Discharge lamp, method for manufacturing the discharge lamp electrode, lighting system

摘要

It is possible to prolong service life of a discharge lamp of hot-cathode type and to reduce a diameter thereof. A discharge lamp 1 is provided with an electrode 3. The electrode 3 has a heater 4 made up a coil portion 4a, and a first lead wire portion 4b and a second lead wire portion 4c that respectively extend from rear ends of this coil portion 4a and applied by an electron emission material 3a. In the electrode 3, a first lead-in wires 6a is connected to the first lead wire portion 4b and a second lead-in wires 6b is connected to the second lead wire portion 4c, so that the coil portion 4a is arranged vertically along the tube axis of the glass tube 2. The electrode 3 is also provided a sleeve 7 covering surrounding of the coil portion 4a and having openings in the faces respectively opposite to the forward end and rear end of the coil portion 4a. An open end 7a of the sleeve 7 exceeds a forward end of the coil portion 4a, thereby protecting the coil portion 4a.