Transparent OLED Display with PDLC Light Scattering Control
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Solution Overview
Problem
Transparent organic light emitting display devices suffer from image distortion and degraded brightness and color due to light scattering and external light interference, as gaps between thin film transistor patterns are similar in size to visible light wavelengths, causing light to scatter and mixing with displayed images.
Innovation Solution
Incorporation of a polymer dispersed liquid crystal (PDLC) device between thin film transistors and a passivation layer, with electrodes forming an electric field to control light transmission, allowing for voltage-adjusted light scattering reduction and external light management, separating pixel regions from transmitting regions to minimize distortion and enhance image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent thin film transistors and transparent organic light emitting devices are used to create a transparent display device, then the device can transmit external light and reduce weight and thickness, but gaps between patterns cause light scattering and image distortion
Solution Approach 1:
A PDLC layer is introduced as an intermediary component between the transparent TFTs and the external environment. This layer acts as a mediator that can dynamically control light transmission, blocking scattered light when needed while maintaining transparency when not in use, thus resolving the contradiction between transparency and image distortion
Solution Approach 2:
The display device incorporates a dynamic light control mechanism through the PDLC layer that can switch between transparent and opaque states based on applied voltage. This dynamic adjustment allows the device to adapt to different viewing conditions, maintaining transparency when required while preventing image distortion during operation
2Weight of moving object
If the display device is made transparent with narrow gaps between patterns, then weight and thickness are reduced, but light scattering occurs because gap widths are comparable to visible light wavelengths
Solution Approach 1:
The PDLC layer serves as an intermediary that compensates for the light scattering caused by narrow gaps. By controlling the optical properties of this intermediate layer, the device can maintain its lightweight and thin structure while eliminating the harmful light scattering effect
3Illumination intensity
If external light is allowed to transmit through the transparent display device, then transparency is maintained, but image quality is degraded due to mixing of displayed light and external light
Solution Approach 1:
The PDLC layer provides dynamic control over external light transmission. When voltage is applied, the layer transitions to an opaque state, blocking external light and preventing mixing with displayed images. When voltage is removed, it returns to transparent state, allowing external light to pass through. This dynamic switching resolves the contradiction between maintaining transparency and preserving image 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
The PDLC device effectively reduces light scattering, allowing for clear and undistorted external image transmission while maintaining high contrast and brightness, enabling a stable and transparent display with adjustable external light transmission.
Implementation Method 1
voltages of different polarities are applied to the first electrode and the second electrode, respectively, to form an electric field
Implementation Method 2
a PDLC layer having liquid crystal dispersed in polymer matrix
Implementation Method 3
an organic emission layer disposed between the pixel electrodes and the opposite electrode and configured to emit light
Data Source
AI summary
An organic light emitting display device includes a substrate having a transmitting region interposed between pixel regions; thin film transistors on a first surface of the substrate; a passivation layer covering the thin film transistors; pixel electrodes on the passivation layer; an opposite electrode disposed to face the pixel electrodes; an organic emission layer between the pixel electrodes and the opposite electrode; a polymer dispersed liquid crystal (PDLC) device disposed such that the thin film transistors are between the PDLC device and the passivation layer, the PDLC device having: a first electrode; a second electrode; and a PDLC layer in which liquid crystal is dispersed in polymer matrix. Distortion of images transmitted through the organic light emitting display device is prevented by restricting scattering of the transmitted light, the transmission of the external light may be adjusted simply, and degradation of the brightness and color coordinate reproduction may be prevented.