Patek Philippe | 10th Second Monopusher Chronograph

Patek Philippe has taken on a new mechanical challenge illustrated in the unveiling of its first wrist chronograph that measures and displays one-tenths of a second. To achieve this, the Manufacture has developed a new high-performance movement for which seven patent applications have been filed.

The Manufacture reasserts its competence and innovative spirit in the field of short-time measurement by presenting a manually wound movement with two separate chronograph mechanisms and sweep hands. One of them indicates tenths of a second – precisely and very crisply. This high-tech high-frequency caliber (5 Hz) with 31 patents, of which seven new patents are specific to the new mechanism, ticks in a platinum case with a blue dial and red accents. Its sporty design emphasizes the highly technical and performance-oriented facets.

To further push the boundaries of mechanical horology and delight aficionados of highly technical timepieces, Patek Philippe decided to develop its first movement for a wrist chronograph that can measure and display tenths of a second. For this purpose, the engineers relied on one of the in-house movements that had been developed during the past twenty years. This was Caliber CH 29-535 PS launched in 2009; it reflects traditional architecture (manually wound, column-wheel control, horizontal wheel clutch) enhanced with six patented innovations and is complemented by its split-seconds version with two sweep chronograph hands.

The first task was to increase the frequency of the movement. With a frequency of 4 Hz (28,800 semi-oscillations per hour that let the movement and the chronograph hands execute 8 jumps per second), Caliber CH 29-535 PS can merely measure eighths of a second. Conversely, the new Caliber CH 29-535 PS 1/10 beats at a frequency of 5 Hz (36,000 semi-oscillations per hour for 10 jumps per second) and thus enables tenths-of-a-second measurements. This is a premiere for a Patek Philippe wrist chronograph but it also requires more energy.

A sweep seconds hand alone and a frequency of 5 Hz would nonetheless not be sufficient to display tenths of a second with the desired accuracy. The dial of a wristwatch does not provide enough space for a scale with a microscopically tight tenths-of-a-second graduation. The designers thus resolved to provide Caliber CH 29-535 PS 1/10 with two independent chronograph mechanisms: one for the seconds and the instantaneous 30-minute counter, the other exclusively for measuring and displaying stopped tenths of a second.

A patented concentric display
With this decision, Patek Philippe opted for good legibility. In keeping with the Manufacture customer-centric creation philosophy, it was essential to ensure the ideally organized, fast and dependable readability of the chronograph’s tenths of a second, seconds and minutes measurements.

The engineers therefore developed a patented system that displays the measured seconds and the fractions of a second concentrically. The watch features two sweep chronograph hands, each of them driven by an independent mechanism. The hand that performs a complete revolution per minute shows the stopped seconds in the traditional manner. The other hand (lacquered red in the new Ref. 5470P-001) performs one revolution per 12 seconds, i.e. five times faster than an ordinary chronograph hand and sweeps across 12 sectors subdivided into tenths. In this way, the user can immediately read the elapsed seconds guided by the pearl markers and then, on the outer railway track scale, read the number of elapsed tenths of a second departing from the last red marker. The minutes of the short-time measurement are displayed by the instantaneous 30-minute counter on the subsidiary dial at 3 o’clock.

Given so much simplicity in use, the patented system’s heart is a true treasure chest of ingenious solutions that remain hidden from sight within the movement. solutions that remain hidden from sight within the movement. As usual, Patek Philippe raised the bar and specified that the new caliber should meet ambitious requirements in every respect. The watch should not only be able to measure and display tenths of a second but also retain this precision during a 30-minute run of the chronograph. Additionally, Caliber CH 29-535 PS 1/10 had to be built as compactly as possible while retaining the diameter of the base caliber (29.6mm) and allowing only a slight increase in thickness (from 5.35mm to 6.96mm) – despite the two chronograph mechanisms and a total of 396 parts. As a true accomplishment in miniaturization, this new movement is even shorter than split-seconds Caliber CHR 29-535 PS (7.1mm).

Energy control and high precision
The Patek Philippe Grand Complication thus created is as complex as a tourbillon, a minute repeater or a split-seconds chronograph. For the frequency of 5 Hz and the integration of an additional chronograph mechanism with a high-speed hand, the new caliber CH 29-535 PS 1/10 requires considerably more energy. To master and limit this energy appetite, the engineers had to intervene at all nooks and crannies of the movement. And of course, the term “precision” dominated the entire development of the movement.

The challenge began with a single mainspring that was needed to provide energy for the whole movement. Patek Philippe reworked this component and enhanced its efficiency to preserve the amplitude of the balance spring as much as possible and to assure optimized rate stability. To increase the available energy and boost the power reserve, the diameter of the barrel arbor was reduced and the number of mainspring coils increased. A patented notch reduces the tension of the slipping spring during the winding process, thus eliminating the risk of damage due to the increased force.

A high-tech regulator mechanism
To handle the three challenges – efficiency, reliability, and rate accuracy – Patek Philippe decided to use its Oscillomax ensemble that had been developed by the “Patek Philippe Advanced Research” department. This high-tech regulator mechanism presented in 2011 was granted 17 patents and has three innovative components that rely on all advantages of the Silinvar technology – based on a derivative of silicon with extraordinary physical and mechanical characteristics (lightweight, rugged, antimagnetic, etc.). The ensemble operates with a Spiromax balance spring with a patented terminal curve and an inner boss, a Pulsomax escapement consisting of a lever and escape wheel with extensively reworked geometries as well as a Gyromax balance in Silinvar with gold inlays. This is the first time since the launch of the perpetual calendar “Patek Philippe Advanced Research Ref. 5550P“ (2011) that Patek Philippe has added the Oscillomax ensemble in its current collection. But this option plays a decisive role for the exceptional performance of the new Caliber CH 29-535 PS 1/10 movement. And it enables the high rate accuracy with a maximum deviation of -3 /+2 seconds per day specified by the Patek Philippe Seal – despite the clearly higher energy consumption of the movement.

Fluid and perfectly synchronized hand movements
Another big challenge arose during the development of Caliber CH 29-535 PS 1/10 regarding the quality of the display, particularly of the tenths of a second. The two chronograph displays must be perfectly synchronized. Despite the high speed of rotation, the tenth-of-a-second hand must move fluidly without jumps or vibrations. Here, too, the Manufacture’s engineers developed and implemented innovative solutions.

The mechanism for displaying the tenths of a second receives its energy via a driving wheel from the fourth wheel of the base movement. Patek Philippe designed the driving wheel in a novel two-part arrangement: the upper wheel with flexible spokes, the lower one with rigid spokes. Thanks to this patented anti-backlash principle that is both compact and energy-saving, the teeth of the driving wheel exert an elastic force on the clutch wheel, eliminating any risk of hand vibration.

As soon as the chronograph is started, the tenth-of-a-second driving wheel (operating at one revolution per minute) engages with the tenth-of-a-second pinion that performs one revolution in 12 seconds (turning five times faster). To enable this “acceleration”, Patek Philippe provided the tenth-of-a-second pinion with microtoothing: 136 teeth on a pinion diameter of 1.469mm and with a tooth height of 30 μm. The pretensioning force exerted by the clutch wheel on the pinion suppresses tooth backlash. Many individual measures maximize the accuracy of the display.

A proven shock absorber
Another indispensable measure needed for a user-centric solution relates to the shock absorber. The new Caliber CH 29-535 PS 1/10 had to handle all requirements and risks to which it would be exposed in daily use. For this purpose, Patek Philippe developed two patented mechanisms. One of them is a shock absorber hook that would secure the clutch rocker during the entire short-time measurement process. The second one uses the “unbalances” (centres of gravity, not to be confused with centres of rotation) of components of the mechanism for the tenths-of-a-second chronograph. In the event of a shock, the acceleration values of the components exposed to it are compensated instead of being cumulated. The result is that all components remain in the desired positions, eliminating any impact on the correct function of the watch.

A monopusher chronograph
In a last notable feature, the chronograph has a single pusher at 2 o’clock that successively executes the start, stop, and reset commands. This monopusher arrangement recalls classic chronographs and will delight aficionados of technical timepieces. In addition to the patented special features of Caliber CH 29-535 PS 1/10, the new watch embodies the seamless pairing of tradition and innovation that constitutes the core of the Patek philosophy.

The sapphire-crystal case back (interchangeable with the solid platinum back delivered with the watch) affords a spectacular view of Caliber CH 29-535 PS 1/10 with its filigreed components and the elaborately executed finishes (bridges with chamfered and polished edges, Geneva striping, etc.). The engraved, gilt inscriptions “Oscillomax 5 Hz” and “GyromaxSi” on the bridges refer to the innovative movement components.

A resolutely sporty style
A movement dedicated entirely to performance and short-time measurements needs to be well protected, so Patek Philippe created an inimitably sporty exterior. To house this concentrated blend of technical prowess, the Manufacture chose platinum, the most precious metal but also the most difficult one to machine. The gently rounded case has the same design as the manually wound Ref. 5370 Split Seconds Chronograph launched in 2015. As a special feature, it has a concave bezel that forms a perfect transition to the slightly domed sapphire crystal. The case flanks are slightly recessed and satin-finished, the lugs are subtly curved and feature decorative cabochons at the ends of the spring bars. Like all of Patek Philippe’s platinum models, Ref. 5470P-001 is adorned with a flawless brilliant-cut diamond between the lugs at 6 o’clock.

The elegant blue of the dial harmonizes exceptionally well with the shimmering reflections of the platinum case, at the same time offering a perfect contrast for the crisp legibility of the individual displays. The chronograph seconds are indicated with a sandblasted and rhodium-plated steel hand on a minutes scale with small gold pearls. The tenths of a second are displayed with a slender hand in Silinvar. Because it is so lightweight, the high-tech material saves energy but has the rigidity needed to withstand the shock that occurs when the chronograph is abruptly stopped. Thanks to a new patented process for decorating the Silinvar hand, in this case lacquered red, and a second patent concerning the attachment of the pipe to the Silinvar hand by brazing, Patek Philippe succeeded for the first time in using the promising material for external features of a watch. The red color of the hand is also echoed on the markers of the railway-track scale for reading tenths of a second. As long as the chronograph is not operating, the red and grey chronograph hands are superposed and look like a single hand. Once a short-time measurement has been started with the pusher at 2 o’clock, it launches its fascinating ballet with two separate rotation speeds. The instantaneous 30-minute counter at 3 o’clock and the small seconds at 9 o’clock have crisp railway-track scales to improve the legibility of the respective information.

The new 5470P-001 is worn on a navy blue calfskin strap with an embossed fabric pattern and red decorative seams in perfect harmony with the colours of the dial. Its fold-over clasp in platinum ensures comfort and safety on the wrist.