1. Field of the Invention
The present invention relates to a liquid crystal display device for image display and the like.
2. Related Background Art
The characteristics required for the liquid crystal display device have become stricter in recent years. Now, the displayed image quality on such devices is required to be of the same level as in the ordinary CRT displays. Since the liquid crystal display device, the control of the orientation of the employed liquid crystal is a major factor governing the quality of the displayed image, uniform and optimum orientation in all parts of the display unit is essential. In general, orientation of the liquid crystal is controlled by an alignment control film provided on the surface of liquid crystal.
If such alignment control film has a surfacial step, the orientation of the liquid crystal varies (at such stepped portion) and is no longer uniform. However, the alignment control film particularly develops surfacial steps on the pixel electrode substrate because of the pixel electrodes, switching elements, wirings etc. on said substrate. Near the end of the display area, the film position becomes extremely low and the cell gap increases because of the absence of the adjacent pixel electrode, so that the display characteristics become inferior in such end portion of the display area.
Conventional liquid crystal display device is composed of two mutually adhered substrates bearing electrodes on the internal faces thereof and sandwiching a liquid crystal layer therebetween. Circuits for driving the liquid crystal device are often provided in the peripheral area of the pixel areas.
In the mutual adhesion of both substrates, if a seal area 32 is formed on the peripheral circuits 31 as shown in FIG. 1, there is generated a distribution in the gap of the filled liquid crystal part 33. Unevenness in color is generated if the distribution gap exceeds .+-.0.1.mu..
On the other hand, if the seal area 32 is provided outside the peripheral circuits 31 as shown in FIG. 2, the chip size becomes inevitably larger and cannot serve as a liquid crystal display device requiring a very small cell size, such as in a view finder.
There is also known a method of forming an insulating planarization film 34 as shown in FIG. 3, but such requires the additional step of forming the planarization film 34, which also requires that the applied voltage be increased if the insulating layer becomes thicker on the pixel electrode. Also in case the substrate is composed of monocrystalline silicon substrate, the peripheral circuit steps are large so that the planarization layer 34 must be particularly thick, and an even larger applied voltage is required.