Microlens Array Sheet for Wearable Display Pixel Grid

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Solution Overview

Problem

Head-mounted displays with high-curvature lenses for wide viewing angles suffer from pixel grid visibility, leading to degraded image quality and increased back-focus adjustment sensitivity, narrowing the manufacturing yield.

Innovation Solution

Incorporating a microlens array sheet in the optical path between the display panel and eyepiece to act as an optical lowpass filter, blurring the pixel grid and reducing back-focus adjustment sensitivity by diffusing light and adjusting the optical lowpass filter effect based on pixel size and array pattern.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a lens high in curvature is used to display a video image having a wide viewing angle, then the viewing angle is improved, but the pixels become visually enlarged and pixel grids stand out, degrading image quality

Engineering Contradiction:
Improveviewing angleVSAvoidimage quality
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent introduces a microlens array sheet as an intermediary component between the display panel and the eyepiece lens. This microlens array acts as a mediator that optically processes the light from each pixel, preventing the direct visualization of pixel grids while maintaining the wide viewing angle capability provided by the high-curvature eyepiece lens.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the optical parameters by introducing the microlens array sheet with specific focal length and lens pitch parameters. This modification alters the light propagation characteristics, effectively reducing the visual impact of pixel enlargement caused by the high-curvature eyepiece lens while preserving the wide viewing angle.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If a lens high in magnification is used, then the viewing angle is improved, but the back-focus adjustment sensitivity becomes high, narrowing the adjustment margin and reducing manufacturing yield

Engineering Contradiction:
Improveviewing angleVSAvoidback-focus adjustment margin
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The microlens array sheet serves as an intermediary optical element that decouples the back-focus adjustment sensitivity from the eyepiece lens magnification. By introducing this intermediate component, the system gains an additional degree of freedom in optical path control, effectively reducing the sensitivity of back-focus adjustment while maintaining high magnification for wide viewing angles.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the optical system parameters by adding the microlens array sheet with controllable focal length and position. This parameter change effectively reduces the back-focus adjustment sensitivity, widening the acceptable adjustment margin and improving manufacturing yield while preserving the high magnification capability.

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

Prevents pixel grid visibility, maintains image quality with wide viewing angles, and mitigates back-focus adjustment sensitivity, enhancing manufacturing yield and image quality.

Implementation Method 1

Incorporating a microlens array sheet in the optical path between the display panel and eyepiece to act as an optical lowpass filter, blurring the pixel grid and reducing back-focus adjustment sensitivity by diffusing light

Methodology Applied
Scientific EffectLight diffusion: Diffusion

Data Source

PatentEP3249444B1Wearable display device and image display method
Publication Date: 2022.06.22 SONY GROUP CORP
  • EP3249444B1 patent drawingFigure 1
  • EP3249444B1 patent drawingFigure 2(a)~2(b)
  • EP3249444B1 patent drawingFigure 3(a)~3(b)

AI summary

With an image display apparatus, such as a head-mounted display, the eyes 220 of a user observe an image displayed on a display panel 200 through an eyepiece 210 in an enlarged manner. A microlens array sheet 230 that is one example of an optical element functioning as an optical lowpass filter is inserted in an optical path running from the display panel 200 to the eyepiece 210.