Doing Your Own Provisional Patent Application and Filing Online

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When a spear is illuminated by the bottom laser the appropriate lens and photo detector provide the electronic control circuitry with the location across the bed so the correct blade will be fired.  But unless the upper beam is also broken the spear is not long enough to harvest and thus will be ignored. If the channel directly above the activated lower channel or the channel above and on either side is also detected, then the system knows the spear is long enough to cut and it then fires the appropriate blade to cut the spear.

The lower beam provides the location information, and is obtained much closer to the ground than other harvesters which obtain the location of the spear at the cutting height. When a spear is straight and does not lean in any direction, the height off of the bed at which the horizontal location is obtained does not mater, but if a spear is leaning or curved then the horizontal location information is more accurate as you get closer to ground level.  Since this machine is the only machine that obtains the location information closer to the bed than the cutting height it is the most accurate.

Nothing on the machine over the bed extends down to the cutting height, so there is nothing to break spears as the machine moves along the bed. It is a totally non-contact system. With beam breaking methods there must be a support structure to hold the optical components on either side of a channel, which would necessarily be slightly closer to the ground than the minimum cutting height. 

The laser beams are typically very small in diameter and thus provide high accuracy.  The laser beams are less than 1/10 of an inch in diameter.  This provides very precise location information.  The lasers are pulsed at around 40,000 times a second. Any one pulse is enough to trigger the sensor. 

Occasionally two or more spears will be lined up across the bed in such a way that one spear might block the beam causing any other spears lined up with it to be in shadow and not get illuminated by the laser.  Therefore I put a laser on each side of the bed and lined them up so the two beams are facing each other and concentric.  There is less chance of missing a spear that way.

For even more accurate information about where the spear is entering the ground, more than two beams could be used across the bed, and a computer algorithm could plot the spear and anticipate where it enters the soil.  Taken to the extreme, a video camera could be used as the detectors which would allow extremely accurate prediction of the correct blade to fire.

Another consideration is when the spears lean in the direction the machine is traveling or in the opposite direction of machine travel. With the previous system (prior art), the spears could not lean much in the forward or rearward direction because they needed to cross both beams at the same time. 

A new improvement to the system would be to provide a pulse of a longer duration than the time required for the machine to move past the spear.  For example, if the machine was moving forward at 20 inches per second, slightly more than 1 mph, then in one tenth of a second it would travel 2 inches. 

A spear leaning in the direction of travel will encounter the upper beam before it encounters the lower beam.  Normally, as with a beam breaking or similar method of detection, a spear leaning forward would cause the machine to think the spear was further ahead of where it really enters the ground.  Thusly the machine would cut "late" and sever the spear well above the ground.

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