Abstract: The manufacturing method comprises: a softening step of softening a straight glass tube in a heating furnace; a moving and placing step of moving the softened glass tube so that the glass tube is placed on the top of the mandrel; and a winding step of winding the glass tube placed on the top of the mandrel around the periphery of the mandrel. The mandrel is disposed beneath the glass tube starting to get soft, and the glass tube being soft is perpendicularly lowered in order to be placed on the top of the mandrel. In the winding step, the winding speed Vr at which the glass tube is wound around the mandrel is higher than the moving speed Vs at which chuck units holding the ends of the glass tube move toward the mandrel.

Abstract: An objective is to provide a compact self-ballasted fluorescent lamp which can reduce occurrence of a short circuit without protecting lead wires extending from each end portion of a spiral arc tube. To achieve the objective, a pair of connection pins is provided on a circuit board of the compact self-ballasted fluorescent lamp, near a periphery of the circuit board so as to oppose another pair of connection pins formed near the periphery. In this way, the pairs of connection pins can be respectively provided directly above the end portions of the spiral arc tube. Thus, lead wires extending from each of the end portions can be connected to a corresponding one of the pairs of connection pins with a relatively short distance. This prevents the lead wires from being in contact with the circuit board, thereby reducing occurrence of a short circuit.

Abstract: A lamp includes an arc tube and a lighting unit for lighting the arc tube. The lighting unit includes a rectifier circuit, a smoothing circuit for partial smoothing, and an inverter circuit having a pair of switching elements. The smoothing circuit smoothes portions of the output voltage of the rectifier circuit below the first voltage value and outputs a voltage that falls between the first voltage value and the second voltage value. The discharge sustaining voltage of the arc tube is set to fall between the first and second values of the voltage Vdc output from the smoothing circuit.

Abstract: An arc tube is formed by a glass tube that is turned at a substantially middle thereof and wound around a spiral axis from the middle, to have a double-spiral structure. End portions of the arc tub are wound around the spiral axis. A holder has insertion openings formed therein in such shapes that correspond to shapes of the ends of the arc tube. The insertion openings allow the ends of the arc tube to be inserted along a bottom wall of the holder. The holder also includes guide grooves provided in the areas before the insertion openings in the spiral direction of the ends of the arc tube. The guide grooves allow the end portions of the arc tube to come in contact, and when the arc tube is rotated around the axis, guide the ends of the arc tube to the insertion openings.

Abstract: An arc tube is composed of an arc tube body that is formed by winding a straight glass tube. Two portions of the straight glass tube are spirally wound around an imaginary conical surface. The spiraled portions of the glass tube are sandwiched between a pair of movable fixed plates. The spiraled portions of the glass tube are heated to a temperature equal to or higher than a point at which the glass tube is deformable and yet lower than the softening point of the glass tube. The spiraled portions are flattened by the movable plate moving downwardly under its own weight.

Abstract: This invention aims at providing a low-pressure mercury lamp having an improved luminous efficiency while maintaining the compactness and long life of the arc tube. This lamp comprises an arc tube formed by bending a glass tube. This arc tube is formed into a double-spiral structure comprising: a turning part located in substantially the midsection from both ends of the glass tube; a first spiral part starting from one of the ends and spiraling around the pivotal axis to reach the turning part; and a second spiral part starting from the turning part and spiraling around the pivotal axis to the other end. The glass tube has a circular shape in cross section with 7.4 mm inner diameter. This low-pressure mercury lamp is a 12 W lamp alternative to a 60 W incandescent lamp, and the bulb wall loading under steady state illumination is set at 0.103 W/cm2.

Abstract: Disclosed is a compact self-ballasted fluorescent lamp that includes a phosphor coating provided inside a glass tube bent to have a double-spiral configuration. The arc tube has two spiral parts that are wound around an axis “A”, and a turning part joining the two spiral parts. At any cross section of the glass tube, the applied phosphor coating is thicker in the inner surface of the glass tube near the ends of the glass tube in the axis “A” direction, than in the inner surface near the turning part.