| 摘要 |
<p>MECHANICAL PENCIL A low-cost mechanical pencil employing an improved lead-driving mechanism in which there is cooperation between a low-cost, helical spring member through which moves a lead advance-retract member which is keyed to longitudinal grooves in the inner barrel wall. If the lead is subjected to excessive pressure during use, it is caused to partially retract into the tip by virtue of axial compression of the helical spring, thereby reducing the likelihood of lead breakage.</p> |
