Патент USA US2105138код для вставки
Jan. 11, 1938. J, |_, cox ' ‘ GASEOUS Emcmzc DISCHARGE LAMP I I Filed Oc-t. 28, . 2,105,138 I 1956 \ ‘ I k‘ \ ._ § k“ “ ‘ N \mlagl b ~ ,Y 7 I 5 4 '} I l I / / I l / \ I I I , I I I / I I I II ’ I j ? I I 6 I ’ z / I I I I 1 I / KNx/ENTOR: JAMES L. @ox BY: i A TTORNE Y. v Patented Jan. 11, 1938 ' 2,l05,l38 I - UNITED ,_ STATEE ' 2,105,138 GASEOIUS mrzc'rarc niscw i‘ : » James L. Cox, Denver's, Mass” ‘assignor to By grade Sylvania Corppration, Salem, Mass” a corporation at Massachusetts Application Uctober 28, K936, Serial No. 108,017 2 Claims. (m. 176-126) The present invention relates to electric gase ous discharge lamps, and in particularto such ,lamps which comprise a thermionic electrode ' which is attached to a metal disc used as a sealed 5 closure member for a glass envelope. An object of the invention is the provision of a refractory insulating coating for the metal disc in order to insure that the disc does not act as an electrode for the discharge. It is known, for example, that an electric dis charge lamp can'be made by enclosing a gaseous atmosphere at the proper pressure in a glass tube, or other envelo , whose open-ends are which generally accompanies the manufacturing process, and in addition it may allow the disc to act as a capacity member for starting the dis charge, and may facilitate the making of the metal to glass seal during manufacture. Such an electrode and disc can be used to ad vantage in any gaseous discharge tube, but par ticularly in those in which a ?lling of an inert gas and mercury is used. ' The drawing shows a side view of a lamp ac- l0 cording to the invention. ' A vitreous envelope I has the metal discs 2 and 3 sealed to its ends, closing them oil’. Elec sealed to metal discs, the discs acting as elec 15 trodes. Such lamps require a high voltage, of trodes 4 and 5, attached to the discs may be of . the order of several hundred, for operation, and the thermionic type, if desired. They are pref- 15 produce sputtering of the electrodes on the glass, erably, but not necessarily, of the wire-wound blackening the latter. A thermionic electrode of oxide-coated type. They may be attached to high electron-emitting power can be attached to the metal discs by welding,.or some similar proc 20 the disc, thus reducing the operating voltage and ess. Welding generally weakens the disc, so I prefer to support the electrode from a wire 8, 9 2o the sputtering. To secure the proper tempera ture for such an electrode, it may be made in wrapped in a circular groove “I, ll formed on the form of a metal wire, wrapped if desired the disc. To permit this wrapping, and to facili with another wire of smaller diameter, and tate external connection to the disc, the latter 25 coated with a highly electron-emitting material. is preferably provided with a central raised por The larger wire, of course, can be arranged in tion l2, IS. The refractory insulating coating 6. 25 any convenient geometric shape. If desired, a ‘I preferably covers any wire wrapped around the , coated cup or disc of metal can be used instead central portion, thus not only insulating the sur face of the disc, but helping to make a rigid joint of the coated wire. 30 Such an electrode will attain, during operation, to the electrode lead.‘ In many cases, the con necting support between the electrode 4 (or 6) 30 an electron emitting temperature, and thus sup port the discharge. Its higher emitting qualities, and the disc 2 (or 3) should be covered with in sulation, to prevent the discharge from occur will insure that, during normal operating condi ring to it. ‘ tions the discharge will emanate from it, and not What. I claim is: 35 from the metal disc. However, during the man-' 1. An electric gaseous discharge lamp of the as ufacture of the lamp, it is necessary to pass a. discharge between the electrodes before they are type having a ?lling of an inert gas and mer rendered thermionically emissive. During such cury vapor and comprising an elongated glass operation, the discharge tends to, start from the tube having sealed across each of its ends a 40 disc, causing sputtering of the metal, with a metal closure disc with an inward peripherally _ consequent black deposit on the glass near the grooved protuberance of smaller diameter than 40 metal discs. To prevent this, and to insure that, said disc, a wire wrapped around said protuber even during the manufacture of the lamp, the ance and in said groove, an alkaline earth oxide coated electrode supported from said wire, and a discharge emanates from the thermionic elec 45 trode, we have found necessary the use of a re fractory insulating material on the inside sur face of the metal disc. This coating may be, for example, of alumina. It may be put on as a paste of alumina, and water, then dried out. If de 50 sired, the insulating coating may be fused to the metal surface as a sort of glaze. Such a coating prevents the discharge from attacking the end cap during the preliminary operation at the lamp refractory insulating coating over the interior surface of the, disk and over the wrapped wire. 45 said coating bonding the disk and wire into con ductive contact and insulating them‘ from the gas ?lling inside the lamp. 2. An electric gaseous discharge lamp as in claim 1, in which the refractory insulating coat- 50 ing is of alumina. JAMES L. COX.