In recent years, there is a strong desire for an increase in the size of television sets and display devices for displaying information. Representative examples of large-sized display devices are display devices in which self-emission elements such as light-emitting diodes (LEDs) are arranged in a matrix array and projection display devices; however, these have disadvantages in terms of image quality. Therefore, a further increase in the size of direct-viewing type liquid crystal display devices (LCDs) and plasma display devices (PDPs), which are capable of displaying with a high image quality, is being desired.
Since a direct-viewing type liquid crystal display device or a plasma display device is basically formed on a glass substrate, its screen size depends on the substrate size. Currently, the largest of glass substrates (mother substrates) that are used for the production of liquid crystal display devices are those of the eighth generation (2200 mm×2400 mm), and liquid crystal display devices whose diagonal is about 100 inches are being produced by using these substrates. The substrates that are available for mass production will become more increased in size, however at a slow rate. It is difficult to immediately provide display devices with the larger areas that are required on the current market.
Therefore, as a method of realizing a large-screen display device, there has been a conventional attempt of realizing a make-believe large-screen display device by arraying a plurality of display devices (which may be referred to as tiling). However, the tiling technique induces a problem of visible joints between the plurality of display devices. This problem will be described by taking a liquid crystal display device for example.
Note that a liquid crystal display device mainly includes a liquid crystal display panel, a backlight device, circuits for supplying various electrical signals to the liquid crystal display device, and a power supply, as well as a housing in which to accommodate these. The liquid crystal display panel is mainly composed of a pair of glass substrates and a liquid crystal layer interposed therebetween. On one of the glass substrates, a color filter layer and a counter electrode are formed, whereas on the other glass substrate, TFTs, bus lines, a driving circuit for supplying signals to them, and the like are formed. The screen size of a direct-viewing type liquid crystal display device is determined by the screen size of the liquid crystal display panel. The liquid crystal display panel has a display region which is composed of a plurality of pixels, and a frame region surrounding it. In the frame region, a sealing portion with which to attach the pair of substrates together and also seal and retain the liquid crystal layer, an implementation of driving circuitry for driving the pixels, and the like are formed.
Thus, since the frame region not contributing to any displaying exists in a liquid crystal display panel, when a large screen is constructed by arraying a plurality of liquid crystal display panels, the image will have joints. This problem is not limited to liquid crystal display devices, but is shared among direct-viewing type display devices, e.g., PDPs, organic EL display devices, and electrophoresis display devices.
Accordingly, Patent Documents 1 and 2 show constructions in which a translucent cover is provided on the front face of a display panel. A large part of the cover corresponding to the display region is made flat, so that the image appears substantially undistorted. On the other hand, portions of the cover corresponding to the frame region and the display region near the frame region are bent, so that light which is emitted from the portions of the display region near the frame region is refracted, thus enabling displaying with no joints even in the non-display region.
[Patent Document 1] Japanese Laid-Open Patent Publication No. 5-188873
[Patent Document 2] Japanese National Phase PCT Laid-Open Publication No. 2004-524551