Auxiliary Reflecting Surface for Display Illumination Uniformity

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Solution Overview

Problem

The existing display illumination structures suffer from low luminance in areas closer to the light source due to the critical angle reflection, limiting the placement range and design flexibility of the gauge portion.

Innovation Solution

An auxiliary reflecting surface is introduced on the housing, closer to the light source, to reflect non-incident and leaked light towards the low-luminance areas, utilizing a concavely recessed light collecting portion to enhance illumination efficiency and uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the interior reflecting bent portion is configured with critical angle reflection to guide light to the distal end, then light reaches the distal end of the horizontally extending portion, but low-luminance poorly illuminated portions are produced near the light source

Engineering Contradiction:
ImproveluminanceVSAvoidplacement range of gauge portion
Core Design Contradiction:
Illumination intensityVSEase of operation

Solution Approach 1:

The reflecting surface is segmented into two distinct portions: the interior reflecting bent portion using critical angle reflection to guide light to the distal end, and the auxiliary reflecting surface using diffuse reflection to illuminate areas near the light source. This segmentation allows each portion to perform its specific function optimally without interfering with the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The auxiliary reflecting surface acts as an intermediary element that captures light not incident on the incident portion and light leaking from the light guiding member, then redirects this light toward low-luminance portions. This intermediary component bridges the gap between the light source and areas that would otherwise remain poorly illuminated.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the gauge portion is extended closer to the light source to increase placement range, then design freedom increases, but low-luminance poorly illuminated portions are produced due to critical angle reflection limitations

Engineering Contradiction:
Improvedesign freedomVSAvoidluminance
Core Design Contradiction:
Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

Different reflecting surfaces are applied to different locations: the interior reflecting bent portion with critical angle reflection for the distal end area, and the auxiliary reflecting surface with diffuse reflection for areas near the light source. This local differentiation ensures optimal illumination quality in each specific region while allowing the gauge portion to be freely positioned.

Inventive Principle:
Principle #3Local quality

3Productivity

If light is totally reflected at critical angle to reach distal end, then light guidance efficiency is improved, but light cannot reach near the light source causing illumination non-uniformity

Engineering Contradiction:
Improvelight guidance efficiencyVSAvoidillumination uniformity
Core Design Contradiction:
ProductivityVSIllumination intensity

Solution Approach 1:

Two different reflection mechanisms are merged into a single light guiding member: critical angle reflection in the interior reflecting bent portion for efficient light guidance to the distal end, and diffuse reflection in the auxiliary reflecting surface for illuminating areas near the light source. This combination maintains high light guidance efficiency while achieving uniform illumination across the entire gauge portion.

Inventive Principle:
Principle #5Merging (Combining)

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 configuration improves luminance in low-luminance areas, allowing for uniform illumination and expanded placement range of the gauge portion, thereby increasing design freedom.

Implementation Method 1

a main reflecting surface 27, provided on an inner surface of the housing 26, which reflects light L that exits from the light guiding member 25 so as to be returned to the light guiding member 25

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

an auxiliary reflecting surface 42, provided on an inner surface of the housing 26 in a position which lies closer to the light source 24, which reflects light L1 that is not incident on the incident portion 28 and light L2 that leaks from a halfway portion of the light guiding member 25 towards a low-luminance poorly illuminated portion 14

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

the auxiliary reflecting surface 42 has a concavely recessed light collecting portion 42a which collects light towards the low-luminance poorly illuminated portion 14

Methodology Applied
Scientific EffectLight collection through concave geometry: Focusing

Implementation Method 4

the interior reflecting bent portion 31 which reflects the light L that enters from the incident portion 28 towards the horizontally extending portion 29

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2666659B1Display illumination structure
Publication Date: 2017.12.13 CALSONIC KANSEI CORP
  • EP2666659B1 patent drawingFigure 1
  • EP2666659B1 patent drawingFigure 2
  • EP2666659B1 patent drawingFigure 3

AI summary

A display illumination structure includes: a display including a gauge portion; a light source; a light guiding member including an incident portion, a horizontally extending portion configured to guide the light emanating from the light source along the gauge portion, and an interior reflecting bent portion configured to reflect the light that enters from the incident portion towards the horizontally extending portion; and a housing including a main reflecting surface configured to reflect light that exits from the light guiding member so as to be returned to the light guiding member, and an auxiliary reflecting surface configured to reflect light that is not incident on the incident portion and light that leaks from a halfway portion of the light guiding member towards a low-luminance poorly illuminated portion being formed in a position on the gauge portion which lies closer to the light source.