Arrangement for scanning printing plates

US4586148A · kind A · utility

Assignee

• MAN Roland Druckmaschinen AG · DE

Inventors

• Jurgen Rehder · Bexbach, DE
• Siegfried Schuhmann
• Gerd Steiner · Heusenstamm, DE

Key dates

• Filing date: Jun 3, 1983
• Grant date: Apr 29, 1986
• Expiry date: Jun 3, 2003

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S101/46
• WIPO field: Textile and paper machines
• WIPO sector: Mechanical engineering

Abstract

A machine for scanning printing plates to determine the ratio of "printing" to "non-printing" area for pre-adjustment of the ink dosing elements of a printing machine has an array of electronic photo-sensors, each sensor being disposed in a channel having low-reflection chambers which permit sharp delimination of resolution elements on the printing plate and ensure high definition scanning of different types of printing plates under practical conditions. Preferably the diaphragms dividing the channel into chambers have greater spacing at greater distances from the element sensed on the printing plate. To accommodate printing plates of different materials, means are provided for selecting the wave length of the light source. To prevent measurement error due to changes in the distance from the printing plate to the light source and sensor array, the photosensor array is preferably directed or aimed 60.degree. to 45.degree. with respect to the normal vector of the printing plate, and the light source is in the same quadrant as the photo-sensor array at an angle of 0.degree. to 45.degree. with respect to the normal vector. Automatic calibration, automatic printing plate size determinat…