The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 25, 1997
Filed:
Jun. 15, 1995
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.