POINTING POSITION DETECTOR, IMAGE DISPLAY DEVICE, PRESENTATION SYSTEM AND INFORMATION STORAGE MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a presentation system capable of exactly and automatically detecting a pointing position on an image indicated by using a pointing means. SOLUTION: This presentation system comprises a plurality of position reference parts 30-1, 30-2 and 30-3 provided on a screen 20 for transmitting/receiving ultrasonic signals to/from a pointing stick 40 and a digitizer 50 for detecting the pointing position on the image on the basis of distances among the position reference parts and the receiving time difference of the ultrasonic signals. Each of the position reference parts 30 is provided with a means for receiving the ultrasonic signal for distance measurement from the other position reference part. The digitizer 50 transmits/receives the ultrasonic signals for distance measurement to/from the plurality of position reference parts and measures the distance among the position reference parts on the basis of transmitting/ receiving time thereof.