Touchpad Module Light Guide Plate Brightness Uniformity

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Solution Overview

Problem

Touchpad modules often suffer from issues like light leakage and uneven brightness due to light absorption by translucent ink layers and edge-related problems such as black bars, affecting appearance and user experience.

Innovation Solution

The touchpad module incorporates a light guide plate, circuit board, light source, reflective layer, thin film, touch substrate, cover, and a low light-transmission layer, with an air layer between the thin film and light-exit surface, and a light-shielding plate to prevent light energy loss and improve brightness and uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light-transmitting adhesive layer is used to attach the cover to the light guide plate, then the assembly is simple and lightweight, but light is absorbed by the translucent ink layer causing low brightness

Engineering Contradiction:

ImprovebrightnessVSAvoidlight absorption

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent removes the light-transmitting adhesive layer from between the light guide plate and cover, eliminating the source of light absorption. The cover is directly attached to the light guide plate, extracting the problematic adhesive layer from the optical path while maintaining structural assembly.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

An air layer is introduced as an intermediary between the light guide plate and cover. This air layer acts as an optical mediator with minimal light absorption properties, allowing light to pass through while maintaining the necessary structural separation and attachment.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Shape

If an edge-type backlight assembly is used, then the appearance is lighter and thinner, but light leakage and black bars appear at the edges

Engineering Contradiction:

Improvethin appearanceVSAvoidlight leakage

Core Design Contradiction:

ShapeVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potentially harmful light leakage at edges into a beneficial uniform light distribution. By optimizing the light guide plate structure and using a reflective layer at the bottom, stray light that would cause leakage is redirected to contribute to uniform brightness across the display area.

Inventive Principle:

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

Solution Approach 2:

Different regions of the light guide plate are given different optical properties. The light guide plate has specific refractive index variations and surface structures in different areas to control light propagation, with the reflective layer providing localized light redirection at the bottom surface to prevent edge darkening.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If the translucent ink layer is printed on the back of the glass cover, then the touch panel has display function, but brightness is reduced due to light absorption

Engineering Contradiction:

Improvedisplay functionVSAvoidbrightness

Core Design Contradiction:

Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The patent changes the optical parameters of the cover assembly by removing the light-transmitting adhesive layer and introducing an air layer. This parameter change reduces light absorption while maintaining the display function, as the air layer has superior light transmission properties compared to the adhesive material.

Inventive Principle:

Principle #35Parameter changes

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 enhances the total brightness and uniformity of the light emitted, reducing light leakage and edge issues, thereby improving the aesthetic appeal and user experience of the touchpad module.

Implementation Method 1

The light guide plate has a light-exit surface, a bottom surface, a light-entrance surface and a distant surface... The light is transmitted through the light guide plate in a direction away from the light source and emerges from the light-exit surface

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The reflective layer is disposed on one side of the bottom surface of the light guide plate and is located between the light guide plate and the base portion of the circuit board

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS11474632B1Touchpad module

Publication Date: 2022.10.18 CHICONY POWER TECH CO LTD

AI summary

A touchpad module including a light guide plate, a circuit board, a light source, a reflective layer, a thin film, a touch substrate, a cover, and a low light-transmission layer is provided. The light source is disposed on one side of the incident surface of the light guide plate. The thin film overlaps a light-exit surface, a distant surface, and a bottom surface of the light guide plate, and has a first end side and a second end side. The first end side is fixed to a side edge area of the light-exit surface. The second end side is fixed to the reflective layer. The cover is located on one side of the light-exit surface of the light guide plate. The thin film is located between the cover and the light guide plate. The low light-transmission layer is disposed on one side of the cover facing the light guide plate.