AR-HUD Prism Light Path Layout for Crosstalk-Free Multi-Focal Imaging

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Solution Overview

Problem

Current augmented reality head-up displays (AR-HUDs) require multiple picture generation units, leading to large size and high costs, and there is a need to improve display effect and reduce size and costs.

Innovation Solution

A display apparatus with a projection module, deflection reflection component, and prism group that splits imaging light into multiple paths, allowing different images to be projected onto different focal planes using a simple light path structure without precision machinery control, thereby reducing the risk of image crosstalk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a liquid crystal display is used in a vehicle, then information can be displayed to the driver, but glare from sunlight or headlights may cause discomfort or accidents

Engineering Contradiction:
Improvedisplay brightnessVSAvoidglare from sunlight or headlights
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a dynamic approach by using a variable neutral density filter that can change its light attenuation properties in real-time. The filter transitions between different states (first and second neutral density) based on environmental conditions such as whether the vehicle is in daytime or nighttime mode, allowing the display to adapt its brightness characteristics dynamically to prevent glare while maintaining visibility

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the optical parameters of the display system by implementing a dual-state neutral density filter that modifies the transmittance characteristics. In daytime mode, the filter provides higher light attenuation to prevent glare from sunlight, while in nighttime mode, it provides lower attenuation to maintain display visibility in dark environments, thus adjusting the key parameter of light transmittance based on operating conditions

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If a variable neutral density filter is added to control glare, then glare prevention is improved, but the device complexity increases

Engineering Contradiction:
Improveglare preventionVSAvoidfilter mechanism complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts the glare control function from the main display structure by implementing a separate, dedicated variable neutral density filter layer. This filter is positioned between the liquid crystal display and the external environment, isolating the glare control mechanism from the display's internal complexity while maintaining a relatively simple overall structure through functional separation

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If the display shows high-contrast images to improve visibility, then image quality is improved, but power consumption increases

Engineering Contradiction:
Improveimage visibilityVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent introduces a variable neutral density filter as an intermediary element between the light source and the display medium. This intermediary optimizes the light conditions before they reach the liquid crystal display, enabling the system to achieve good image visibility with reduced power consumption by pre-conditioning the light rather than relying solely on high-power display elements

Inventive Principle:
Principle #24Intermediary (Mediator)

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 achieves a compact size and improved imaging reliability by enabling multiple images to be displayed simultaneously without image crosstalk, reducing the need for multiple picture generation units and lowering costs.

Implementation Method 1

a liquid crystal panel for displaying images in response to video signals applied thereto

Methodology Applied
Scientific EffectLiquid crystal effect: Liquid Crystals

Implementation Method 2

a variable neutral density filter having a light transmittance that is variable between a first light transmittance and a second light transmittance

Methodology Applied
Scientific EffectNeutral density filtration: Absorption (EM radiation)

Data Source

PatentEP4435491B1Display device and vehicle
Publication Date: 2026.05.06 YINWANG INTELLIGENT TECHNOLOGIES CO LTD
  • EP4435491B1 patent drawingFigure 1~2
  • EP4435491B1 patent drawingFigure 3
  • EP4435491B1 patent drawingFigure 4~5

AI summary

A display apparatus and a transportation means are provided. A prism group (103, 803, 1003) is used to change optical paths of different imaging sub-light. A light path structure is simple, a reuse rate of a device is high, and an image basically has no crosstalk. The display apparatus includes: a projection module (101, 801, 1001), a deflection reflection component (102, 802, 1002), and a prism group (103, 803, 1003). The projection module (101, 801, 1001) is configured to project a first path of imaging light to the deflection reflection component (102, 802, 1002). The deflection reflection component (102, 802, 1002) is configured to: reflect the first path of imaging light to generate at least two paths of imaging sub-light, and respectively reflect the at least two paths of imaging sub-light to the prism group (103, 803, 1003) at at least two angles. The prism group (103, 803, 1003) is configured to: enable the at least two paths of imaging sub-light to propagate through different paths, and emit the at least two paths of imaging sub-light.