Positioning mechanism for a center wheel

Positioning mechanism for a centre wheel which is moved in steps in an electronic timepiece with analog display having an indicator attached to said centre wheel, said timepiece being of a type including a stepping motor and a jumper spring of which a first end is provided with two inclined planes adapted to cooperate with teeth of the centre wheel and the second end is rotatably mounted with friction fit into the base plate, said positioning mechanism comprising:

• a gear train coupled between the stepping motor and the centre wheel through which the motor drives the centre wheel in steps, said gear train comprising at least a pinion, a gear and a friction mounting means for mounting said pinion to said gear by friction which is sufficiently high so that in normal operation of the timepiece transmission of motion is made without slippage between the pinion and the gear to drive the indicator, however low enough so that it is possible to manually cause slippage of the pinion relative to the gear;
• means for manually causing said slippage to adjust the position of the centre wheel relative to step positions of the motor to bring the two inclined planes of the jumper spring into proper coincidence with a tooth space on said centre wheel at each tooth position for precisely positioning the indicator relative to markings of the dial of the timepiece between steps.