Sanyo Electric Co., Ltd.

Kazunori Kodama

Toshiyuki Watanabe

Naoki Kaise

Takeshi Fujisaki

Hirohisa Kitagishi

A image distortion correction unit which corrects a distortion of a projected image includes: a switching unit which operates in response to an operation signal from a Keystone remote controller button to switch correction by a trapezoidal distortion correction process and correction by a corner distortion correction process back and forth; a determination unit which determines whether any one of the correction by the trapezoidal distortion correction process and the correction by the corner distortion correction process has been performed; and a prohibition unit which prohibits switching the trapezoidal distortion correction process and the corner distortion correction process back and forth if the determination unit determines that any one of the correction by the trapezoidal distortion correction process and the correction by the corner distortion correction process has been performed and the operation signal is also received from the Keystone remote controller button.

Excellently operable projection image display apparatus

A liquid crystal display apparatus includes first and second PLL circuits, a memory, and a liquid crystal panel. Dot data or line data of a video signal is written into the memory in response to a write clock signal from the first PLL circuit. Data are read from the memory in response to a read clock signal from the second PLL circuit. A read reset signal for reading dummy data is also supplied from the second PLL circuit to the memory. If the number of dot data the video signal has in one horizontal period is smaller than the number of horizontally arranged pixels of the liquid crystal panel, dummy data is read in response to the read reset signal after all the dot data in that one horizontal period have been read. On the other hand, if the number of line data in one vertical period is smaller than the number of vertically arranged pixels of the liquid crystal panel, dummy data is read in response to the read reset signal after all the line data in that one vertical period have been read. As a result, an optimal picture can be displayed on the liquid crystal panel.

Growing community of inventors

Osaka, Japan

Kazunori Kodama