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Cathodoluminescent light sources and electric lighting arrangements including such sources

  • US 4,506,194 A
  • Filed: 05/16/1983
  • Issued: 03/19/1985
  • Est. Priority Date: 08/19/1982
  • Status: Expired due to Fees
First Claim
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1. In a cathodoluminescent lamp including an evacuated bulbous glass envelope with an integral glass neck closed by a pinched glass foot tube incorporating an exhaust tube located around the longitudinal axis of the foot tube, the foot tube terminating in a cap, an anode constituted by an electrically conductive coating on at least part of the interior surface of the bulb wall, such that at least part of the bulb wall is light-transmissive, a layer of phosphor on the whole of the interior of the bulb wall and overlying the said anode coating, which phosphor is excitable to luminescence by electron bombardment, a dome-shaped grid location within the bulb adjacent to the junction between the bulb and neck of the envelope and supported by a hollow metal cylinder disposed coaxially within the neck, an electron emissive cathode mounted within the assembly of the grid and its supporting cylinder, electrically conducting leads, all located wholly within the envelope neck and foot tube, connecting the anode, grid and cathode to respective external contacts carried by the said cap for connection to a circuit arrangement for operation of the lamp from a source of electric current supply, the improvement comprising an additional glass tube provided within the foot tube, extending from the pinch substantially parallel to the exhaust tube and adjacent to the wall of the foot tube, the lead to the anode passing through the said additional tube and being sealed through the pinch, the leads to the cathode and grid passing through the foot tube, and being sealed through the pinch in locations at the side of the exhaust tube remote from the said additional tube and anode lead, and an internal anode contact provided on the interior surface of the envelope neck in the form of a metal strip, the end portions of which are secured to the glass of the neck and the central portion of which is bent so as to be upstanding from the neck surface, the said anode coating extending from the bulb over the internal neck surface to a level beyond that of the said metal strip, so as to cover the said end portions of the strip, and the inner end of the anode lead being inserted through, and being so shaped that it engages with the said upstanding portion of the metal strip.

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