Dual Reflecting Layer Light Guide Module for Optical Detection

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Solution Overview

Problem

Conventional edge-type light guide plates in backlight modules suffer from high signal interference, limiting their application in optical detection devices for high sensitivity and accuracy.

Innovation Solution

A light guide module with a light guide plate and optical reflecting structures, comprising a first reflecting layer with low absorption and a second reflecting layer with higher reflection rate, positioned on the bottom and above the first layer respectively, to interfere with total internal reflection and direct the beam outwards, reducing interference and enhancing detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single reflecting layer is used on the bottom of the light guide plate, then the structure is simple, but the optical detection accuracy is low due to high signal interference

Engineering Contradiction:

Improvereflecting structureVSAvoiddetection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The reflecting layer is divided into two separate layers: a first reflecting layer with low reflection rate and a second reflecting layer with high reflection rate. This segmentation allows each layer to perform its specific function independently, reducing signal interference and improving detection accuracy while maintaining reasonable structural complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the reflecting structure are assigned different reflection rates. The first reflecting layer has a low reflection rate to reduce interference signals, while the second reflecting layer has a high reflection rate to maintain light guide functionality. This local differentiation optimizes both detection accuracy and light guidance.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If the first reflecting layer has high reflection rate, then more light is reflected outward, but signal interference increases and detection accuracy decreases

Engineering Contradiction:

Improvelight reflection intensityVSAvoiddetection accuracy

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The reflection rate parameter is optimized differently for the two layers. The first reflecting layer uses a low reflection rate (0-30%) to minimize interference, while the second reflecting layer uses a high reflection rate (70-95%) to ensure sufficient light output. This parameter differentiation resolves the contradiction between light intensity and detection accuracy.

Inventive Principle:

Principle #35Parameter changes

3Length of stationary object

If the second reflecting layer is positioned close to the first reflecting layer, then the structure is compact, but the beam absorption and reflection efficiency is reduced

Engineering Contradiction:

Improvedistance between layersVSAvoidbeam energy loss

Core Design Contradiction:

Length of stationary objectVSLoss of energy

Solution Approach 1:

The first reflecting layer is designed with partial absorption characteristics (not complete absorption), allowing it to absorb some beam energy while still permitting sufficient light to reach the second reflecting layer. This partial action approach balances structural compactness with energy efficiency.

Inventive Principle:

Principle #16Partial or excessive action

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 solution effectively reduces signal interference, allowing for accurate detection of external objects moving over the light guide plate, improving detection accuracy and preventing the optical detector from capturing unwanted reflections from the reflecting structures.

Implementation Method 1

The first reflecting layer is disposed on a bottom surface of the light guide plate, and the beam is partly absorbed by the first reflecting layer

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

The second reflecting layer is formed above the first reflecting layer, and the beam is reflected outward the light emitting surface via the second reflecting layer

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 3

A beam emitted from the lighting unit can enter the light guide plate through its side surface, and is transmitted to a far end of the light guide plate by total internal reflection

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS8890056B2Light guide module having dual reflecting layer wherein light beam being partly absorbed by the first reflecting layer and optical detection device thereof

Publication Date: 2014.11.18 PIXART IMAGING INC

AI summary

A light guide module is disclosed in the present invention. The light guide module includes a light guide plate, and an optical reflecting structure disposed on a bottom of the light guide plate. A beam is transmitted into the light guide plate through its side surface. Total internal reflection characters of the light guide plate is interfered by the optical reflecting structure, so that the beam can emit out of the light guide plate through a light emitting surface of the light guide plate. The optical reflecting structure includes a first reflecting layer disposed on the bottom, and a second reflecting layer formed above the first reflecting layer. The beam is absorbed by the first reflecting layer. The beam is reflected out of the light emitting surface via the second reflecting layer, and the second reflecting layer is between the first reflecting layer and the light guide plate.