Vehicle Head-Up Display Compact Optical Path Design

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Solution Overview

Problem

Existing head-up displays for vehicles are not compact enough in the forward and backward directions, requiring a solution to minimize their width and size while maintaining functionality.

Innovation Solution

A head-up display configuration that includes a display panel, a polarized light plate, a phase delay mirror, and a polarized light reflective mirror, where the phase delay mirror is larger than the other components and positioned to convert and reflect light in a zigzag pattern, allowing for a compact design by closely arranging the polarized light reflective mirror and phase delay mirror, and optimizing the placement of a polarized light plate, polarized light reflective mirror, and phase delay mirror within a holder.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the head up display uses a conventional optical path configuration with multiple mirrors and optical components, then the display functionality is achieved, but the width of the head up display in the forward and backward direction increases

Engineering Contradiction:
Improvewidth of head up displayVSAvoidoptical path configuration
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent employs a zigzag optical path configuration where light reflects between mirrors positioned at angles to each other, effectively using three-dimensional spatial arrangement to fold the optical path. This allows the optical components to be compactly arranged in the lateral direction while maintaining the required optical path length in the forward-backward direction, thereby reducing the overall width without compromising display functionality

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent integrates multiple optical components (display panel, polarized light plate, phase delay mirror, polarized light reflective mirror, and reflective mirror) into a compact assembly where components are nested or closely arranged. The holder structure accommodates these components in a space-efficient manner, with the polarized light plate and mirrors positioned in close proximity to each other, minimizing the overall footprint of the head-up display

Inventive Principle:
Principle #7Nested doll (Nesting)

2Use of energy by moving object

If the phase delay mirror is made larger than other components to optimize light reflection, then the light conversion efficiency is improved, but the overall size of the head up display increases

Engineering Contradiction:
Improvelight conversion efficiencyVSAvoidsize of head up display
Core Design Contradiction:
Use of energy by moving objectVSVolume of moving object

Solution Approach 1:

The patent applies different size requirements to different optical components based on their specific functions. The phase delay mirror is made larger than the polarized light plate and polarized light reflective mirror because it requires a larger surface area to effectively convert and reflect light with the necessary phase delay. However, this size differentiation is optimized so that only the phase delay mirror is larger, while other components maintain compact dimensions, achieving local optimization of light conversion efficiency without proportionally increasing the overall display size

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 configuration forms an optical path that minimizes the width of the head-up display in the forward and backward directions, making it more compact and efficient, while enhancing assembly and maintainability by mounting components in a holder within a main body.

Implementation Method 1

a polarized light plate configured to convert the image light emitted from the display panel into linearly polarized light

Methodology Applied
Scientific EffectPolarization: Polarisation

Implementation Method 2

the phase delay mirror is further configured to convert a phase of the light received from the polarized light plate into a first converted phase, and to reflect the first converted phase to the polarized light reflective mirror

Methodology Applied
Scientific EffectPhase delay:

Implementation Method 3

the reflective mirror is configured to reflect the second converted phase onto a windshield of a vehicle

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3414618B1Head up display for vehicle
Publication Date: 2021.08.04 LG ELECTRONICS INC
  • EP3414618B1 patent drawingFigure 1
  • EP3414618B1 patent drawingFigure 2
  • EP3414618B1 patent drawingFigure 3

AI summary

A head up display for a vehicle according to an embodiment includes a display panel configured to emit an image light; a polarized light plate configured to make the image light emitted from the display linearly polarized; a reflective mirror configured to reflect the image light onto a windshield of a vehicle; a polarized light reflective mirror configured to be disposed to face the reflective mirror; and a phase delay mirror configured to convert a phase of the light inputted from the polarized light plate and reflect the converted phase to the polarized light reflective mirror, and to convert a phase of the light reflected from the polarized light reflective mirror and reflect the converted phase to the polarized light reflective mirror, thereby minimizing a width in the forward and backward direction.