| Seed-counting machine | |
|---|---|
 A seed counter and packager | |
| Industry | Agriculture |
| Application | Counting seeds |
Seed counting machines countseeds for research andpackaging purposes. The machines typically provide total counts of seeds or batch sizes for packaging.
The first seed counters were developed to countlegumes and other seeds which were large.[1]
Traditionally, the seedpackaging industry packed seeds by weight but sold them by number. In order to assure the correct quantity of seeds, the distributors added a safety margin to the packed weight, like abakers' dozen. This safety margin increased cost. By counting the seeds, the margin of error could be reduced and so costs reduced.[2]
Originally people counted seeds by hand, or used a trip board. The first seed-counting machine was thevibratory mechanical seed counter. Modern day electronic seed counters are faster and more accurate.[3]
In 1929 theUS Bureau of Plant Industry worked with several seed companies to perfect a seed counter.[4] In 1962 an electric seed counter was developed by the USDA'sAgricultural Marketing Service. The electronic counter operation involved the a vibrating the seeds so that they move to the edge of the counting machine.[1]
The machine will pay for itself over thelabor intensive tedious task of manually counting seeds, which is necessarily characterized byhuman error. By contrast, the new devices, even in the early 1960s, boasted increased speed and “about 1 error in counting 10,000 seeds counted.” The accuracy helps lessen the need to build in safety margins forquantity; and the costs of the machinery can be more than paid for by reducedlabor costs.[2]
In the 1970s other electronic seed counting advancements included anelectric eye to count the seeds. Seed counting still involved vibrating the seed, but now the seed would fall through a seed hole.[5]
If the items are put onto the conveyor in a single file, then a simple counting mechanism may provide satisfactory results. However, such a mechanism is inherently slower than if the items were freely placed on the conveyor without posing such limitations. Thus, in the 2000s other parallel counting of multiple objects evolved, including devices that use multiple electromagnetic energy sources and receptors.[6]
At one time, the methodology included use ofvacuum tubes,vacuum pumps, alight source and aphoto transistor. The size needed to be adjusted so only one seed passes through at a time. To be useful,batch counters need to be commercially available. A single presetcount facility is a plus, as is “adequate count capacity, the ability to provide external power supplies and [control of] ... the means to stop the picking up and counting of seeds.”[7]
In commercial operations, it is important for the counter to be automatic and accurate. For example, one commercial counter is capable of measuring the hundredth/thousandthgrain weight forseeds,tablets,pearls, and small components. It adoptsfar-infrared area sensor, and a large enoughphotosensitive area, "suitable for the sensitivity of all crops (millet-peanut)." Blockages orsplashes are to be avoided. Adaptable speed variation adjustment helps "solve the contradiction between speed and accuracy, and ensure error-free counting (counting error of 0/1000)" Manual feeding vs automatic cup changing "improve the counting efficiency, reduce labor intensity." Automatic discharge can obviate demands for the operator to constantly feed the vibrating plate. One counter is so fast thatMillet "counting can reach 2000 grains/min, and thewheat andrice counting" Suitability of the vibrating plate for different seeds is a consideration. It is useful to have an adjustable baffle at the exit of the bowl "according to the diameter of the seeds (workpieces), only one seed (workpiece) at a time, not side by side, for all large and small seeds."[8]
Some seed counters uselaser light.[9]
In counting, it is important to position one seed at a time by manipulating slitwidth when using aPhotoelectric seed counter.[10]
Some are able to handle up to 23 sample containers. They can do this while maintaining notable accuracy.[A] General purpose electronic seed counters usually count seeds duringfree fall. They have achieved satisfactory error rates.[9] For example: "Counting errors of less than 0.4% at counting speeds of 400 to 1,180 seeds/min were obtained for seeds of nine different species ranging in size from corn (Zea mays L.) to trefoil (Lotus corniculatus L.). Under some conditions, the seed dispenser, a vibratory small parts feeder, segregated wheat kernels (Triticum aestivum L.) into weight classes dispensing heavier kernels first into the counting system."[11][12]
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