| 摘要 |
<p>To measure the range of shade sheltered from scanning light, a comparator compares the output from a photodetector element with a threshold established by an MPU. The range where the former is smaller than the latter is measured to be a shadow. During a cycle of optical scanning, the threshold is varied in two or more steps depending on the scanning angle. The position and size of a pointing object such as a finger or pen are determined by measuring the shade sheltered from the scanning light.</p> |
