views of double-sided organic electroluminescent displays according to the other embodiments of the present invention. Referring to Fig. 1, a double-sided organic electroluminescent display 100 includes a first organic electroluminescent display 10, a second organic electroluminescent display 20 and a joining assembly 5. The first organic electroluminescent display 10 includes a first substrate 11, a first display region 15 formed on the first substrate 11, a first circuit part 13, and a first wiring part 17. The first substrate 11 is used as a surface for displaying an image, and is formed of a plate made of transparent glass to transmit light. The first display region 15 is placed approximately at the center of the first substrate 11. The first display region 15, including a light emission part (not shown) , is used as an image display part for displaying an image. The first circuit part 13 includes a vertical circuit part (not shown) and a horizontal circuit part (not shown) and is placed around the first display region 15. The first wiring part 17 is placed around the other side of the first display region 15. A main function of the first circuit part 13 and the first wiring part 17 is to supply controlled power to the light emission part. The second organic electroluminescent display 20 includes a second substrate 21, a first display region 25 formed on the second substrate 21, a second circuit part 23, and a second wiring part 27. The second organic electroluminescent display 20 has substantially the same structure as the first organic electroluminescent display 20. The second substrate 21 is formed of a transparent glass plate to transmit light, and the second display region 25 is placed approximately at the center of the second substrate 21. The second circuit part 23, including a vertical circuit part (not shown) and a horizontal circuit part (not shown) , and the second wiring part 27 are placed around the second display region 25. The first and second electroluminescent displays 10 and 20 constructed as described above are joined by the joining assembly 5, with the backs thereof being opposite to each other. The joining assembly 5 includes a spacer ϊ and a hardening adhesive agent 2. The spacer 1 is placed between the outer sides of the first and second substrates 11 and 21 joined together, and the hardening bonding material 2 is applied around the spacer 1 to surround the spacer 1. The spacer 1 is preferably formed to have a size greater than a specific value so as to prevent the display regions 15 and 25, the circuit parts 13 and 23_ and the wiring parts 17 and 27, which are placed on the first and second substrates 11 and 21, from being damaged when the first and second organic electroluminescent displays 10 and 20 are joined together. In this case, the spacer 1 may be formed in a formal body having a specific shape. The spacer 1 may be formed in consideration of support strength, for example, a cross- shaped formal body. The spacer 1 may be made of material such as glass or ceramic. The hardening adhesive agent 2 may be, for example, thermosetting resin or ultraviolet-curable resin. Fig. 2 is a sectional view of a double-sided organic electroluminescent display 100 according to another embodiment of the present invention. As shown in Fig. 2, a first organic electroluminescent display 10 and a second organic electroluminescent display 20 are joined by a joining assembly 5 located therebetween, with the backs thereof being opposite to each other. The joining assembly 5 includes a spacer 1 and a hardening adhesive agent 2. The spacer 1 is interposed between first and second circuit parts 13 and 23 which are placed around first and second display regions 15 and 25, respectively and between first and second wiring parts 17 and .27 which are placed around another side of the first and the second display regions 15 and 25, respectively. A hardening adhesive agent 2 is applied around the spacer 1, so that the first and second organic electroluminescent displays 10 and 20 are joined together. Fig. 3 shows a double-sided organic electroluminescent display according to another embodiment of the present invention. The double-sided organic electroluminescent display shown in Fig. 3 has the same arrangement as that shown in Fig. 1 excepting those as follows. As shown in Fig. 3, a first display region 15 of a first substrate 11 is formed over an area larger than that over which a second display region 25 of a second substrate 21 is formed. An absorbent material 30 is provided in the second substrate 21, so that the organic films of the first and second display regions 15 and 25 can be protected from moisture. The absorbent material 30 is filled in a space that is formed by partially etching the second substrate 21. Fig. 4 is a sectional view of an organic electroluminescent display according to another embodiment of the present invention. The double-sided organic electroluminescent display shown in Fig. 4 has the same arrangement as that shown in Fig. 1 excepting those as follows. As shown in Fig. 4, a first substrate 11 is longer than a second substrate 13, and vice versa. A first circuit part 13 is placed outside a space sealed by the first and the second substrates 11 and 21. In this case, a driving Integrated Circuit (IC: not shown) for a first circuit part 13 may be directly mounted on the first substrate 11 through a Chip On Glass (COG) fashion without mounting separate surface mounting parts. Meanwhile, when internal wiring connecting the driving IC to the display regions is formed in a multi-layer structure, line resistance can be reduced. Moreover, in this embodiment, since the circuit part 13 is located outside the sealed area, the area of the display region 15 can be increased. Fig. 5 is a sectional view showing a double-sided organic electroluminescent display according to another embodiment of the present invention. The present embodiment has the same construction as the above-described embodiment except that a joining assembly 5 is placed behind first and second display regions 15 and 25. In more detail, as shown in Fig. 5, the joining assembly 5 includes a spacer 1 and a hardening adhesive agent 2, and the spacer 1 and the hardening adhesive agent 2 are formed between the first and second display regions 15 and 25. In this case, a sealing material 40 is applied to the outer sides of the first and second substrates 11 and 21 joined together to protect organic films (not shown) formed in the interiors of the first and second display regions 15 and 25. The spacer 1 may be made of material such as a glass or a ceramic. Alternatively, the spacer 1 may be integrated with a connection member (not shown) to the display regions into a single body, and be interposed between the first and second display regions 15 and 25. In this case, the spacer 1 can be integrally handled, so that a process of manufacturing an organic electroluminescent display can be easily carried out. The spacer 1 formed between the display regions may be arranged in one of various patterns, such as a rod-shaped pattern, a grating-shaped pattern and an uneven pattern. A hardening adhesive agent 2 is applied around the spacer 1 to surround the spacer 1, and thermosetting resin and UV-curable resin may be used as the hardening adhesive agent 2. In the above embodiment, protective films (not shown) may be additionally formed on the first and second display regions 15 and 25 in contact with the spacer 1 to protect the first and second display regions 15 and 25. The protective films may be made of inorganic or organic material . Alternatively, the first and second display regions 15 and 25 may be sealed by the spacer 1 and the hardening adhesive agent 2 without using the sealing material 40. As described above, according to the present invention, since the first and second organic electroluminescent displays 10 and 20 can be operated individually, independent images can be displayed on both sides of the organic electroluminescent display 100. Furthermore, additional encapsulation structures are not required to protect the internal components of the display, and the first and second substrates 11 and 21 function as the encapsulation structure. Accordingly, the double-sided electroluminescent display allows the number of components to be reduced compared to a conventional double- sided organic electroluminescent display in which two organic electroluminescent displays having separate encapsulation structures are simply joined together, so that the reduction of manufacturing costs and the low weight of the display can be achieved. Moreover, since a space for the separate encapsulation structures is not needed, the thinness of a double-sided electroluminescent display can be realized. Moreover, when the spacer 1 constituting a part of the joining assembly 5 is interposed between the first and second organic electroluminescent displays 10 and 20, the gap between the first and second organic electroluminescent displays 10 and 20 can be kept constant, so that the bending and twisting of the entire display can be prevented, thus providing the display suitable for the implementation of a large-sized display. When the circuit part or circuit parts 13 and/or 23 of the first and/or second organic electroluminescent displays 10 and 20 of the present invention is mounted in a COG fashion, a COG type display without mounting separate surface mounting parts can be implemented. In particular, when the circuit part or circuit parts 13 and/or 23 are mounted in the area other than the area sealed by the first and second substrates 11 and 21, the area of the display regions 13 and 23 can increase. While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims .

Claims

1. A double-sided organic electroluminescent display comprising: a first organic electroluminescent display including a first substrate for forming a display surface for a first image, a first display region configured to include a first light emission element, and a first circuit part for supplying power to the first display region; a second organic electroluminescent display placed to be opposite to the first organic electroluminescent display, the second organic electroluminescent display including a second substrate for forming a display surface for a second image, a second display region configured to include a second light emission element, and a second circuit part for supplying power to the second display region; and joining means for joining the first and second organic electroluminescent displays together to seal the first and second display regions.

2. The organic electroluminescent display as set forth in claim 1, wherein the joining means includes a spacer interposed between the first and second organic electroluminescent displays and a hardening adhesive agent applied around the spacer.

3. The organic electroluminescent display as set forth in claim 1, further comprising an absorbent material inside the sealed first and second organic electroluminescent displays.

4. The organic electroluminescent display as set forth in claim 3, wherein an area of the first display region is larger than that of the second display region, and the absorbent material is placed around the second display region.

5. The organic electroluminescent display as set forth in claim 1, wherein an area of the first display region is larger than that of the second display region, and the second circuit part is directly mounted on the second substrate .

6. The organic electroluminescent display as set forth in claim 1, wherein at least one of the first circuit part and the second circuit part is placed outside the first and second organic electroluminescent displays joined together, and the first or second circuit part placed outside the first and second organic electroluminescent displays is directly mounted on at least one of its corresponding first or second substrate.

7. The organic electroluminescent display as set forth in claim 1, wherein the first and second images are different from each other.

8. The organic electroluminescent display as set forth in claim 1, wherein the first and second images are same with each other.

9. The organic electroluminescent display as set forth in claim 1, wherein the first and second electroluminescent displays are joined with the backs thereof being opposite to each other.

10. The organic electroluminescent display as set forth in claim 1, wherein the spacer is placed between the outer sides of the first and second substrates joined together.

11. The organic electroluminescent display as set forth in claim 1, wherein the spacer is placed between the first and the second display regions of the first and second substrates joined together.