THE HISTORY OF BLANCPAIN

The Leman Flyback Grand Date. The Leman Tourbillon Diamond.
mattered and the goal was to achieve a larger
date than others in the industry for
movements of comparable size. That criterion
was only a starting point. Beyond size, Blancpain
sought an instant change, where the
norm was either a slow change around midnight
or, slightly improving upon that, a semiinstantaneous
change. Upping the engineering
ante still further, Blancpain insisted
upon absolute assurance that the display
would be reliably blocked from succumbing
to shocks that provoked other large date
designs into nonsensical readings such as
“32” (following which a trip to the repair
centre would be guaranteed). Finally the
mechanism had to be energy efficient, consuming
little more power from the mainspring
barrel than existing small date complications.
Energy conservation would allow
incorporation of the complication without
severe effects on the movement’s power
reserve.
Not only did Blancpain hit every one of
the targets with its module 69 design, it
achieved one other prized criterion – thinness.
The bulk of the pre-existing large date
WHEN BLANCPAIN UNDERTOOK TO DEVELOP ITS MODULE 69
LARGE DATE MECHANISM THE REQUIREMENTS WERE FAR MORE
RIGOROUS THAN MERE SIZE, DRIVE AND SYNCHRONISATION.
64
| 65
designs were quite thick, causing an undesirable
bulking up of the movement.
To most easily understand the calibre 69’s
mechanism, it is best to divide it up into sections,
exploring each individually:
1. the system of the 24 hour wheel
and instant date change cam;
2. the date change for single digits
and the actuating/blocking spring;
3. the system for changing the tens disc, and
4. the system for rapid date change
via the crown.