Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1992-02-11
1994-07-19
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
250560, 356379, G01V 904
Patent
active
053311485
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The current invention comprises a method and a device for the recording of the number and size classification of objects, particularly live fish.
PRIOR ART
Intensive production of fish (breeding of fish) is a rapidly growing trade. It is anticipated that its importance still will grow strongly in extent. In connection with the intensive production of fish, the recording of number of fish and the size classification of fish are frequently required.
Sale of live fish is usually done on the basis of number and, as a sale may comprise several hundreds of thousands, the execution of a rapid and accurate recording of fish number becomes of great importance. In order to achieve the largest possible growth, it is important regularly to carry out size classification of the fish such that the size variation in the different storage vessels is kept at a limited amount. The individual fishes grow with varying speed, and larger fish restrict the growth of smaller fish kept in the same vessel.
There are several methods for the counting and size classification of live fish. Usually, the counting of fish is performed manually. However, several devices for the automatic recording of number have emerged recently. These automatic counting devices are characterized in that they require a distance between adjacent objects, in order to achieve an accurate recording of number. This requirement restricts the capacity of the devices substantially. For the size classification of live fish, a series of different methods are used, e.g. using rotary rollers having an uniformly ascending slot, or using several gratings having varying slot widths. Common to these methods is that the size classification occurs on the basis of the thickness of the fish. A number of fish species, such as e.g. turbot, halibut and other flounders, exhibit great variations in the proportion between thickness and size/weight.
Both when recording the fish number and when classifying fish by size, the fish have to be treated as non-injuriously as possible.
DESCRIPTION OF THE INVENTION
The object of the current invention is to provide a method and a device of the kind mentioned above, which is accurate, non-injurious to the fish, a minimum time of residence in air, and which has a high capacity.
The single FIGURE of the drawing shows one embodiment of the device and method of the present invention.
According to the invention, its objects are achieved through measuring the area of the fish when they are falling freely. Each fish falls between a light source (1) and a CCD-line camera (2) associated with an objective lens (3), and the fish will then form a shadow area which is conceived by the CCD-camera. A signal processing card (4) records and stores data conceived by the CCD-line camera. These recorded data are further read by a computing-card (5) which executes calculations. The area recorded is influenced both through the size of the object and its speed at the time of recording. In order that objects having the same size shall be recorded with the same shadow area, it is necessary that the objects have the same speed. According to the invention, this is achieved in that the objects fall freely from a certain height. In case several objects pass the lens simultaneously, e.g. laterally of each other, the computer-card will calculate the number of objects on the basis of a recorded mean value of single objects. In contrast with other known principles of counting, this principle does not require a distance between adjacent objects.
Prior to using the device for counting, the user decides a probable mean value through executing test measurements of individual objects or through the use of stored and already known values, and what permissible variation on either side of this value that is to be estimated as individual objects. This tolerance is determined on the basis of the existing variation by size for objects to be recorded. If the objects have the same size, then the tolerance is determined to be approximately equal to zero. In connection
REFERENCES:
patent: 3040980 (1962-06-01), Mann et al.
patent: 4012622 (1977-03-01), Boys
patent: 4628520 (1986-12-01), Menger
patent: 5142160 (1992-08-01), Storbeck
Le Que T.
Nelms David C.
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