Patek Philippe - Ref. 5236P In-line Perpetual Calendar

Day, date, and month are all shown in a single panoramic aperture at 12 o’clock. This in-line display was already adopted in some of the manufacture’s pocket watches but never before in a wristwatch. In fact, as you can imagine, this requires a high degree of miniaturization with many technical challenges.info: xtime-store

The 46 mm Patek Philippe Ref. 725/4 pocket watch that inspired the new 5236P. For this specific piece, the movement was manufactured in 1956 and encased in 1971. Thanks to its larger case, it featured a single date disk, moving around the day of the week indication, with the 31 dates. Note the date notation in the American format.
Picture courtesy of Christie's.info: xtime-store

To achieve the originality of this dial while combining legibility and reliability, Patek Philippe developed the new self-winding movement 31-260 PS QL with an additional in-line display module, for which three patent applications have been filed in 2019:

This display system featuring two “double ball bearings with coplanar balls” makes it possible for all the indications of the perpetual calendar to appear on one line in the same plane and without overlapping.

This mechanism improves the reliability of the date display as well as the perfect synchronization of the two numeral disks by suppressing a second jump of the date in the event of a jolt or when the date is being corrected.

This mechanism assures that the unit remains in its position when the switch from the 31st to the 1st of the following month takes place. This is handled by a 31-point star from which two teeth were removed.

The in-line display system relies on four disks (of which two for the date) that are arranged on one level. It consists of 118 additional parts. It is complemented by two round apertures, one at 4 o'clock for the leap year cycle and one at 8 o'clock for the day/night indicator. info: xtime-store

A further window displays the moon phases at 6 o'clock, encircled by the small seconds. info: xtime-store

To facilitate the adjustment of the functions, three correctors – for the day, the date, and the month – are recessed in the case flank between 9 and 2 o’clock, in the same order as the respective displays. The moon phase corrector is positioned at 8 o'clock.info: xtime-store

Featuring a recessed micro-rotor, the 31-260 PS QL calibre beats at the frequency of 4 Hz (28,800 vibrations per hour) with an autonomy of 38 hours to 48 hours.info: xtime-store

Completed by applied hour markers and baton hands in white gold, the beautiful vertical satin-finished blue dial with black-gradient rim is framed by a precious fully hand-polished 41.3 mm x 11.07 mm platinum case that offers water resistance to 30 metres / 100 feet. info: xtime-store

The new Patek Philippe Ref. 5236P-001 In-line Perpetual Calendar is matched to a navy blue alligator leather strap, secured to the wrist by a fold-over clasp, and has a price of Euro 115,060.info: xtime-store