U.S. Philips Corporation

Peter E Geittner

Hans-Jurgen Lydtin

Peter K Bachmann

Howard J Wilson

Hans-Jurgen E Hagemann

Georg Friedrich Gartner

Dieter Leers

Jacques P Warnier

Ernst Klein

Gerd Romanowski

Georg G&auml;rtner

Cornelis P Auwerda

Petrus W Linders

Alfred L Weling

An electric discharge tube or discharge lamp comprising a scandate dispenser cathode which is composed of a cathode body and a coating having an emissive surface, said cathode body including a matrix of at least one refractory metal and/or a refractory alloy and a barium compound which is in contact with the matrix material to supply barium to the emissive surface by means of a chemical reaction with said matrix material, and the coating containing one or more multilayers which may include a bottom layer of tungsten and/or a tungsten alloy, an intermediate layer of rhenium and/or a rhenium alloy and a top layer of scandium oxide, a mixture of scandium oxide and rare-earth metal oxides, a scandate and/or a scandium alloy, is characterized by a long service life and a high emission-current density.

Electric discharge tube or discharge lamp and scandate dispenser cathode

An electric discharge tube or discharge lamp, in particular a flat-panel display screen, includes one or more low-temperature cathodes having a holder, which, optionally, is provided with a heating or cooling element, a conductive bottom layer which is applied to the holder, optionally a substrate with dispenser material, and a top coating of ultrafine particles having a nanostructure. The top coating has a surface layer consisting of an emitter complex formed from an emission material comprising several components. The cathodes have a high reliability and a long service life under a normal working load. The emission is stable, which contributes to a constant picture quality throughout the life of the discharge lamp or discharge tube. The discharge tubes or discharge lamps in accordance with the invention have short switching times and the advantage that their construction has been simplified and that their energy consumption is low. A method of manufacturing low-temperature cathodes in accordance with the invention is described.

Low-temperature cathode having an emissive nanostructure

An X-ray examination apparatus includes an X-ray filter with a plurality of filter elements for locally attenuating the X-ray beam. The X-ray absorptivity of each filter element is controlled by the amount of X-ray absorbing liquid with which the filter element is filled. The filling of filter elements is controlled by a voltage. The X-ray absorbing liquid contains a suspension of very small X-ray absorbing particles.

X-ray examination apparatus with x-ray filter

In the PCVD method glass is deposited in layers on the inner wall of a glass tube by heating the tube to a temperature between 1100.degree. and 1300.degree. C., by passing a reactive gas mixture through the glass tube from a gas inlet side at a pressure between 1 and 30 hPa, by forming a plasma in the interior of the glass tube, and by reciprocating the plasma between two reversal points. After a quantity of glass corresponding to the desired fiber optical construction has been deposited, the tube is collapsed to form a solid preform from which optical fiber are draw. The range of nonconstant deposition geometry at the preform entrance, (i.e. on the gas inlet side), is reduced by interrupting the reciprocating movement of the plasma at the reversal point on the gas inlet side.

Method of manufacturing optical fibres

In the manufacture of preforms for optical fibres, the materials of the core (.alpha.) and of the light-conducting cladding layer (.beta..sub.1) are previously deposited from the gaseous phase. Deposition time is here considerably reduced in that only the materials of the core (.alpha.) and a part of the light-conducting cladding layer (.beta..sub.1) are deposited from the gaseous phase and the remaining light-conducting cladding material (.beta..sub.2 +.beta..sub.3) is supplied as pre-formed tubes of cladding material.

Method of manufacturing a monomode optical fiber

A substrate (35) is coated by using starting materials which are supplied in the form of clusters (28). The clusters are disintegrated into their molecular or atomic constituents, and the constituents are deposited on the substrate in the form of compact layers (34). In this manner it is attained that the layers have a defined structure and do not exhibit inclusions in the form of foreign molecules.

Method of manufacturing solid bodies

Method of and arrangement for manufacturing rotationally symmetrical porous solid bodies. A method of manufacturing rotationally symmetrical porous solid bodies, in which the starting material for the solid body in the form of a suspension consisting of the material for the solid body in solid form and a liquid dispersing agent, is introduced into a hollow mould whose geometry corresponds to that of the solid body to be formed, such that during the introduction of the suspension the hollow mould is rotated about its longitudinal axis, a certain quantity of solid of the suspension being deposited on the inner wall of the hollow mould, and excess residual suspension being removed, after which the green body thus formed is subjected to further process steps to manufacture the solid body, in which process suspension is introduced into the hollow mould in such doses that each time only thin solid layers having a thickness in the range from 10.sup.-3 to 5 mm are continuously deposited without interruption of the centrifuging process, the excess residual suspension being removed from the hollow mould in such a quantity that a layer of residual suspension having a thickness in the range from 10.sup.-1 to 100 mm always remains on top of the deposited solid matter. In this way, macroscopically homogeneously built porous solid bodies are obtained. FIG. 2.

Method for manufacturing rotationally symmetrical porous solid bodies

Optical fibres whose refractive index profiles show specific peripheral and/or radial and/or axial optical modulation structures are manufactured according to the PCVD method, in which such method parameters are varied which influence:

Method of manufacturing optical fibers

In an optical fiber based on silicon dioxide with fluorine doping which determines its refractive index profile, at least in the light transmitting core a substance is added that increases the thermal expansion coefficient. The added substance is uniformly distributed at least in the light transmitting core, and reduces the influence of the drawing force F.sub.Z (during drawing of the preform) on the Rayleigh scattering .alpha..sub.R and the wavelength-independent 'c term' losses. Even at high fluorine dopant concentrations, low Rayleigh scattering losses in the range of the material-intrinsic losses pure for silicon dioxide are achieved. The OH-contamination level is also further reduced, and cracks in the collapsed preforms are largely avoided.

Fluorine-doped optical fibre and method of manufacturing such fibre

In the PCVD method glass layers are deposited on the inner wall of a glass tube by heating the tube to a temperature between 1100.degree. and 1300.degree. C., passing a reactive gas mixture at a pressure between 1 and 30 hPa through the glass tube, and moving back and forth inside the glass tube a plasma. After the glass layers are deposited, the glass tube is collapsed to produce a solid preform from which optical fibers are drawn. The regions of nonconstant deposition geometry at the ends of the preform (taper) are reduced by moving the plasma in the area of at least one reversal point nonlinearly with time and/or by changing the longitudinal extent of the plasma as a function of time. The length of the ramp is chosen to ensure an effective reduction of the end taper.

Method of fabricating optical fibers

The inside of a tube of an electrically insulating material is coated with a layer of electrically insulating material by reactive deposition of the coating material from a gas mixture which is passed through the tube. The tube is heated and the deposition is activated by a plasma produced by microwaves. The plasma reciprocates in the tube. Energy consumption is reduced by heating the tube to the reaction temperature at least partly by the energy supplied by the plasma to the tube wall. Thermal losses of the tube are reflected back to the tube wall by a heat reflecting element.

Growing community of inventors

Aachen, Germany

Peter E Geittner