To solve the problem that the achievement of a mechanism that performs rotational regulation on a specific rotational direction only must be extremely difficult inside wheel trains of micro precision equipment like a wrist watch as a reversion prevention mechanism is required inside the gear wheels coupled to a pointer part from a motor, not to allow a reversal to take place in a pointer indication section when the continuous operations of pointers are attained using a rocking type step motor in a pointer type clock.
A reversion prevention mechanism is such that one set of main wheels composed of a plurality of gear pitches as a rotary shaft to be used commonly are constituted in a part of wheel trains, a plural sets of pinions having equal gear pitches with these gear pitches as another rotary shaft to be used commonly are allowed to be engaged with the gears. A circular-arc section with a rotary shaft as the center is provided in a gear with long gear pitches out of the sets of pinions, and this circular-arc may contact gears of long gear pitches out of sets of the main wheels.
FUKUSHIMA TOSHIAKI
MAEDA TOSHINARI
CITIZEN WATCH CO LTD