Satellite Radio-Controlled Watch Time Zone Determination

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Solution Overview

Problem

Satellite radio-controlled watches face challenges in determining time zones due to complex time zone boundaries that do not always align with lines of longitude, requiring large storage capacity and increased computing load, which is costly and power-consuming.

Innovation Solution

The use of lines of longitude or latitude as reference lines to define time difference divisions, with intersection points corresponding to specific time differences, allowing for more accurate and efficient storage and computation of time zone information, including variable-length data storage to prevent overlap and reduce storage capacity requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If data is obtained by meshing the ground surface into sufficiently small portions with a time zone assigned to each, then determination accuracy of time zone is improved, but storage capacity requirement increases hugely

Engineering Contradiction:
Improvetime zone determination accuracyVSAvoidstorage capacity
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The ground surface is divided into mesh portions (latitude/longitude grids), and time zone data is stored only for portions containing time zone boundaries. This segmentation approach stores data sparsely rather than densely, reducing storage capacity while maintaining determination accuracy through targeted boundary data.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different storage strategies are applied to different regions: portions with time zone boundaries store detailed time zone assignment data, while portions without boundaries store minimal or no data. This local quality differentiation optimizes storage capacity by avoiding redundant data storage in regions where boundary information is unnecessary.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If data is obtained by meshing the ground surface into sufficiently small portions, then determination accuracy of time zone is improved, but computing load increases

Engineering Contradiction:
Improvetime zone determination accuracyVSAvoidcomputing load
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The computing process is segmented into two stages: first determining which mesh portion the current position falls into, then checking only that specific portion's boundary data. This segmentation of the computation process reduces the overall computing load compared to checking all mesh portions or using complex continuous boundary evaluation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention extracts and stores only the essential boundary information (time zone boundaries intersecting with mesh portions) rather than storing complete time zone assignments for all portions. This extraction of critical data reduces both storage requirements and the computing complexity needed for time zone determination.

Inventive Principle:
Principle #2Taking out (Extraction)

3Quantity of substance

If block data is used to reduce data volume, then storage capacity is reduced, but time zone determination accuracy may be compromised

Engineering Contradiction:
Improvedata volumeVSAvoidtime zone determination accuracy
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The invention uses mesh portions (defined by latitude and longitude lines) as the segmentation unit, which provides a standardized and precise framework for locating time zone boundaries. This segmentation approach maintains determination accuracy while enabling efficient data organization and storage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the parameter representation from storing complete time zone assignments for all regions to storing only boundary intersection data with specific precision requirements. This parameter change allows for reduced data volume while maintaining sufficient accuracy for time zone determination.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3239789B1Satellite radio-controlled watch
Publication Date: 2021.05.26 CITIZEN WATCH CO LTD
  • EP3239789B1 patent drawingFigure 1
  • EP3239789B1 patent drawingFigure 2
  • EP3239789B1 patent drawingFigure 3

AI summary

A satellite radio-controlled watch, including a receiving unit (20) for receiving a satellite radio wave containing time information and position information; a storage unit (32) for storing intersection point information indicating a position of an intersection point between a reference line along a great circle orthogonal to a specific great circle on the earth or a reference line along the specific great circle on the earth or a circle parallel to the great circle and a time zone boundary, and time difference division information on a wedge-shaped or belt-shaped area that is adjacent to the reference line and to which the intersection point belongs, and a time zone determination unit (31a) for determining a time zone, based on the position information, the intersection point information, and the time difference division information.