| 摘要 |
PROBLEM TO BE SOLVED: To secure the quantity of emission required for sufficient preliminary ionization without increasing the size of a device by forming the edge development length of the contact part between a corona electrode toward main discharge space and a dielectric pipe, so that it is longer than the shaft length of the dielectric pipe. SOLUTION: When a high voltage is applied between a rear electrode 41 and a corona electrode 12, a corona discharge is started at the contact part between a dielectric pipe 42 consisting of straight lines 13 and 14 and curves 15 and 16 and the corona electrode 12, the corona discharge is developed in the outer periphery of the dielectric pipe 42, and ultraviolet rays are applied toward main discharge space. In this case, a contact angleθ(a radian angle) is a center angle consisting of both ends 17 and 18 of the curve 15 or 16, the straight lines 13 and 14 are set to a desired length, the contact distance between the dielectric pipe 42 and the corona electrode 12 becomes longer by the amount in the expression (D/2)×θ×2n=nDθas compared with a linear preliminary ionization electrode when n curves 15 and 16 exist, thus increasing the quantity of the emission of ultraviolet rays by that amount and performing sufficient preliminary ionization through the main discharge space. |
