Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium
Patent
1995-06-15
1997-03-25
Oberley, Alvin F.
Electric lamp and discharge devices
With luminescent solid or liquid material
With gaseous discharge medium
313346R, 313346DC, 445 51, H01J 904
Patent
active
056147848
ABSTRACT:
The lifetime of cold-start fluorescent lamps is increased, and the ability to withstand repeated ON-OFF switching cycles enhanced by coating the electrodes with an emitter which consists of barium oxide and a small portion of metallic barium and, optionally, up to 20 mol-% of strontium oxide and a small portion of metallic strontium, preferably only up to about 5 mol-% of strontium oxide--metallic strontium. To make the emitter, barium carbonate, optionally mixed with strontium carbonate, is applied in paste form to the electrodes which, when coated, are introduced into an envelope and sealed therein. The envelope is then evacuated, and the electrodes are heated,
thus converting the barium carbonate to barium oxide and metallic barium, and the strontium carbonate, if present, to strontium oxide and metallic strontium, so that the electrodes will be coated with barium oxide, optionally strontium oxide, and metallic barium and optionally metallic strontium. The evacuation and activating step can be carried out essentially simultaneously, by evacuating the envelope through a pump tube and heating the electrodes to above about 800.degree. C. by passing a current pulse therethrough.
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Harzig Christian
Hoffmann Roland
Weinhardt Erolf
Oberley Alvin F.
Patent-Treuhand-Gesellschaft fur elektrische Gluhlampen mbH
Richardson Lawrence D.
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