| 摘要 |
<p>A seed monitoring apparatus for use with a seed planting machine includes a seed sensor comprising a housing forming a substantially tubular passageway and mounting a light source and three photosensitive elements arranged substantially in a triangular configuration. The arrangement of the light source and the triangular photosensor configuration is such that a seed passing through the tubular passageway will momentarily obscure the passage of light to the photosensor the apex of the triangle, if at all, before obscuring the passage of light to either of the photosensors forming the base of the triangle. The monitoring circuit includes two signal paths in which different methods of counting are used to produce different numbers of pulses in response to signals from the three photosensors. One or the other of these signal paths is selected automatically in accordance with the rate at which seeds are detected. One of these signal paths includes a delay circuit interposed in the line from the apical sensor while the other includes a one shot circuit interposed in the line from the same apical sensor. Additionally, a bunch detector circuit produces a predetermined number of additional pulses or counts in response to seeds detected substantially simultaneously at the two sensors forming the base of the triangle.</p> |
