Registers – Records – Particular code pattern
Patent
1991-06-18
1993-11-09
Pitts, Harold
Registers
Records
Particular code pattern
235464, 235466, G06K 1906
Patent
active
052605566
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to visual code reading systems, and more particularly to coded targets for such systems.
2. Description of the Prior Art
The utilisation of barcodes and their readers is now common practice both in industry and commerce for identification of articles and information relevant thereto. They function reliably where the environment is such as not to impede a clear vision of the barcode, but they are far less reliable where any obstruction occurs to a clear view by the reader. Furthermore, of necessity the code must be passed linearly with respect to the reader. They are invariably linearly constructed as generally barcode readers do not build an image of the coded area. Instead they search for at least one scan through the code which is completely error free. If such a scan does not exist then the code is indecipherable. This restriction, however, allows simple sequential line scanning techniques to be used and provides for cheaper readers. To cope with the possibility that no single scan can be error-free a memory system must be incorporated so that at least a partial image of the coded area can be constructed. If the reader is capable of being oriented appropriately with respect to the direction of the barcode lines then this can be achieved in a single line memory register. This technique has been applied in some proximity barcode readers. However, for non-proximity reading of a randomly oriented, randomly obscured code a full image must be acquired if the chance of reading the code is to be maximised.
There are many possible applications for visual code reading if reliable operation could be assured in an environment of random movement and/or partial obscurity of the target. One such application would relate to ear tags for animals, such as cattle and sheep. As a result of the large number of possible positions into which the ear tag can be placed by the animal, substantial complexity of conventional scanning and/or recording equipment would be needed to read data from the ear tag.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a coded target for visual reading which is of a reliable nature and can be provided at reasonable cost.
In accordance with the invention there is provided a coded target for providing coded data readable by an imaging apparatus, the target comprising location marking means for enabling location of the target by the imaging apparatus preparatory to an imaging operation, the location marking means having high visibility characteristics to enable identification of the location marking means against a background, the target further including at least one code marking region, each code marking region being of at least a segment of a generally annular shape, each code marking region including circumferentially disposed code markings containing coded data which are imaged by the imaging apparatus to enable recovery of the coded data from the target during or following the imaging operation.
The term "visible" and related terms such as "visibility", "optical", "imaging" and "light" do not necessarily refer only to light and visibility at wavelengths in the human visible spectrum. The invention is applicable to other wavelengths from in the order of 10.sup.-4 to 10.sup.-11 meters, such as infra red and x-ray radiation, and the terms used are to be understood as encompassing such other suitable electromagnetic radiation wavelengths.
The present invention has a basis in the realisation that once a full image has been acquired then computational procedures can treat a circular versus a linear barcode equally well. The prime considerations then become the need to maximise the data density and the need to make the data integrity independent of rotational aspect. In these latter considerations a circular format is preferred to a rectangular one.
Preferably the location marking means is located generally centrally of the code marking region(s) so that identification of the location marking means al
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Doerr Annegret
Kowald Errol M.
Lake Royden J.
Moore John C.
Australian Meat & Live-Stock Research & Development Corp.
Pitts Harold
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