Registers – Coded record sensors – Particular sensor structure
Patent
1995-11-03
1998-04-07
Hajec, Donald T.
Registers
Coded record sensors
Particular sensor structure
235462, 382189, G06K 710
Patent
active
057367230
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/GB 95/00572, filed Mar. 16, 1995.
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for identifying the orientation of a dot matrix code marking of an article.
BACKGROUND OF THE INVENTION
It is often required for components to be individually identified as they pass through a series of manufacturing stages so that a history of their manufacture is available for reference. One known method of identification is disclosed in our UK Patent No 2201808.
These components or workpieces are conveniently provided with a dot matrix identification marking and one dot matrix is read using an optical reader. The dot matrix code marking comprises a plurality of rows and columns on which dots comprising the code marking are located. The reader produces an output which is converted into a digital form by a processor. A further processor is provided to determine the orientation and position of the dot matrix code from the digitised image. The further processor worked by calculating the outer borders of the dot matrix code from the individual dots in the digitised image. This means that the edge of the dot matrix code has to have a reasonable number of dots along it, and each dot must be accurately located. However, not all dot matrix codes meet these requirements because the edges of some dot matrix codes have very few dots and in some cases the image processing performed to locate the dots is insufficient to locate all the dots. These two factors combine to cause the attempt to determine the orientation and position of the dot matrix code to fail in many instances.
SUMMARY OF THE INVENTION
The present invention seeks to provide a method and apparatus for identifying the orientation of a dot matrix marking of an article more easily.
Accordingly the present invention provides a method of identifying the orientation of a dot matrix code marking of an article relative to a datum, the dot matrix code marking having a plurality of rows and columns on which dots comprising the code marking are located, the method comprising image. fundamental inter dot spacing are located in the same row or column, datum, datum, article from the said angles.
Preferably producing the digitised image comprises viewing the dot matrix code.
Preferably producing the digitised image comprises illuminating the dot matrix code.
Preferably the digitised image of the dot matrix code is stored in a store, machining the component, and remarking the component in accordance with the digitised image of the dot matrix code in the store. Preferably the centre of each dot in the digitised image is located. Preferably a histogram of the distances between every dot located in the digitised image is produced and the fundamental inter dot spacing is determined from the histogram.
The present invention also provides an apparatus for identifying the orientation of a dot matrix code marking of an article relative to a datum, the dot matrix code marking having a plurality of rows and columns on which dots comprising the code marking are located, the image apparatus comprising means to produce a digitised of the dot matrix code, means to measure the distances between every dot located in the digitised image, means to determine the fundamental inter dot spacing, the dots separated by the fundamental inter dot spacing are located in the same row or column, means to determine the angle between the dots in one of the rows and the datum, means to determine the angle between the dots in one of the columns and the datum, means to determine the orientation of the dot matrix code marking of the article from the said angles.
Preferably the means to produce a digitised image comprises means to view the dot matrix code.
Preferably the means to produce a digitised image comprises means to illuminate the dot matrix code.
Preferably there is means to store the digitised image of the dot matrix code, means to machine the component, and means to remark the component in accordance with the
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Booth Christopher R.
Clarke Michael A. N.
Hajec Donald T.
Rolls-Polce plc
Tremblay Mark
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