| 摘要 |
<p>An optical mark detector comprises a light source (2) comprising a transverse array of LEDs (3). The LEDs may be illuminated individually to illuminate a particular portion of a form (4) to be scanned, the width and position of the portion being determined by a mask (5) interposed between the light source (2) and an optical fibre array (6) which transmits light from the mask to the item to be scanned. The presence or absence of a mark within the illuminated portion is determined by a sensor (7) comprising a linear array of optical fibres (9) extending across the full width of the detector, coupled to a single transducer (8). The presence or absence of a mark at a particular position will be determined by the output of the transducer (8) when the particular position is illuminated by the LED known to correspond to that position.</p> |
