Luminescent material for mercury discharge lamp including phosphor and a continuous protective layer

A mercury discharge lamp comprising:

• a light transmissive bulb;
• a luminescent layer including a phosphor material formed on an inner wall of the light transmissive bulb;
• a quantity of mercury and a quantity of rare gases filled in the light transmissive bulb;
• and
• means arranged for generating positive column discharge in the light transmissive bulb, wherein the phosphor material includes a protective layer continuously formed thereon and containing at least one metal oxide selected from the group consisting of MgO, Y.sub.2 O.sub.3, La.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Gd.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Ho.sub.2 O.sub.3, Er.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Lu.sub.2 O.sub.3, CaO, ZrO.sub.2, SrO, BaO, .alpha.-Al.sub.2 O.sub.3, and BeO for suppressing the deterioration of the phosphor material, said protective layer being formulated from an alcohol solution containing metal alkoxide.

A mercury discharge lamp comprising:

• a light transmissive bulb;
• a luminescent layer including a phosphor material formed on an inner wall of the light transmissive bulb;
• a quantity of mercury and a quantity of rare gases filled in the light transmissive bulb;
• and
• means arranged for generating positive column discharge in the light transmissive bulb, wherein the phosphor material includes a protective layer continuously formed thereon and containing a metal oxide, said protective layer being formulated from an alcohol solution containing metal alkoxide, such that said protective layer has more than 80% spectral transmittance for ultraviolet radiation at 254 mn and less than 50% spectral transmittance for ultraviolet radiation at 185 nm.

A mercury discharge lamp comprising:

• a light transmissive bulb;
• a luminescent layer including a phosphor material formed on an inner wall of the light transmissive bulb;
• a quantity of mercury and a quantity of rare gases filled in the light transmissive bulb;
• and
• means arranged for generating positive column discharge in the light transmissive bulb, wherein the phosphor material includes a protective layer continuously formed thereon and containing a metal oxide, said protective layer being formulated from an alcohol solution containing metal alkoxide, such that said protective layer has an energy gap of 5 electron volts to 8 electron volts at a forbidden band thereof for effectively absorbing ultraviolet radiation at 185 nm.

A lamp device comprising:

• a mercury discharge lamp including a light transmissive bulb, a luminescent layer that includes a phosphor material and is formed on an inner wall of the light transmissive bulb, the phosphor material including phosphor particles, a quantity of mercury and a quantity of rare gases filled in the light transmissive bulb and first means arranged for generating and sustaining positive column discharge in the light transmissive bulb,
• wherein the phosphor material includes a protective layer continuously formed thereon and containing at least one metal oxide selected from the group consisting of MgO, Y.sub.2 O.sub.3, La.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Gd.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Ho.sub.2 O.sub.3, Er.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Lu.sub.2 O.sub.3, CaO, ZrO.sub.2, SrO, BaO, .alpha.-Al.sub.2 O.sub.3, and BeO for suppressing the deterioration of the phosphor material, said protective layer being formulated from an alcohol solution containing metal alkoxide;
• and
• a lamp fixture for fixing the fluorescent lamp, said lamp fixture including electrical circuit means for supplying electric energy to the first means for generating and sustaining the positive column discharge.