U.S. Philips Corporation

Michael Bredol

Jacqueline Merikhi

Dieter Wadow

Cornelis Reinder Ronda

Ulrich H Kynast

Joachim F Opitz

Friederike Picht

Frans H Vollebregt

Thomas Rink

Irmgard Kohler

Guido Hutten

A phosphor composition of a sulphide-containing phosphor with a coating comprising a hydroxycarboxylic acid can be stored as a dry substance in the desagglomerated state and can be readily resuspended.

Phosphor composition with a hydroxycarboxylic-acid coating

A method of manufacturing a phosphor composition of a phosphor comprising a pigment coating of hematite, includes a first step in which the phosphor is coated with an iron-containing starting compound for hematite, and a second step, in which the phosphor with the coating is calcined, thereby converting the iron-containing starting compound for hematite into hematite. The calcining operation is carried out in an atmosphere of a gas mixture of water vapor and an oxidizing gas.

Manufacture of a phosphor composition with hematite

The invention relates to a display screen having a phosphor layer of a phosphor composition of a phosphor coated with an oxygen compound of one of the elements magnesium, calcium, barium, zinc and aluminium, and with colloidal SiO.sub.2 having an average particle size of 70 nm.ltoreq.d.ltoreq.130 nm. The invention further relates to a phosphor composition of a phosphor coated with an oxygen compound of one of the elements magnesium, calcium, barium, zinc and aluminium, and with colloidal SiO.sub.2 having an average particle size of 70.ltoreq.d.ltoreq.130 nm, and to a method of manufacturing the phosphor composition.

Phosphor composition with a coating of colloidal SiO.sub.2 particles and

A color display screen having a coating which comprises at least a greend an/or a red phosphor as well as at least a pigment having the following composition:

Color display screen comprising a contrast-enhancing pigment

A color display screen comprising a coating which contains at least a green and/or a red phosphor and at least a pigment having the composition Zn.sub.3-3x In.sub.2xy Ga.sub.2x-2xy S.sub.3, wherein 0.2&lt;x&lt;0.97 and 0.1&lt;y.ltoreq.1.0, yields a high-contrast and low-reflection picture, because the solid-solution properties of the pigmentation in accordance with the invention enable its absorption properties to be accurately adapted to the emission spectrum of the phosphor. The solid solutions having the above-mentioned composition are characterized by steep absorption edges in the yellow-orange spectral range and by a high absorptivity. This permits thin pigment-containing layers and small quantities of pigment to be used.

The invention relates to a luminescent zinc sulphide of cubic structure (sphalerite) which is so activated by aluminum and copper that a green-emitting luminescent material is created. In a simple manufacturing process, high x-values of the colour point and high luminous efficacy values are achieved in that copper is added in a quantity of 200 to 450 mole ppm and aluminum in a quantity of 700 to 2000 mole ppm.

Green-luminescing zinc sulphide and cathode ray tube provided with this

The invention relates to a method of manufacturing ZnS particles by wet-chemical precipitation from aqueous zinc salt solutions, ZnS being precipitated onto nuclei introduced into the solution. Nuclei of a controlled particle size and particle size distribution are obtained in that the nuclei of the aqueous precipitation solution are added in the form of a water-soluble organosol which contains the nuclei.

Method of manufacturing ZnS particles

The invention relates to a method of coating red-luminescing phosphor particles with hematite (.alpha.--Fe.sub.2 O.sub.3), whereby first Fe(OH).sub.3 is deposited on the phosphor particles and subsequently converted into .alpha.--Fe.sub.2 O.sub.3 at a raised temperature. A good adhesion of the hematite pigments to the phosphor particles is achieved in that first an aqueous solution of an iron(III) salt and a complexing agent is prepared, in which the complexing agent and its concentration are so chosen that in combination with Fe.sup.3+ ions complex ions are formed which on the one hand do not yet precipitate at a pH-value which is at least 0.5 higher than the value at which the phosphor particles just fail to be chemically attacked anymore, and which are dissociable at a further increase in the pH-value so that Fe(OH).sub.3 is formed, in that subsequently, if the pH-value is not yet high enough, a basic substance is added to the mixture, in that the pH-value is increased to a value which is at least 0.5 below the value at which Fe(OH).sub.3 starts to precipitate and at least 0.5 higher than the value at which the phosphor particles just fail to be chemically attacked anymore, in that subsequently the phosphor particles are added while stirring, in that at any moment, as required, a substance is added which dissociates upon an increase in temperature and which behaves as a base upon dissociation, and in that then the temperature of the suspension is slowly increased, whereby the phosphor particles are coated with Fe(OH).sub.3 through homogeneous precipitation.

Growing community of inventors

Aachen, Germany

Michael Bredol