U.S. Philips Corporation

Willem L Konijnendijk

Petrus J Willemsen

Robert C Peters

Willebrordus H Van De Spijker

Gert M Boogerd

Henricus L Tonnaer

Low-pressure mercury vapor discharge lamp suitable for use in photo-therapy and having a glass discharge tube which is opaque to shorter wavelength ultraviolet radiation and bears a luminescent layer on its inside surface. A problem in such lamps is to produce a useful quantity of radiation which is effective for photo-therapy in combination with as low a quantity of erythema-producing radiation as possible. The luminescent layer comprises a luminescent material having the characteristic line emission of gadolinium at 312 nm, and the glass has an absorption edge located between 280 and 305 nm.

Low-pressure mercury vapor discharge lamp

A low-pressure mercury vapor discharge lamp for radiation purposes having a discharge tube made of glass with selective transmission, the tube being coated on the inside with a luminescent layer. This layer contains a luminescent material which has the characteristic line emission of gadolinium at 312 nm. The discharge tube is made of glass having an absorption edge located between 260 and 280 nm and the tube has at 312 nm a transmission of at least 80%.

Luminescent alkaline earth metal silicate aluminate defined by the formula Sr.sub.3-a-b Ba.sub.a Ca.sub.b Si.sub.1-y Ge.sub.y Al.sub.10-z Ga.sub.z O.sub.20 ; Ce.sub.p.sup.3+, Eu.sub.q.sup.2+, Tb.sub.r.sup.3+, wherein, if r=0, it holds that

Luminescent material with alkaline earth metal silicate aluminate host

Luminescent lead-activated alkaline earth metal rare earth metal borates having compositions defined by the formula Me.sub.1-p Pb.sub.p La.sub.1-x-y Y.sub.x Gd.sub.y BO.sub.4, where Me represents strontium and/or calcium, where 0.005 .ltoreq.p.ltoreq.0.30 and 0.ltoreq.x.ltoreq.0.1, and where O.ltoreq.y.ltoreq.0.5 when at least 75 mole% of Me is Ca and O.ltoreq.y.ltoreq.0.1 when less than 75 mole% of Me is Ca. The borate may be used in the luminescent screen of low-pressure mercury vapor discharge lamps.

Growing community of inventors

Eindhoven, Netherlands

Willem L Konijnendijk