| 摘要 |
<p>A device for advancing and retracting a writing element (R) in a writing instrument, of the type comprising a cylinder (1), a stationary cam (2) provided on an inner surface of the cylinder, a rotary cam follower (5) disposed inside the stationary cam (2) to be rotatable and slidable axially of the cylinder, the rotary cam follower (2) being in abutting engagement at a front end thereof with the writing element (R), and a knocking rod (3) disposed in the cylinder (1) and having a front cam portion (4). When the knocking rod (3) is pushed forward, the knocking rod (3), the stationary cam (2) and the rotary cam follower (5) cooperate to advance the writing element (R) and maintain the same in an advanced position and to allow the writing element (R) to retract to a retracted position. The knocking rod (3) has projections (6) which are in slidable engagement with slots (7) formed axially through the cylinder (1). The knocking rod (3) has slots (9) to make it resilient. The knocking rod (3) is inserted into the cylinder (1) through the rear opening (1a) of the cylinder until the projections (6) snappingly engage the slots (7). The capability of inserting the knocking rod (3) from the rear side makes the assembly easy and simple.</p> |
