Chronograph Mechanism Backlash Compensation for Thousandth-Second Precision
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Solution Overview
Problem
Conventional mechanical chronograph mechanisms face challenges in achieving high precision time measurement beyond one hundredth of a second while maintaining a sufficient power reserve and avoiding premature wear of components, due to high oscillator frequencies and complex designs that complicate user readability.
Innovation Solution
A chronograph mechanism featuring a control device and gear train with a second counter mobile and an additional mobile for precision fractions of a second, utilizing a backlash wheel set to drive an indicator for second fractions, allowing measurement and display of times with precision to a thousandth of a second without the need for high-frequency oscillators, and incorporating a catch-up mobile to prevent errors and extend power reserve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-frequency oscillator (500 Hz) is used to achieve thousandth-of-a-second precision, then measurement precision is improved, but power reserve is reduced to only 150 seconds and component wear increases
Solution Approach 1:
The chronograph mechanism is segmented into two independent timing systems: a high-frequency system (500 Hz) for thousandth-of-a-second precision and a conventional low-frequency balance wheel (2.5 Hz) for power storage. The high-frequency system uses a specialized wheel with 500 teeth and corresponding counters, while the low-frequency system maintains the traditional balance spring regulator. This segmentation allows each subsystem to operate at its optimal frequency without compromising the other.
Solution Approach 2:
A frequency conversion mechanism acts as an intermediary between the low-frequency balance wheel and the high-frequency measurement display. The balance wheel's slow oscillations are mechanically amplified through a series of gear trains and leverages to drive the high-speed rotation of the thousandth-of-a-second indicator wheel, enabling high-precision measurement without requiring a high-frequency oscillator.
2Measurement precision
If a high-frequency oscillator (500 Hz) is used to achieve thousandth-of-a-second precision, then measurement precision is improved, but component wear increases prematurely
Solution Approach 1:
The chronograph mechanism is segmented into two independent timing systems: a high-frequency system (500 Hz) for thousandth-of-a-second precision and a conventional low-frequency balance wheel (2.5 Hz) for power storage. The high-frequency system uses a specialized wheel with 500 teeth and corresponding counters, while the low-frequency system maintains the traditional balance spring regulator. This segmentation allows each subsystem to operate at its optimal frequency without compromising the other.
Solution Approach 2:
A frequency conversion mechanism acts as an intermediary between the low-frequency balance wheel and the high-frequency measurement display. The balance wheel's slow oscillations are mechanically amplified through a series of gear trains and leverages to drive the high-speed rotation of the thousandth-of-a-second indicator wheel, enabling high-precision measurement without requiring a high-frequency oscillator.
3Measurement precision
If a complex high-frequency oscillator system is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges two chronograph systems into one unified mechanism: the conventional seconds/minutes counter and the new thousandth-of-a-second counter. Both systems share common components such as the mainspring barrel, control lever, and reset mechanism. The high-frequency wheel is integrated into the existing chronograph gear train, and its indicator hand is superimposed on the same dial, creating a compact multi-functional device.
Solution Approach 2:
The balance wheel serves multiple functions: it acts as the power source for the entire chronograph mechanism, drives the conventional seconds counter, and simultaneously powers the high-frequency thousandth-of-a-second display through frequency conversion. This multi-functionality reduces the need for separate power sources and simplifies the overall structure.
4Measurement precision
If a non-decimal counter display is used, then measurement precision is improved, but ease of operation is reduced due to difficult readability
Solution Approach 1:
The dial display is designed with local quality differentiation: the main seconds counter uses conventional decimal markings (0-60) for easy readability, while the thousandth-of-a-second counter uses specialized markings (0-1000 or 0-100) positioned in a separate sector. Each display area has its own optimal scale and notation, allowing users to read both precision levels without confusion.
Solution Approach 2:
The thousandth-of-a-second display is positioned in a different spatial dimension on the dial, typically as a smaller sub-dial or a radial scale perpendicular to the main seconds hand. This dimensional separation allows the high-precision display to coexist with the conventional display without interfering with readability, as users can naturally focus on different parts of the dial depending on their measurement needs.
Data Source
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AI summary
The mechanism has a chronograph gear train comprising a seconds-counter mobile (1) and a mobile (3) with first precision corresponding to first fraction e.g. tenth, of a second. The gear train has an additional mobile (5) with second precision corresponding to second fraction e.g. hundredth, of second, where the additional mobile is driven by the mobile for the first fraction of second via a backlash compensating mobile (4). An indicator, actuated by the additional mobile, indicates the second fraction of second of measured duration, smaller than the first fraction of second.