Nautical Chart Distance Measurement Using a Screen-Placed Ruler

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Solution Overview

Problem

Existing nautical chart display devices using touch operations for distance measurement are difficult for users accustomed to paper charts, as they require understanding complex touch-based calculations.

Innovation Solution

A nautical chart display device with a touch operation identifying module, tool identifying module, and tool displaying module that displays distance markers on the screen based on the position and orientation of a measurement tool, such as a ruler, allowing easy distance measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If touch operation is used for distance measurement on nautical chart, then measurement function is provided, but ease of operation deteriorates for users accustomed to paper charts

Engineering Contradiction:
Improvemeasurement functionVSAvoidease of operation
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent uses a physical ruler that visually copies the appearance of traditional paper chart rulers, allowing users familiar with paper charts to operate the electronic device intuitively without learning new touch gestures. The ruler's visual design replicates the familiar measurement tool from paper navigation.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The physical ruler acts as an intermediary between the user and the electronic touch screen. Instead of directly touching the screen with fingers, users place the ruler on the screen, and the system detects the ruler's position and orientation to perform measurements, bridging the gap between traditional paper chart methods and modern touch interfaces.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If scale calculation is required for distance measurement, then measurement precision is maintained, but device complexity increases

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system automatically performs scale calculations and distance computations without requiring user intervention. When a ruler is placed on the screen, the system detects the ruler's position, automatically calculates the corresponding real-world distance based on the chart scale, and displays the result, eliminating the need for users to manually perform scale conversions.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system pre-calculates and stores the relationship between ruler positions and real-world distances based on the chart scale. This preliminary preparation allows for rapid, accurate measurements without requiring complex real-time calculations during the measurement process itself.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If manual scale calculation is required, then measurement accuracy is achieved, but loss of time increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidloss of time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system automatically performs all scale calculations and distance computations without requiring user intervention. When a ruler is placed on the screen, the system detects the ruler's position, automatically calculates the corresponding real-world distance based on the chart scale, and displays the result, eliminating the need for users to manually perform scale conversions.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical calculation methods with automated electronic detection and computation. The touch screen detector automatically identifies the ruler's position and the processor performs calculations, substituting the manual mechanical process of aligning rulers and calculating scales with an automated electronic system that provides immediate results.

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

Data Source

PatentEP3709146B1Nautical chart display device, nautical chart display method, and nautical chart display program
Publication Date: 2026.04.08 FURUNO ELECTRIC CO LTD
  • EP3709146B1 patent drawingFigure 1
  • EP3709146B1 patent drawingFigure 2
  • EP3709146B1 patent drawingFigure 3

AI summary

The purpose is to provide a nautical chart display device which enables a measurement of a distance in a method easily understandable even for a user who is not used to a measurement of a distance by a touch operation. The nautical chart display device 20 includes a display unit 21, a touch operation identifying module 52, a tool identifying module 53, and a tool displaying module 54. The display unit 21 displays a nautical chart on a screen. The touch operation identifying module 52 identifies a touch operation to the screen. The tool identifying module 53 identifies a position and an orientation of a ruler placed on the screen. The tool displaying module 54 displays distance markers according to a scale of the nautical chart on the screen at the position where the ruler is placed, based on the position and the orientation identified by the tool identifying module 53.