| 摘要 |
The place shift-up mechanism of a digital clock comprises ratchet feed mechanism which permits manual setting of the clock even during the shift-up operation. The ratchet feed mechanism comprises an eccentric cam secured to a rotary shaft which also carries an eccentric operation pin. A ratchet wheel is rotatably supported by the shaft. A place shift-up lever is supported so as to be capable of rocking and sliding movement and has a forked leg plate with spaced legs receiving the eccentric cam between them. One leg of the forked leg plate has a feed pawl for engagement with the ratchet wheel and also a hook pawl engageable by the operation pin to move the place shift-up lever in one direction. The other leg of the forked leg plate has a return pawl which is engageable by the operation pin to move the plate shift-up lever in an opposite direction. The place shift-up lever is rocked by the eccentric cam and is moved by the operation pin first in one direction and then in the other to cause the feed pawl to engage the ratchet wheel to advance it one tooth for each revolution of the rotary shaft. |
