Magnetic watch screening combining shock and dirt proofing - using annulus connected to closed front and rear discs and fixed to removable segments

摘要

The device is for screening small sensitive indicator instruments against external magnetic, mechanical, and contamination source effects is partic. applicable to watches and partic. effective against magnetic effects. Shock and dirt proofing are also achieved with practically no increase in size. The screening consists of an annulus (1) exhibiting magnetic field, lines enclosing the mechanism (3) laterally at least over the height of the mechanism. The annulus has fixed or removable screening segments projecting toward the centre of the mechanism so as to cover particularly sensitive parts of the mechanism. The closed front disc (2), esp. the dial, is connected to the annulus and itself consists of material exhibiting magnetic field lines and tending to concentrate them. A closed rear screening plane (4) is also connected to the annulus.