Pointer Light Entrance Shaft Annular Rib Stray Light Control

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Solution Overview

Problem

Conventional light emitting pointer devices experience luminance unevenness due to stray light caused by the refraction of light at the boundary between the rotation shaft and the fit recess, leading to inefficient light distribution at the light emitting face.

Innovation Solution

A light emitting pointer device design featuring a coaxial configuration with an annular rib that covers the corner of the light entrance shaft, having a radius of curvature greater than the corner, to prevent stray light and ensure even luminance, comprising a light source, a light guide member, a pointer body with a light entrance shaft, a main pointer portion, a sub-pointer portion, and a light control space, and a holding member with specific structural features to manage light reflection and emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the rotation shaft is fitted into the fit recess of the pointer, then the pointer can rotate, but light is refracted at the boundary face between the rotation shaft and the fit recess causing stray light and luminance unevenness

Engineering Contradiction:

Improverotation capabilityVSAvoidluminance uniformity

Core Design Contradiction:

Ease of operationVSIllumination intensity

Solution Approach 1:

The invention extracts and removes the harmful refraction interface by making the rotation shaft and pointer shaft coaxial with their end faces facing each other, eliminating the boundary face between rotation shaft and fit recess that causes light refraction and stray light

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces an air layer as an intermediary medium between the rotation shaft end face and the pointer shaft end face, preventing direct contact and eliminating the refraction boundary while still allowing rotational movement

Inventive Principle:

Principle #24Intermediary (Mediator)

2Illumination intensity

If the rotation shaft end face faces the pointer shaft end face in a coaxial configuration, then refraction at the fit recess boundary is eliminated, but light may incident on the corner of the pointer shaft and travel in unintended directions becoming stray light

Engineering Contradiction:

Improveluminance uniformityVSAvoidstray light from corner

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The invention converts the potentially harmful corner of the pointer shaft into a beneficial feature by rounding it with a specific radius of curvature (R1), transforming what would be a light-trapping sharp edge into a light-guiding curved surface that directs light properly

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention changes the geometric parameter of the pointer shaft corner from a sharp edge to a rounded corner with a specific radius of curvature (R1), and modifies the annular rib face from flat to tapered with a larger radius of curvature to control light incidence angles

Inventive Principle:

Principle #35Parameter changes

3Object-generated harmful factors

If a flat annular rib face is used to cover the corner of the light entrance shaft, then light entry from the corner is blocked, but it is difficult to effectively cover the corner

Engineering Contradiction:

Improvecorner light entry preventionVSAvoidcorner covering effectiveness

Core Design Contradiction:

Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The invention applies curvature to the annular rib face by making it tapered with a radius of curvature (R2) greater than the pointer shaft corner radius (R1), creating a curved covering surface that effectively envelops the rounded corner and prevents light entry

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

The design effectively reduces stray light and luminance unevenness by ensuring light is directed towards the intended emission areas, providing a more uniform and balanced light distribution at the light emitting face.

Implementation Method 1

the light is refracted at a boundary face between the rotation shaft and the fit recess

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

light from the light source that has entered the pointer is totally reflected inside the pointer and is emitted from a surface (a light emitting face) of the pointer

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS11105661B2Light emitting pointer device

Publication Date: 2021.08.31 YAZAKI CORP

AI summary

A light emitting pointer device which can reduce luminance unevenness at a light emitting face is provided. An annular rib is provided between a first holding portion holding an emission shaft and a second holding portion holding a light entrance shaft and the annular rib thereby covers a corner of the light entrance shaft. As a result, the light is not likely to enter a pointer body from the corner of the light entrance shaft, thereby reducing stray light and reducing luminance unevenness. An upper face of the annular rib on the light entrance shaft side has a radius of curvature that is greater than a radius of curvature of the corner of the light entrance shaft and is tapered, thus the corner can be easily covered with a space between the light entrance shaft and the annular rib.