S-Shaped Optical Waveguide Core for Position Sensor Light Leakage

Solution Overview

Problem

Existing optical waveguides and position sensors face issues with precise sensing of pressed positions due to light leakage in S-shaped core portions, leading to inconsistent light intensity reception, which affects the accuracy of position sensing and proper light propagation in optical circuit boards.

Innovation Solution

The optical waveguide is designed with a partially S-shaped core structure, where the width of the exit and entrance of the second curved portion is smaller than the upstream core portion, reducing light leakage by ensuring the incident angle exceeds the critical angle, thus enhancing light reflection and reducing propagation loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the core is formed in an S-shape to route light between opposite ends of the optical waveguide, then light propagation is achieved, but light leakage occurs at the curved portions leading to inconsistent light intensity reception and reduced sensing precision

Engineering Contradiction:

Improvelight propagationVSAvoidposition sensing precision

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies local quality by making the core width variable specifically at the curved portions of the S-shaped path, while maintaining uniform width in straight sections. The core width is reduced to a first width at the first curved portion and a second width at the second curved portion, creating localized structural modifications that address light leakage only where needed without affecting the overall waveguide structure or other functional regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the geometric parameter of core width at specific locations along the S-shaped path. By adjusting the core width parameter at the curved portions (making it smaller than in straight sections), the patent modifies the optical properties locally to control light reflection and prevent leakage, thereby resolving the contradiction between achieving light propagation and maintaining sensing precision.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If the core width is reduced at curved portions to reduce light leakage, then light propagation loss is reduced, but the core becomes more difficult to manufacture with precise dimensions

Engineering Contradiction:

Improvelight propagation lossVSAvoidcore dimension precision

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent applies local quality by making the core width variable specifically at the curved portions of the S-shaped path, while maintaining uniform width in straight sections. The core width is reduced to a first width at the first curved portion and a second width at the second curved portion, creating localized structural modifications that address light leakage only where needed without affecting the overall waveguide structure or other functional regions.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If the core width is made uniform throughout the optical waveguide, then manufacturing is simplified, but light leakage occurs at S-shaped curved portions reducing light intensity consistency

Engineering Contradiction:

Improvecore fabricationVSAvoidlight intensity consistency

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent applies local quality by making the core width variable specifically at the curved portions of the S-shaped path, while maintaining uniform width in straight sections. The core width is reduced to a first width at the first curved portion and a second width at the second curved portion, creating localized structural modifications that address light leakage only where needed without affecting the overall waveguide structure or other functional regions.

Inventive Principle:

Principle #3Local quality

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 design improves the precision of position sensing by equalizing light intensity reception and reducing light propagation loss, ensuring reliable operation of electronic devices with optical circuit boards.

Implementation Method 1

reducing light leakage by ensuring the incident angle exceeds the critical angle, thus enhancing light reflection

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS10288807B2Optical waveguide having core partially formed in S-shape, and position sensor and optical circuit board including the same

Publication Date: 2019.05.14 NITTO DENKO CORP

AI summary

Provided are an optical waveguide capable of propagating light, and a position sensor and an optical circuit board including the same. The optical waveguide includes cores each partially formed in an S-shape. The S-shaped portion includes a first curved portion upstream as seen in the direction of light propagation, and a second curved portion downstream as seen in the direction of light propagation and curved in a direction opposite to the first curved portion. The first curved portion and the second curved portion are connected to each other via a straight portion having a length in the range of from 0 mm to 30 mm. One of the width of the exit of the first curved portion and the width of the entrance of the second curved portion is smaller than the width of a core portion upstream of the S-shaped portion.