| 摘要 |
An electro-magnetically operated device is described in which a magnetisable armature, typically a length of thin naturally resilient mild steel, is sandwiched between, and extends from, two parts of a magentic circuit which contains an air gap into which the armature extends. An electromagnet polarizes the armature along its length so as to cause the end thereof in the air gap to be attached to one or the other of the two poles of the magnetic circuit defining the gap. The armature is designed so as to be capable of adopting a mid-position between the poles of the air gap if the curent flowing in the electromagnet is reduced to zero. Equalising the air gaps and adjusting the size of the gap relative to the resilience of the armature will produce a bistable characteristic in which the armature will not remain in the mid-position, but will always remain in contact with one pole or the other, and is shifted from one to the other by a pulse of current of appropriate polarity. Adjustment of the size of the air gap on one side or the other of the armature introduces an out of balance in the magnetic circuit enabling the device to adopt a monostable characteristic instead of a bistable characteristic. |
