Browse Prior Art Database

Verification of Print Quality in Man-Printed Items

IP.com Disclosure Number: IPCOM000047332D
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Ahtik, I: AUTHOR [+3]

Abstract

In this print-quality inspection circuit, a light 1 illuminates the printing on a passing work item and an image is formed by lens 3 on video camera 4. The raw video signal 5 is corrected by a shading corrector 6, resulting in a corrected video signal 7 which comprises the light-to-dark transitions that correspond to the presence of the lettering on sample 2. This video signal 7 is digitized by threshold detector 8. A built-in hysteresis insures stable detection. The pulses in digital signal 9 are counted by a counter 10; the resultant count appearing on lines 11 is read by microprocessor 12 after each horizontal scan line. Microprocessor 12 is synchronized to the scan rate of camera 4 with horizontal/vertical sync line 13. The flow chart shown in Fig. 2 shows the steps in processing the master text.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 75% of the total text.

Page 1 of 2

Verification of Print Quality in Man-Printed Items

In this print-quality inspection circuit, a light 1 illuminates the printing on a passing work item and an image is formed by lens 3 on video camera 4. The raw video signal 5 is corrected by a shading corrector 6, resulting in a corrected video signal 7 which comprises the light-to-dark transitions that correspond to the presence of the lettering on sample 2. This video signal 7 is digitized by threshold detector 8. A built-in hysteresis insures stable detection. The pulses in digital signal 9 are counted by a counter 10; the resultant count appearing on lines 11 is read by microprocessor 12 after each horizontal scan line. Microprocessor 12 is synchronized to the scan rate of camera 4 with horizontal/vertical sync line 13. The flow chart shown in Fig. 2 shows the steps in processing the master text. The flow chart shown in Fig. 3 illustrates the steps in checking production printing. Several features can be added to mask out noise (ink splatters, vibrations of the camera fixture, background irregularities) and minimize the effect of text misregistration, for example: - Scan the text several times and compute the average number of transitions for each field. - When defining fields from master text, ignore any information that appears on less than a minimum

number of lines. - Compute DELTA for each field to be proportional to the amount of text present, so that the allowed

bracket always corresponds to about one l...