Inspecting device for print
US4685139A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Mar 15, 1985 |
| Grant date | Aug 4, 1987 |
| Priority date | — |
| Expiry date | Mar 15, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/956
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention relates to an inspecting device for a print which can scan the entire print pattern of a printed sheet by an optical detecting device, detects the image information of the print pattern at every pixel, calculates the difference between the detected image information with reference information, delays the differential signal in several pixels in the scanning direction of the optical detecting device, calculates the difference between the differential signal and the delayed differential signal, sets a threshold level to the twice differential signal produced from the result, and judges the production of a printing defect when the twice differential signal exceeds the threshold level, thereby accurately detecting the printing defect even when the entire variation in the color density occurs on the printed sheet.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.