Abstract A seed sensor detects seeds passing through a chute or housing forming a path of travel for seeds dispensed from a seed planter. A source of light such as a light emitting diode is optically exposed to the path of travel and a photosensitive element such as one or more photoresponsive transistors is optically exposed to the path of travel for receiving the light from the light source. An electronic circuit is connected with the photosensitive element for producing an electrical signal responsive to the light level incident thereupon and producing a change in the electrical signal in response to a momentary change in light level due to the passage of a seed. The electronic circuit includes a circuit element such as a diode connected with the photosensitive element for maintaining at least a given amount of change in the electrical signal output level in response to a given change of light level corresponding to passage of a seed. The circuit therefore is substantially unaffected by any change in the level of light transmitted from the light source or received by the photosensitive element not caused by passage of a seed, as for example due to the accumulation of dirt or dust partially obscuring either the light source or the photosensitive element.
In combination with a field seed planter having seed delivery conduit means associated with each row to be planted, seed sensor associated with each said conduit means comprising means forming a path of travel for the passage of seeds therethrough prior to said seed being planted, a source of light optically exposed to said path of travel and a light sensitive means optically exposed to said path of travel and to said light source for receiving light from said light source, and circuit means for effecting from said light sensitive means the emission of an electrical signal responsive to light incident thereon and a momentary change in said signal responsive to a momentary change in light level incident thereon due to passage of a seed between said light source and said light sensitive means, said circuit means including means coupled with said light sensitive means for maintaining a said momentary change in electrical signal substantially at a predetermined minimum value corresponding to said change in light level incident upon said light sensitive means, substantially regardless of any change of the level of light transmitted by said light source or received by said light sensitive means due to accumulation of dirt, dust or the like.
Claim 2
Dependent Claim
204 words
In combination with a field seed planter having seed delivery conduit means associated with each row to be planted, seed sensor associated with each said conduit means comprising means forming a path of travel for the passage of seeds therethrough prior to said seed being planted, a source of light optically exposed to said path of travel and a light sensitive means optically exposed to said path of travel and to said light source for receiving light from said light source, and circuit means for effecting from said light sensitive means the emission of an electrical signal responsive to light incident thereon and a momentary change in said signal responsive to a momentary change in light level incident thereon due to passage of a seed between said light source and said light sensitive means, said circuit means including means coupled with said light sensitive means for maintaining a said momentary change in electrical signal substantially at a predetermined minimum value corresponding to said change in light level incident upon said light sensitive means, substantially regardless of any change of the level of light transmitted by said light source or received by said light sensitive means due to accumulation of dirt, dust or the like.
Claim 3
Dependent Claim
16 words
A seed sensor according to claim 1 wherein said light source comprises a light emitting diode.
Claim 4
Dependent Claim
16 words
A seed sensor according to claim 2 wherein said light sensitive element comprises a photoresponsive transistor.
Claim 5
Dependent Claim
39 words
A seed sensor according to claim 3 wherein said last mentioned means in said circuit means comprises a diode having an anode electrode connected with an emitter electrode of said photoresponsive transistor and a cathode electrode connected with ground.
Claim 6
Dependent Claim
55 words
A seed sensor according to claim 1 wherein said light sensitive means comprises a plurality of photoresponsive transistors spaced across said path of travel and said last mentioned means comprises a plurality of diodes, each having an anode electrode joined to an emitter electrode of one of said photoresponsive transistors and a grounded cathode electrode.