An organic electro luminescence (EL) element is a current-driven type self-luminous device, which has advantages of low power consumption, high viewing angle, high contrast ratio, and the like, without a backlight, and it is considered to facilitate the ongoing development of flat panel displays.
An organic EL display apparatus using the above-described organic EL element forms a plurality of pixels by using sub-pixels of respective colors of red (R), green (G) and blue (B), and whereby displays a variety of color images thereon. As a method of displaying these color images, there are a color filter type that produces three colors of R, G and B by a color filter, and a side-by-side selective deposition type that selectively deposits organic materials of three colors of R, G and B with individually different colors, based on a white organic EL element. The color filter type has a drawback in that the color filter absorbs light, reduces the utilization rate of light, and increases power consumption, whereas the side-by-side selective deposition type is an easy means to provide a wide color gamut due to high color purity, and the utilization rate of light is increased without a color filter. For this reasons, the side-by-side selective deposition type has been widely used.
When preparing the organic EL display apparatus using the above-described side-by-side selective deposition type, commonly, a switching element such as a thin film transistor (TFT) is formed on a glass substrate, and an organic EL element is formed thereon. However, by using a flexible plastic substrate instead of the glass substrate, a flexible organic EL display apparatus may be prepared. For example, a first thin film is formed on a plastic substrate, a switching element such as a TFT is formed thereon, an organic EL element is formed thereon, and then a second thin film is formed to seal the same, thereby a flexible organic EL display apparatus may be prepared. In this case, by successfully maintaining a deformation balance between the first thin film on the substrate side and the second thin film on the sealing side, it is possible to prepare an organic EL display apparatus foldable in a curvature exceeding about 2 mm (r>2 mm).
As a technique relating to the above-described foldable display apparatus, for example, Japanese Patent No. 3361820 discloses, as illustrated in FIGS. 1 to 3, a structure for installing a flexible liquid crystal display panel 502 comprising: a foldable-formed liquid crystal display panel installation member 501; and the flexible liquid crystal display panel 502 installed across a folding portion of the liquid crystal display panel installation member 501, wherein a bending part 502a is formed in the flexible liquid crystal display panel 502 during folding of the liquid crystal display panel installation member 501. In this structure, the vicinity of the bending part 502a of the flexible liquid crystal display panel 502 is configured to be free to the liquid crystal display panel installation member 501, and into a relief-groove part 503, which is formed on at least one surface of opposite surfaces, the bending part 502a is entered in the vicinity of the folding portion during folding of the liquid crystal display panel installation member 501.
In addition, Japanese Patent Laid-Open Publication No. 2006-287982 discloses, as illustrated in FIGS. 4 to 7, a structure which includes at least two substantially flat plate-shaped housings 511A and 511B, wherein the two flat plate-shaped housings 511A and 511B are connected to each other by a first connection means (hinge part) 513 in such a manner that, when these housings are bent toward each other, the respective flat surfaces thereof are opposed to each other with being separated from each other by as much as a thickness dimension of an electronic circuit housing 512, and the electronic circuit housing 512 and one housing of the flat plate-shaped housings 511A and 511B are connected to each other by a second connection means (hinge part) 514 in such a manner that, when the two flat plate-shaped housings 511A and 511B are mutually folded, the electronic circuit housing 512 is installed between the respective flat surfaces thereof.
Further, Japanese Unexamined Patent Application Publication No. 2008-507723 discloses, as illustrated in FIGS. 8 and 9, a portable display apparatus comprising: at least two or more panel housings 522 on which displays 521 are mounted; a folding type connection means 523 for connecting the panel housings 522; a circuit connection line which is mounted on the panel housings 522 to connect circuits of the displays 521; and a cover means 524 which cover the circuit connection line so as not to be exposed to an outside.
Further, Japanese Patent Laid-Open Publication No. 2006-174506 discloses, as illustrated in FIGS. 10 to 12, a portable communication terminal comprising: a substantially rectangular flexible display 531 having one bendable visible screen; a support housing group including two or more substantially flat plate-shaped support housings 532 connected to each other so as to be juxtaposed laterally as seen from a user; a substantially flat plate-shaped communication terminal housing (portable telephone housing) 533 connected to a right or left end part of the support housing group as seen from the user and including at least a wireless communication section, a voice input section and a voice output section; and a connection means (bending part) 534 which connects the communication terminal housing 533 to the support housing 532 adjacent thereto so as to be bent in a rear direction of the support housing 532 and so as to be folded with respect to the support housing 532.