Electronic Timepiece Compass Calibration with Inclination Sensor
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Solution Overview
Problem
Existing electronic timepieces with compass functions face challenges in accurately calculating the north azimuth when the display surface is inclined relative to the horizontal plane, due to complex and burdensome calibration operations required to account for offset magnetic fields, which can fail if not performed correctly.
Innovation Solution
An electronic timepiece equipped with a three-axis magnetic sensor and an inclination sensor, featuring a detection axis calibration unit that performs separate calibration processes for horizontal and vertical components, allowing for mode switching between two measurement modes to facilitate accurate azimuth calculation based on detected values from both sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration processing is performed to acquire offset magnetic fields in both horizontal and vertical directions, then measurement precision is improved, but device complexity and ease of operation deteriorate due to complex calibration operations
Solution Approach 1:
The calibration process is segmented into two independent calibration modes: first calibration processing for horizontal offset magnetic fields and second calibration processing for vertical offset magnetic fields. This segmentation allows users to perform only the necessary calibration based on their specific needs, reducing operational complexity while maintaining measurement precision when full calibration is performed.
Solution Approach 2:
The system dynamically switches between different measurement modes (first measurement mode using only horizontal components, second measurement mode using both horizontal and vertical components) based on whether second calibration processing has been completed. This dynamic adaptation allows the device to provide accurate azimuth calculations without requiring users to always perform complex full calibration procedures.
2Measurement precision
If second calibration processing is performed to acquire vertical offset magnetic field, then measurement precision is improved, but loss of time increases due to repeated calibration operations
Solution Approach 1:
The system allows for partial calibration (first calibration processing only) when full calibration (including second calibration processing) is not necessary. Users can perform only the horizontal calibration for typical horizontal usage scenarios, saving time while maintaining sufficient accuracy. The option for complete calibration remains available when higher precision is needed.
Solution Approach 2:
The first calibration processing for horizontal offset magnetic fields is performed as a preliminary step that is sufficient for most common usage scenarios. This preliminary calibration saves users from performing the more time-consuming second calibration processing unless specifically needed for inclined surface measurements.
3Ease of operation
If only horizontal offset magnetic field is acquired through first calibration processing, then ease of operation is improved, but measurement precision deteriorates when display surface is inclined
Solution Approach 1:
The measurement mode dynamically adapts based on calibration status and inclination detection. When second calibration processing is completed, the system switches to the second measurement mode that utilizes vertical magnetic field components to compensate for inclination effects, maintaining precision even when the display surface is inclined.
4Ease of operation
If calibration operation is made simple by omitting second calibration processing, then ease of operation is improved, but reliability deteriorates due to calibration failure when inclination compensation is needed
Solution Approach 1:
The calibration is segmented into optional first calibration processing (horizontal only) and optional second calibration processing (vertical component). This segmentation improves reliability by allowing users to perform second calibration processing when inclined surface measurements are anticipated, ensuring calibration success for the specific usage scenario.
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
Simplifies the calibration process by allowing users to select between two measurement modes, improving user convenience and ensuring accurate azimuth calculations even when the device is not held horizontally, reducing the need for repeated calibration attempts.
Implementation Method 1
a three-axis magnetic sensor configured to detect a magnetic field in two axial directions orthogonal to each other in a plane parallel with the dial and a direction along an axis orthogonal to the plane
Implementation Method 2
an inclination sensor configured to detect an inclination of the case main body
Data Source
AI summary
An electronic timepiece includes a detection axis calibration unit configured to execute first calibration processing of calibrating an axial direction and second calibration processing of calibrating a direction along a third detection axis, the second calibrating processing being executed after first calibration processing, a mode setting unit configured to set a first measurement mode when second calibration processing is not completed after completion of the first calibration processing, and set a second measurement mode when the second calibration processing is completed, a first azimuth calculation unit configured to calculate an azimuth, based on detected values of a three-axis magnetic sensor in two axial directions, when the first measurement mode is set, and a second azimuth calculation unit configured to calculate an azimuth, based on detected values of the three-axis magnetic sensor in three axial directions and a detected value of a inclination sensor, when the second measurement mode is set.