| 摘要 |
<p>PURPOSE: To converge light with fixed illuminance by placing a detector at a position where fixed luminance is obtd. with respect to light obtained by being reflected at the position and opening existing over an irradiated depth to be diverged. CONSTITUTION: An optical device for forming parallel light beams is provided with three flat projecting lenses, typically with the magnification of about twenty times. An opening part, namely a stop member 90, forms parallel beams along a main axis, namely a vertical axis. A telescope type optical device part 48 is provided with a lens 50 to form the focal point of the beams near the lens 52. Then a trigger switch 90 turns on a diode 42 to turn on a tracking beam lamp 56. In this case, a condenser lens 32 in front of a detector and an opening stopping member 92 provides fixed illuminance over all the area of the focal point depth of a scanner in front of a port and the detector generates a fixed output signal. This signal is deciphered to provide equivalent display on a display board.</p> |
