| 摘要 |
PROBLEM TO BE SOLVED: To allow a user to use a light pen at an appropriate, not too far, distance and angle with respect to an image display screen, and to enable quick response in the event of a trouble.SOLUTION: A light pen 50 includes; a photosensitive element 52 which generates a photoreception signal by receiving light emitted by an image display device 30 being driven in accordance with a field period comprising a plurality of sub-fields including a y-coordinate detection sub-field for emitting light to detect a y-coordinate on an image display screen and an x-coordinate detection sub-field for emitting light to detect an x-coordinate on the image display screen; a coordinate computation unit 56 which computes coordinates of a location being pointed on the image display screen on the basis of the photoreception signal; and a photoreception state display unit 57 which shows whether or not the light pen is in a first photoreception state, in which the emission in the y-coordinate detection sub-field and the emission in the x-coordinate detection sub-field being received have light intensities equal to ot more than a predetermined threshold. |
