Windshield HUD Virtual Image Alignment to Reduce Double Images

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Solution Overview

Problem

Existing heads-up display (HUD) systems face challenges in maintaining the visibility of virtual images without causing double images or fatigue, due to parallax issues when viewed by drivers, and often require complex device configurations to mitigate these issues.

Innovation Solution

The HUD device employs a laser scan method with a concave mirror and optical scanning unit to project virtual images onto a windshield, ensuring a parallax angle of less than 1 degree between the virtual and real images, thereby preventing double images and simplifying the device configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If a virtual image is projected onto the windshield using conventional HUD methods, then information can be displayed to the driver, but parallax causes double images and deteriorates visibility

Engineering Contradiction:
Improvevisibility of virtual imageVSAvoidparallax-induced double images
Core Design Contradiction:
Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent changes the optical parameters of the HUD system by introducing a concave mirror with specific focal length and curvature. This modifies the light path and image formation characteristics to reduce parallax effects. The concave mirror focuses light rays to create a virtual image at a specific distance, adjusting the convergence angle to minimize the difference between virtual and real object viewing angles, thereby reducing double images and improving visibility.

Inventive Principle:
Principle #35Parameter changes

2Loss of information

If complex optical systems are used to correct parallax issues, then visibility can be improved, but device complexity increases

Engineering Contradiction:
Improvevisibility of virtual imageVSAvoiddevice configuration complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple optical components into a single concave mirror element. The concave mirror simultaneously performs light focusing, image formation, and parallax correction that would traditionally require separate optical components. This integration simplifies the overall device configuration while maintaining the ability to produce clear virtual images with reduced parallax effects.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a concave mirror with a curved reflective surface to correct optical aberrations and control light paths. The spherical curvature of the mirror enables precise control over light ray convergence and virtual image positioning, achieving parallax reduction without requiring complex multi-element optical systems. The curved surface geometry allows for effective focal length adjustment and image quality optimization.

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

This approach effectively maintains the visibility of virtual images while preventing double images and fatigue, and reduces the complexity of the device configuration, ensuring clear and comfortable viewing for drivers.

Implementation Method 1

an optical scanning unit configured to scan the image light beam

Methodology Applied
Scientific EffectOptical scanning:

Implementation Method 2

a concave mirror configured to lead the scanned image light beam

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

The HUD device employs a laser scan method

Methodology Applied
Scientific EffectLaser: Laser

Data Source

PatentEP3350646B1Information display apparatus, information provision system, moving object device, information display method, and recording medium
Publication Date: 2024.01.17 RICOH CO LTD
  • EP3350646B1 patent drawingFigure 1
  • EP3350646B1 patent drawingFigure 2~3
  • EP3350646B1 patent drawingFigure 4

AI summary

An information display apparatus emits an image forming light beam to a transmissive reflection member and makes a virtual image visible through the reflection member. The information display apparatus is configured to display the virtual image so that a difference between a convergence angle when viewing the virtual image through the reflection member and a convergence angle when viewing a real object through the reflection member is less than or equal to 1 degree.