| 摘要 |
<p>The electromagnetic device can drive the characters in a high speed line printer, typically attached to the output of a computer. Two C-shaped ferromagnetic cores (24,27) are placed face to face with an air gap between opposing limbs. Each core has an individual winding (23,26) enclosing the whole core. The moving armature (18) is located in the air gap. It comprises a carrier of non-magnetic low density material (19) with ferrmagnetic inserts (20,21) at each end. The spacing between inserts corresponds to the spacing between limbs of the core, and the volume of ferromagnetic material is approx. equal to the air gap volume. At rest the inserts are clear of the gap and are linked by the smallest amount of flux. The inserts can be chevron shaped to assist with this requirement. When the coil is energised the armature moves rapidly into the gap. The coil switches off when the in-ine position is reached. Inertia carries the armature on into the working part of the stroke which presses the character against the paper.</p> |
