Clock calendar display indexing mechanism - uses differential bearing between clock stepping motor and month shaft allowing additional indexing at end of month

摘要

The indexing mechanism is combined with a clock which is driven by a stepping motor. The latter is also used to drive the month shaft of the calendar mechanism via a differential gearing, during the daily running time of the calendar indexing mechanism, to index it by an amount corresponding to one day. Pref. the clock has an AC stepping motor which rotates once in the differential coupling being engaged to allow rotation of the month shaft once each 24 hours via a magnetic coupling or via a cam-operated ratchet mechanism. The differential coupling is also engaged to allow further indexing of the month shaft at the end of each month having less than 31 days. The motor pulses are obtained via an electronic circuit with a number of counter stages coupled via logic gates (20-25) to the control transistors (17,18,19) for the series coupled stator winding pairs (11,14;12,15;13,16).