PURPOSE: To improve the mechanical strength of a bulb and prevent the bulb from being damaged by comprising a wall that partitions adjacent discharge paths so as to form a shared wall of these adjacent discharge paths or to be touched mutually.
CONSTITUTION: A bulb 10 forms U-shaped discharge paths 11 between electrodes 1 and 1 by bending a direct tube type bulb that seals the electrodes 1 and 1 on both ends in a U-shaped form at the central part. Since the discharge paths 11 are U-shaped, the linear discharge paths are mutually adjacent. These adjacent linear discharge paths are partitioned by a partition wall 12. When the direct tube type bulb is bent in a U-shaped form at the central part, this partition wall 12 makes the bulb walls touch mutually and is integrated by heating and fusing this contact wall. Consequently, the partition wall 12 forms a shared wall that partitions adjacent linear discharge paths. After such molding, a curved bulb is completed by bending and molding the bulb almost annularly so that sealing sections 3 and 3 can come close to a bending section 4.
ITOU HIDENORI
KOJIMA YOSHIO
HARA NOBUKO
HASUDA AKIKO
