Electrode mount, arc tube, low-pressure mercury vapor discharge lamp, compact self-ballasted fluorescent lamp and method of manufacturing the arc tube

1. An electrode mount to be fixed to an end portion of an arc glass tube by a pinch-sealing of the arc glass tube, comprising:

a filament coil made of a wire wound in a coil configuration;

paired lead wires supporting the filament coil therebetween in a manner that the filament coil hangs across the lead wires; and

a retainer retaining the lead wires, wherein

the retainer is a glass bead disposed on part of the lead wires external to the arc glass tube and on an opposite side from the filament coil in relation to a region of the lead wires for application of the pinch-sealing, the region of the lead wires for the pinch-sealing being between the retainer and the filament coil.

2. The electrode mount of claim 1 , wherein

a distance between a central axis of a coil portion of the filament coil and an edge of the retainer, facing the filament coil, is such that the retainer does not interfere with a thin tube to be attached to the end portion of the arc glass tube during the pinch-sealing.

3. The electrode mount of claim 1 , wherein

the end portion of the arc glass tube is curved, and

part of the lead wires, to be disposed inside the glass tube, is bent to follow a shape of the end portion of the arc glass tube, the part of the lead wires being between the retainer and the filament coil.

4. The electrode mount of claim 2 , wherein

the end portion of the arc glass tube is curved, and

part of the lead wires, to be disposed inside the arc glass tube, is bent to follow a shape of the end portion of the arc glass tube, the part of the lead wires being between the retainer and the filament coil.

5. The electrode mount of claim 4 , wherein

the retainer is made of a glass material.

6. An arc tube comprising:

a glass tube having a discharge space therein; and

an electrode (i) including a filament coil, paired lead wires supporting the filament coil therebetween in a manner that the filament coil hangs across the lead wires, and a glass bead retaining the lead wires, and (ii) fixed to an end portion of the glass tube at part of the lead wires by pinch-sealing, wherein

the glass bead is disposed outside the glass tube and the filament coil is within the glass tube.

7. A low-pressure mercury vapor discharge lamp comprising:

an arc tube including a glass tube and an electrode fixed to an end portion of the glass tube by pinch-sealing; and

a base being a terminal for power supply to the arc tube, wherein

the electrode includes a filament coil, paired lead wires supporting the filament coil therebetween in a manner that the filament coil hangs across the lead wires, and a glass bead retaining the lead wires is disposed outside the glass tube and the filament coil is within the glass tube.

8. A compact self-ballasted fluorescent lamp comprising:

an arc tube including an electrode fixed to an end portion of a glass tube by pinch-sealing;

an electronic ballast operable to cause the arc tube to light; and

a case including a base, housing the electronic ballast therein, and retaining the arc tube, wherein

the electrode includes a filament coil, paired lead wires supporting the filament coil therebetween in a manner that the filament coil hangs across the lead wires, and a glass bead retaining the lead wires is disposed outside the glass tube with the filament coil within the glass tube.