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Manufacturing Error Coding Scheme

IP.com Disclosure Number: IPCOM000038929D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Johnson, M: AUTHOR

Abstract

Using information from manufacturing testing, off-specification parameters are encoded and printed upon the manufactured item, such as a dot printer band. In use, the tolerance data is read and the operation is electronically corrected to compensate for the off-specification parameters identified. Many mechanical parts must be produced to very high accuracy for suitable machine performance. This accuracy reduces process yield and increases cost. A typical example is the print band used in dot-matrix printers. The print band 1 comprises a number of printing dots 2, etched timing structure 3 telling when the print-hammers should be fired, and off-specification tolerance data 4. Tolerances in manufacturing cause errors in dot placement, and in timing grid accuracy, adversely affecting print quality.

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Manufacturing Error Coding Scheme

Using information from manufacturing testing, off-specification parameters are encoded and printed upon the manufactured item, such as a dot printer band. In use, the tolerance data is read and the operation is electronically corrected to compensate for the off-specification parameters identified. Many mechanical parts must be produced to very high accuracy for suitable machine performance. This accuracy reduces process yield and increases cost. A typical example is the print band used in dot-matrix printers. The print band 1 comprises a number of printing dots 2, etched timing structure 3 telling when the print-hammers should be fired, and off-specification tolerance data 4. Tolerances in manufacturing cause errors in dot placement, and in timing grid accuracy, adversely affecting print quality. The tolerance data is coded and printed on the printband. This states the dimensional errors of each dot with respect to its nominal timing position. For example, if the possible placement error of dots is +/- 0.015", and an ultimate precision of 0.0005" is desired, then 5 bits of information suffice. This can be coded in optically read bar-codes on the band itself, which has ample area available. In fact, much more information can be encoded on the band, such as manufacturing history, print dot size and spacing, band temperature coefficient of expansion, etc. This information may be used once to set up the machine, or it may be read rep...