U.S. Philips Corporation

Cornelis Johannes Schoot

Dirk J Gravesteijn

Jan Van Der Veen

Petrus J Kivits

Pieter Zalm

Gerardus Antonius Vermeulen

Marinus R De Bont

Hans Dignus Duinker

A method of manufacturing a homogeneous, water-insoluble dye layer on a substrate is provided in which a solution of a cationic or anionic dye in an organic solvent is provided on the substrate, the solvent is removed and the resulting dye layer is treated with an aqueous solution of a salt in which the cation of the anionic dye is exchanged for the cation of the salt or is treated with a salt or acid in which the anion of the cationic dye is exchanged for the anion of the salt or acid. The invention also provides a substrate provided with water insoluble homogeneous dye layer.

Method of manufacturing a water-insoluble dye layer on a substrate and

The invention provides an information-recording element in which information can be written and read optically. The element is constructed from a transparent substrate, a laser light-absorbing, dye-containing auxiliary layer provided thereon, as well as a laser light-reflecting recording layer present on the auxiliary layer. Upon recording information the element is exposed to pulsated laser light via the substrate, holes being formed in the recording layer. The auxiliary layer stimulates the formation of holes, a saving of laser light energy being obtained. In a favorable embodiment the auxiliary layer has a laser light absorption of from 20 to 80% and a maximum thickness of 2500 A. In a further favorable embodiment the auxiliary layer also comprises an endothermal material, for example, nitrocellulose having a nitrogen content of at least 11%.

Information-recording element having a dye-containing auxiliary layer

In the manufacture of screens for cathode-ray tubes, a substantial part of the screens being covered with a non-reflecting substance, hardened polyvinyl alcohol dots of relatively small diameter should be obtained by exposure via a mask with relatively large holes. Owing to an inadequate gradient of the photosensitive polyvinyl alcohol it is not possible to obtain dots of uniform size. The invention enables well-defined, uniform dots to be obtained by superposing a substance on the photosensitive layer which absorbs the light used during exposure, thereby decomposing into substances which do not or not substantially absorb this light. Thus, the effective gradient of the photosensitive polyvinyl alcohol is increased.

Method of making screens for cathode-ray tubes

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Eindhoven, Netherlands

Cornelis Johannes Schoot