Showing papers on "Watermark published in 1989"

Sensor for verification of genuineness of security paper

Abstract: A method and a device for automatic verification of genuineness of a banknote or a document comprising a watermark is described. A two-part, doubly active capacitive sensor device (4, 6, 7) is used. A symmetry property of the sensor output signal is changed in a predetermined manner when a correct watermark is present in a coinciding position with shape adapted capacitor electrodes (4, 6).

Artificial watermark paper prodn. - by printing paper with engraved plate with watermark in high pressure process with crosslinked polyether and isocyanate

Abstract: Paper is given an artificial watermark by printing the paper with an engraved plate with the desired watermark in a high pressure process with a raw material mixt. of 20-75 wt.% of a crosslinked polyether contg. OH gps, 20-75 wt.% hydroabiethyl alcohol. ADVANTAGE - The watermark is simple to apply and not detectable without holding the paper up to the light.

A lazy buddy system bounded by two coalescing delays

Abstract: The watermark-based lazy buddy system for dynamic memory management uses lazy coalescing rules controlled by watermark parameters to achieve low operational costs The correctness of the watermark-