Abstract: A thin film transistor is designed in such a manner that a semiconductor region includes source and drain electrodes in a channel width direction and further, a planar source-side overlap area constructed by a gate electrode, the source electrode and the semiconductor region and a planar drain-side overlap area constructed by the gate electrode, the drain electrode and the semiconductor region exist. An optimal overlap length of one of the source-side and drain-side overlap areas in a channel length direction is determined, for instance, to be 4 &mgr;m, for a light incident on a channel portion of the thin film transistor to have a light intensity below or equal to 0.2% of a light intensity of the backlight incident toward the thin film transistor, thereby reducing a light-induced OFF leak current sufficiently and further improving flickering and display uniformity.

Abstract: In a TFT (Thin Film Transistor) of the present invention applicable to an LCD (Liquid Crystal Display) includes a gate electrode, a gate insulation film, an island-like semiconductor layer, a drain electrode and a source electrode sequentially laminated on a transparent insulative substrate. A part of the semiconductor layer above the gate electrode in the direction of channel length has a smaller dimension than the other part in the direction of channel width. With this configuration, the TFT reduces a light OFF current while preventing a light ON current from being reduced.

Abstract: A thin film transistor is designed in such a manner that a semiconductor region includes source and drain electrodes in a channel width direction and further, a planar source-side overlap area constructed by a gate electrode, the source electrode and the semiconductor region and a planar drain-side overlap area constructed by the gate electrode, the drain electrode and the semiconductor region exist. An optimal overlap length of one of the source-side and drain-side overlap areas in a channel length direction is determined, for instance, to be 4 &mgr;m, for a light incident on a channel portion of the thin film transistor to have a light intensity below or equal to 0.2% of a light intensity of the backlight incident toward the thin film transistor, thereby reducing a light-induced OFF leak current sufficiently and further improving flickering and display uniformity.

Abstract: An active matrix-type liquid crystal display device driven by a transverse electric field is provided which is capable of providing a superior image quality without showing after images or uneven images by maintaining the potential of the black matrix at an optimum value, while maintaining the black matrix in a floating state; the active matrix-type liquid crystal display device being constructed by a pair of transparent insulating substrates, and on the TFT substrate, a plurality of scanning lines and a plurality of signal lines, thin film transistors formed near the crossover points of the scanning and signal lines, pixel electrodes connected to the TFTs, and counter electrodes formed facing to the pixel electrodes are formed with a transverse electric field being generated by applying a voltage between the pixel electrodes and the counter electrodes, and a slit with a predetermined size being formed in the black matrix formed on the other CF substrate.