PURPOSE: To read the coordinates with high accuracy by providing a material that does not absorb the light emitted from a picture display device and absorbs the light of a light source to an optical guide path and irradiating a prescribed position on the picture display device with the light source to detect an optical input position.
CONSTITUTION: The light emission properties of a picture display device 2 are compared with the absorption factor properties of materials 8a and 14a which absorb the light of a light pen 4 and emits the light by themselves. As a result, it is known that no overlap is substantially detected excepting the beams of about 650W750nm wavelengths. Therefore it never occurs that the the material 14a absorbs the light emitted from a picture element 12 on the device 2 and emits the light by itself. While the material 8a absorbs the light of the pen 4 and emits the light by itself. The light of the material 8a is detected by a photodetector 10 and therefore the position of the input light of the pen 4 is detected. This attains a coordinate reading operation with high accuracy.
MAJIMA TOSHIAKI
KAN FUMITAKA
HAYAKAWA NAOJI
NOMURA ICHIRO
TAKENOUCHI MASANORI
SUZUKI HIDETOSHI
