| 摘要 |
PURPOSE:To make broad the frequency band, by providing a permanent magnet so that it is bridged between exciting winding and yoke, providing a space at the bottom in the yoke, and linking the space between this space and that in the watch case. CONSTITUTION:A hollow disc or a plurality of sector type magnets 7 are provided so that they bridge between the exciting winding 6 and the sound main body yoke 3, and a space 8 is provided between the magnet 8 and the bottom of the sound body yoke 3. Further, at the bottom of the sound body yoke 3, a plurality of holes 14 are provided and a perforated member 15 is located to the holes 14. The space 8 and the space in the watch case are linked with the holes 14 and the space in the watch case is operated as a resonance chamber. |
