| 摘要 |
<p>PURPOSE:To use a titled device even in a place where an amount of external light is abundant, by bringing a light emitting output of a light pen to an intensity modulation by an AC voltage, making an electric signal which is detected by a photodetector pass through a filter circuit passing through a frequency band of AC, and thereafter, recognizing it as a signal. CONSTITUTION:Many photoelectric cell groups are formed in a shape of a matrix on a substrate 1, and a matrix-shaped light input panel 1 is formed by fetching electrodes X1-Xn and Y1-Yn in the direction X and the direction Y, respectively, from each pole of the photoelectric cell. From this light input panel 1, the output is fetched by scanning an electrode through analog switches 2, 2' to X and Y, respectively, and thereafter, a signal output is fetched through a differential amplifier 3, a high-pass or band pass filter circuit 4, and an amplifier 5. On the other hand, a light input of a light emitting type light pen 6 is brought to an intensity modulation by an AC frequency passing through the filter circuit 4, and write is executed to a photoelectric cell Xiyj. In such a way, even in case external light exists, a signal can be read correctly.</p> |
