Backlight Unit Micromirror Array for HUD Illumination

Solution Overview

Problem

Conventional backlight units for head-up display devices require a large number of parts and a significant size due to the need for multiple light sources and a parallel light generating unit to illuminate the entire liquid crystal panel, leading to inefficiencies in luminance and part reduction.

Innovation Solution

A backlight unit incorporating a light source, a light collecting member, a micromirror array with a concave reflecting surface, and a diffusion plate, where the micromirrors are arranged in a specific pattern with convex or concave curved surfaces to efficiently direct light to a liquid crystal display element, reducing the need for multiple light sources and optical components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If multiple light sources and a parallel light generating unit are used to illuminate the entire liquid crystal panel, then the illumination coverage is improved, but the number of parts and device size increase

Engineering Contradiction:

Improveillumination coverageVSAvoidnumber of parts

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The liquid crystal panel surface is divided into multiple regions, with each micromirror in the micromirror array responsible for illuminating a specific region. This segmentation allows a single light source to effectively cover the entire panel by directing light to different areas through multiple micromirrors positioned at different angles and locations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution transitions from using multiple light sources arranged in one dimension to using a single light source with micromirrors arranged in two dimensions (different positions and angles). This dimensional change in the optical path allows one light source to achieve the illumination coverage that would otherwise require multiple sources.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Illumination intensity

If multiple light sources and a parallel light generating unit are used to illuminate the entire liquid crystal panel, then the illumination coverage is improved, but the device size increases

Engineering Contradiction:

Improveillumination coverageVSAvoiddevice size

Core Design Contradiction:

Illumination intensityVSVolume of moving object

Solution Approach 1:

The liquid crystal panel surface is divided into multiple regions, with each micromirror in the micromirror array responsible for illuminating a specific region. This segmentation allows a single light source to effectively cover the entire panel by directing light to different areas through multiple micromirrors positioned at different angles and locations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution transitions from using multiple light sources arranged in one dimension to using a single light source with micromirrors arranged in two dimensions (different positions and angles). This dimensional change in the optical path allows one light source to achieve the illumination coverage that would otherwise require multiple sources.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If conventional optical components are used, then the optical path is established, but the luminance unevenness occurs due to the need for parallel light conversion and multiple light sources

Engineering Contradiction:

Improveoptical path establishmentVSAvoidluminance unevenness

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

Each micromirror is designed with specific local optical properties (curved or flat surfaces at different angles) tailored to its position in the array. This local optimization ensures that light from a single source is evenly distributed across different regions of the liquid crystal panel, preventing luminance unevenness while maintaining reliable optical paths.

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 allows for a reduction in the number of parts and size, improved light utilization efficiency, and reduced luminance unevenness by illuminating the entire liquid crystal panel with a single light source, while minimizing power consumption and optical system size.

Implementation Method 1

an optical member that includes a concave reflecting surface and reflects light incident from the light collecting member toward a light transmissive liquid crystal display element by the reflecting surface

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a diffusion plate that is arranged on an optical path between the optical member and the liquid crystal display element

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS10379398B2Backlight unit and head-up display device

Publication Date: 2019.08.13 YAZAKI CORP

AI summary

A backlight unit includes a light source, a light collecting member that collects light emitted from the light source, and a concave reflecting surface, and includes a micromirror array that reflects the light incident from the light collecting member toward a liquid crystal panel by the reflecting surface and a diffusion plate that is arranged on an optical path between the micromirror array and the liquid crystal panel. In the micromirror array, the reflecting surface includes the plurality of micromirrors. One or more groups of the plurality of micromirrors are arranged in the reflecting surface in an X direction and a Y direction. Each micromirror includes a convex or concave curved surface.