Quartz Watch Clock Frequency Testing Method

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Solution Overview

Problem

Current methods for testing the operation and frequency of electronic watches, such as quartz watches, are inefficient and require lengthy testing periods, often necessitating expensive and complex equipment, and do not allow for accelerated testing or configuration in an accelerated test mode.

Innovation Solution

A method involving a three-step process to test the clock frequency of an electronic watch, including configuring the clock module in a test mode, measuring the clock frequency without inhibition, acquiring the current inhibition value, and calculating the watch's frequency, which can be completed in approximately 6 seconds while maintaining good precision, and a time base device capable of implementing this method.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the inhibition period is increased to improve the accuracy of timing frequency measurement, then the measurement accuracy is improved, but the maximum error between two time measurements increases proportionally and the test time cannot be determined solely based on a number of successive inhibition periods

Engineering Contradiction:
Improvetiming frequency measurement accuracyVSAvoidtest time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the testing process into two distinct phases: a first measurement phase without inhibition to obtain baseline timing data, and a second measurement phase with inhibition to obtain corrected timing data. This segmentation allows the system to separate the effects of inhibition from the measurement process, enabling accurate frequency measurement without requiring excessively long inhibition periods. The segmented approach resolves the contradiction by providing sufficient measurement data points quickly while maintaining accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary measurements without inhibition before applying inhibition during the second measurement phase. This preliminary action establishes a baseline for timing frequency that can be used to calculate corrections later. By performing the preliminary measurement first, the system can then apply inhibition in a controlled manner and use the difference between the two measurement phases to determine the actual frequency, thereby achieving accurate measurement without requiring prolonged inhibition periods.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If traditional testing methods are used to determine watch accuracy, then measurement precision is achieved, but the testing time is lengthy (approximately four hours) and expensive equipment is required

Engineering Contradiction:
Improvewatch accuracy determinationVSAvoidtesting time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces complex mechanical timing systems with electronic frequency measurement techniques. Instead of using mechanical oscillators and lengthy physical timing processes, the system uses electronic counters, inhibitors, and digital signal processing to measure frequency directly. This substitution of electronic methods for mechanical methods dramatically reduces the testing time from four hours to a fraction of a second while maintaining measurement precision through electronic accuracy rather than mechanical precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from direct mechanical timing duration to frequency count over a standardized period. By measuring the number of oscillations or pulses within a known time frame and calculating frequency from this count, the system can determine watch accuracy much faster than traditional methods. This parameter change from time-based mechanical measurement to frequency-based electronic measurement is what enables the drastic reduction in testing time while maintaining precision.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If the reference frequency oscillator is produced with a slightly higher frequency to allow for inhibition correction, then the manufacturing process is simplified, but the accuracy of the time base requires careful calibration and verification over extended periods

Engineering Contradiction:
Improveoscillator productionVSAvoidtime base accuracy verification
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism where the system measures the actual frequency during operation and compares it against the expected frequency. Based on this comparison, the system calculates correction values that can be applied to compensate for frequency deviations. This feedback loop allows the manufacturing process to be simplified by producing oscillators with slightly higher frequency, while still achieving high manufacturing precision through automated frequency verification and correction in the final testing phase.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly accelerates frequency measurement in production, eliminating the need for costly test equipment and reducing testing time from hours to seconds while maintaining high accuracy, allowing for precise thermal correction and efficient production.

Implementation Method 1

a clock module with a 32 kHz quartz crystal

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3168695B1Method for testing the performance of a quartz watch
Publication Date: 2021.03.10 ETA SA MFG HORLOGERE SUISSE
  • EP3168695B1 patent drawingFigure 1
  • EP3168695B1 patent drawingFigure 2~3

AI summary

The method for testing the accuracy of an electronic watch with a time-base device (1) comprises three main steps for testing on test equipment. The time-base device includes at least one clock module (2) with a resonator (3) connected to an oscillator of an electronic circuit (4), which is followed by a divider circuit, controlled by an inhibition circuit, and which provides a divided clock signal for a motor. In the first step, a measurement of the frequency of a reference signal from the oscillator is performed in at least one measurement period without inhibition. A second step is provided to acquire the current inhibition value for inhibiting a certain number of clock pulses in a subsequent inhibition period and to determine the inhibition value. Finally, a third step is provided to calculate the corresponding rate of the watch.