Presented at Basel world 2008 in the category “Exceptional Watches”, the Ref. 5207 Grand Complication watch from Patek Philippe incorporates minute repeater, instantaneous perpetual calendar and tourbillon complications. This timepiece elevates the perpetual calendar to a new level of technical ingenuity. Its instantaneous perpetual calendar with aperture displays for the day, date, month, and leap-year cycle. Additionally, the Ref. 5207 features a moon phase display and a day/night indication.
The most conspicuous facet of Patek Philippe’s new, highly complicated masterpiece is its understated look. At first sight, it projects the classically sleek, round form of a Calatrava with a balanced, easily legible dial. It takes a closer look to see the slide for the minute repeater, and the tourbillon, as always in Patek Philippe watches, is visible only through the case back.
Instantaneous Perpetual calendar
This timepiece incorporates a spectacular arrangement of perpetual calendar functions on its dial to enable the minimalistic and clear display of indications. While, all indications starting from day, date, month, day/night, moon-phase and leap year are always visible on the dial, one special function of the perpetual calendar mechanism, the instantaneous switching of all calendar displays, can only be seen at midnight. This extremely elaborate, additional complication comprises 212 components.
Depending on the design of the mechanism, it takes mechanical calendar watches anywhere from 20 minutes to several hours to switch the displays. The greatest amount of energy is expended around midnight on February 28, when the date ring has to be moved forward by no fewer than four days to switch to the first of March. It is precisely this problem that preoccupied Patek Philippe’s designers and master watchmakers for a long time. They spent five years developing a mechanism that could instantaneously and simultaneously switch the day, date, month, and leap-year aperture displays at midnight. The heart of their invention is a mechanism composed of levers and program cams for which two patent applications have been filed.
The entire instantaneous perpetual calendar mechanism was designed as a module that can be integrated into an existing movement. In the case of the new Ref. 5207, the host movement is the coveted caliber R TO 27 PS, which, together with the instantaneous perpetual calendar, becomes the caliber R TO 27 PS QI movement: R stands for répétition minutes (minute repeater), TO for tourbillon, 27 for a diameter of 27 mm, PS for petite seconde (seconds subdial) and QI for quantième perpétuel instantané (instantaneous perpetual calendar).
In the new caliber, a 425- millimeter long mainspring coiled up in a barrel with an inside diameter of 9.18 millimeters must reliably execute all functions of the watch for approximately 48 hours – including the simultaneous and instantaneous advance of all calendar indications at midnight.
One of the challenges in this particular instance is that switching does not involve advancing dainty, featherweight hands. In this watch, the displays are aperture types with disks that assure excellent legibility but whose mass is several orders of magnitude greater than that of hands. Nonetheless, the specifications for the new instantaneous perpetual calendar stipulated that all displays must switch dependably, even with a residual power reserve of merely 2.5 hours. To address this difficult task, Patek Philippe developed a calendar mechanism for which two patent applications were filed (published European patent application No. EP 1734419 A1 and Swiss patent application No. 01080/07).
The first patent-pending innovation relates to the activation of the calendar indications with a large yoke. It is controlled by a four-toothed rack connected to a month lever that samples the annual program cam. This cam is connected to further switching cams via articulated arms, and controls the concurrent, instantaneous switching of the date, day, month, and leap-year disks. These processes explain the complex shape of this large yoke. It consists of fifteen individual parts, some of which are movable. Annual programming relies on a months cam with a variable February planetary cam that changes its profile every four years.
The second patent application involves the daily tour de force of calendar switching. At the end of months with 31 days, the date ring only needs to be advanced by one day. If a month has 30 days, the 31st day on the date ring must be skipped. In leap years, the ring must skip two days when switching from February 29 to March 1. And in normal years, the instantaneous advance motion must skip three days to jump from February 28 to March 1. This gradually increases the path and the angular deflection of the large yoke while narrowing the angle between the large yoke and the axis in which the driving spring acts, thus gradually weakening the spring’s resultant force.
This declining force cannot be offset simply by choosing a stronger spring in the first place because at the end of long months, this would increase the risk of the date ring bouncing forward to the 2nd or 3rd day of the month instead of stopping at the 1st. Thus, the engineers had to find a solution for advancing the date ring with the same controlled force regardless of the number of days in any given month. Patek Philippe invented a system with two equally strong springs that act in different directions.
In long months, the large yoke is connected only to the first spring because of its steep angle. Its energy is sufficient to advance the date ring (and the other calendar displays) by one or two days in an instantaneous and controlled manner. But the more the yoke is deflected, the weaker the force of the first spring becomes. When a certain angle is exceeded, the large yoke comes into contact with the second spring whose force vector deviates by about 45° from that of the first spring:the weaker the force exerted on the large yoke by the first spring, the stronger the effect of the second spring. This assures that even at the end of February, the calendar displays are advanced with a controlled amount of energy. This is the second innovation for which a patent is pending(Swiss patent application No. 01080/07). am. At this time, the large yoke is completely quiescent, so the amplitude of the balance wheel remains unaffected by movements of the calendar mechanism.
The Minute Repeater
Thanks to more than 160 years of experience, Patek Philippe has evolved the art of making exceptional minute repeater wristwatches to an unprecedented degree of perfection. When the owner of a Ref. 5207 activates the slide and listens to the watch as it first counts the hours on a low-pitched gong, then indicates the quarter hours with double strikes on both gongs, and finally tallies the number of minutes that have elapsed since the last quarter on the high-pitched gong.
It took many years of research to develop the best steel alloy and optimize the shape and attachment of the gongs in cooperation with the internationally respected Swiss Federal Institute of Technology in Lausanne. It may not be surprising that the manufacture’s president, Philippe Stern, repeatedly listens to the sound of each of these rare watches before deciding whether the exceptional masterpiece is ready for delivery or must return to the workshops for acoustic tweaking. The sound, which for Philippe Stern constitutes the acoustic signature of Patek Philippe, has been recorded and digitized in an anechoic chamber to preserve it as a reference for all time.
The third highlight of the Patek Philippe Grand Complication Ref. 5207 is the tourbillon escapement that keeps the rate of the watch extremely steady even in vertical positions. It has a steel cage that rotates about its own axis once a minute. It consists of 69 individual parts and weighs a scant 0.3 grams. All steel parts are separately angled, satin-finished and ground or polished by hand.
Like all Patek Philippe wristwatches with tourbillons, the Ref. 5207 also comes with a certificate issued by Switzerland’s official chronometer testing agency, C.O.S.C. (Contrôle Officiel Suisse des Chronomètres).
After it has passed the C.O.S.C. tests, each chronometer is submitted to Philippe Stern who personally decides whether it deserves the inscription “Patek Philippe Tourbillon” or whether the entire procedure needs to be repeated. Since the in-house specifications at Patek Philippe are at least twice as demanding as those of the official testing agency, it is not uncommon for a movement to be precision adjusted a second time and then again sent to the C.O.S.C. The serial number of the movement is mentioned on the agency’s certificate for positive identification purposes. The same serial number is also inscribed on the dial of the tourbillon wristwatch, but otherwise, nothing else suggests that the timepiece embodies this horological distinction.
The tourbillon cage is lubricated with oil that can react to the ultraviolet radiation in sunlight and could age prematurely if exposed to it. For this reason, Patek Philippe deliberately does not display the tourbillon through the dial. However, the solid-platinum case back of the watch can be replaced with an included sapphire-crystal back.
The 41-millimeter, classic Calatrava-style platinum case of the Ref. 5207 is made using the traditional cold-forming technique. It is crafted in-house with high-tonnage presses. Its flanks and the minute-repeater slide are hand-engraved, and like all Patek Philippe platinum cases, it features a discreetly set Top Wesselton diamond between the lugs at 6 o’clock.
The “Honey Gold”-hued 18K gold dial beneath the slightly domed crystal reveals an unusual arrangement of displays for perpetual calendar functions. The apertures in mirror-polished frames show the day, date, and month along an arc between 10 and 2 o’clock. The date display with its mirror-polished white-gold frame is particularly prominent. The seconds subdial at 6 o’clock has an aperture for the moon-phase display, a poetic yet highly precise indication that deviates from the true lunation by only one day in 122 years. To its left is a small aperture for the day/night indication. The aperture on the opposite side shows the leap-year cycle with Roman numerals I to IV.
The Ref. 5207 is among Patek Philippe’s most complicated wristwatches; only very few of these watches will be crafted each year. Because of this limited availability, the Ref. 5207 will be sold exclusively in the Patek Philippe Geneva Salons during the introductory phase.
Model: Grand Complication Ref. 5207 in platinum with minute repeater, instantaneous perpetual calendar in apertures, tourbillon, and moon-phase display
Caliber R TO 27 PS QI
Manually wound mechanical movement, tourbillon, minute repeater, instantaneous perpetual calendar. Apertures for day of week, date, month, leap-year cycle, day/night indicator, moonphase display, and seconds subdial.
Overall diameter: 32 mm.
Height: 9.33 mm
Number of parts: 548
Number of jewels: 35
Power reserve: max. 48 hours
Frequency: 21,600 semi-oscillations/hour (3 Hz)
Tourbillon: Tourbillon cage in steel, 69 parts, 0.3 grams 1 rpm. Tourbillon on one axis with balance and fourth wheel
Balance spring: Breguet
Balance spring stud: Movable
– Pulled out: to set the time
– Pushed in: to wind the watch
Exclusive certificate issued jointly by the C.O.S.C (Contrôle Officiel Suisse des Chronomètres) and the Geneva Seal. Hallmark: Geneva Seal
With hands: Center hours and minutes & Seconds at 6 o’clock
– Day of week between 10 and 11 o’clock in polished white-gold frame
– Date at 12 o’clock in a polished white-gold frame
– Month between 1 and 2 o’clock in a polished white-gold frame
– Moon phase at 6 o’clock
– Day/night indicator between 7 and 8 o’clock
– Leap year cycle between 4 and 5 o’clock
Corrector push pieces
– Day between 11 and 12 o’clock
– Date between 6 and 7 o’clock
– Month between 12 and 1 o’clock
– Moon phase between 5 and 6 o’clock
Stylus in ebony and white gold included. Minute repeater with small strike (hours) on the 1st gong, minutes on the 2nd gong, and quarter hours on both gongs.
950 platinum, delivered with solid-platinum back and interchangeable sapphire-crystal back; diamond with approx. 0.02 ct. between the lugs at 6 o’clock
Dimensions: Diameter: 41 mm
Height: 16.25 mm
Width between lugs: 20 mm
Slide: In the side of the case to start the minute repeater
18K gold, Honey Gold hue (New exclusive Patek Philippe dial color)
11 hour markers in 18K white gold
Dauphine hands in 18K white gold for hours and minutes
Baton seconds hand with counterweight, 18K white gold
Minute scale on periphery of dial
Shiny brown alligator with rectangular scales, hand-stitched, 116- mm prong buckle in platinum