1513306 Monitoring of seed dispensing DICKEY-JOHN CORP 18 July 1975 [14 Aug 1974] 30208/75 Heading AID [Also in Divisions G1 and G3] The rate at which seeds are fed from a dispenser to a plurality of planting drills is automatically controlled in response to first pulses from sensor 30 corresponding to individual seeds being sown, and second pulses from a sensor 21 corresponding to distance travelled by the drill, the second pulses being multiplied at 23 by a factor corresponding to the spacing between the rows, whereby the number of seeds planted per unit area is kept constant. The seed sensors 30 are not described, but there is one for each drill, their outputs being summed at 32. The distance sensor 21 is photo-electric (see Division G1, also Figs. 4..6, not shown). The seed and distance pulses are counted up and down respectively in a counter 29. If a "dead band" of counts is exceeded (because the seed pulses differ from the distance pulses more than a predetermined amount) a corrective motor 38 is driven to vary the transmission ratio between the seed dispenser and a road wheel 51 which drives it. The counter is associated with a second counter fed with pulses from a local oscillater: the arrangement is such that, if the error is small the motor is run for a short time, determined by the second counter, whereas if it is large the correcting motor runs continuously until the error is reduced. (Figs. 9, 10, not shown). Reference has been directed by the comptroller to Specification 1467966.
