As a method for implementing color display in a liquid crystal display, there has been widely used a color filter method in which white light is adapted to travel through color filters of three primary colors (red, green, and blue) provided for respective pixels, thereby conducting color display. In this color filter method, however, when light emitted from the light source travels through the color filter, only light having a specific wavelength is selected and transmitted, and light having the other wavelengths is absorbed. For this reason, light availability is low and power consumption is increased.
Accordingly, there has been proposed a field sequential color method for conducting color display by lighting a plurality of light sources adapted to emit different color lights by time division. In this field sequential color method, lights emitted from the respective light sources are directly used for image display without traveling through the color filters. This results in high light availability and reduced power consumption. In addition, cost is reduced because of absence of the color filters.
Since the liquid crystal display using the above color filter method implements color display using the color filters of three primary colors, it is necessary to conduct display for each set of three pixels, i.e., red, green, and blue pixels. On the other hand, since the liquid crystal display using the field sequential color method implements color display by lighting the respective color lights by time division, display is conducted for each pixel. So, to achieve an equal resolution on an equally-sized display panel, the size of pixels in the liquid crystal display using the field sequential color method is three times as large as the size of the pixels in the liquid crystal display using the color filter method.
However, if the pixels are thus large-sized, it is highly probable that substances mixed in a liquid crystal layer causes dot defects. The dot defects makes the image noticeably degraded because of the large-sized pixels.
In the liquid crystal display using the field sequential color method, one frame period of a video signal is comprised of a plurality of sub-frame periods, and it is necessary for liquid crystal to complete a response within each of the sub-frame periods. If the liquid crystal responds slowly, satisfactory image display is impossible to achieve. It is therefore desirable to use an OCB (Optically Self-Compensated Birefringence) mode liquid crystal capable of high-speed response.
In the liquid crystal display having the OCB-mode liquid crystal, by applying a relatively high voltage across a pixel electrode and a counter electrode, an alignment state of the liquid crystal is caused to transition from so-called splay alignment to bend alignment, and in this bend alignment state, an image is displayed. Hereinbelow, the transition from the splay alignment to the bend alignment is called splay to bend transition. With regard to the liquid crystal display having the OCB-mode liquid crystal, see “Syadanhojin Denki Tsushin Gattsukai Shingakugihou, EDI98–144, 199P.”
In the liquid crystal display having the OCB-mode liquid crystal, due to incomplete splay to bend transition, the liquid crystal partially remains in the splay alignment. In this case, the image is not normally displayed in pixels corresponding to the splay alignment liquid crystal, this would be observed as dot defects by an observer. As described above, since degradation of the image due to the dot defects is noticeable in the case of the large-sized pixels, it is required that the splay to bend transition take place more reliably.