Laser-Induced Light Scattering for Concealing Defective Pixels
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Solution Overview
Problem
Organic EL display devices have low yield due to defective pixels, which are difficult to repair, especially those in a constantly non-lit state, leading to increased costs and reduced image quality.
Innovation Solution
A display device and method where external energy is selectively applied to a member on the light extraction side of defective pixels to impart a light scattering property, making the defective pixels inconspicuous by diffusing light from adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If high-voltage pulse or laser is applied to repair short-circuited pixels, then the short-circuited pixels are restored to normal, but constantly non-lit pixels cannot be repaired and remain conspicuous defects
Solution Approach 1:
The patent converts the harmful effect of constantly non-lit pixels by applying laser irradiation to create light scattering centers at defect locations. The laser energy transforms the dark, conspicuous defect into a light-scattering region that reflects ambient light, making the defect invisible. This converts the harmful darkness of non-lit pixels into a beneficial light-scattering property that masks the defect.
Solution Approach 2:
The patent changes the optical parameter of the pixel region by applying laser irradiation, which creates light scattering centers. This parameter change transforms the optical behavior from light transmission (making defects visible as dark spots) to light scattering (making defects invisible by reflecting light). The laser irradiation permanently alters the optical properties of the region containing constantly non-lit pixels.
2Ease of repair
If laser is used to cut current-supplying lines to change constantly lit pixels to constantly non-lit, then the constantly lit defect is concealed, but the pixel becomes a conspicuous constantly non-lit defect
Solution Approach 1:
The patent applies laser irradiation to convert constantly non-lit pixels (whether originally non-lit or converted from constantly lit) into light-scattering regions. This converts the harmful effect of visible dark spots into a beneficial light-scattering property that masks the defect by reflecting ambient light, making the previously conspicuous defect now invisible.
3Ease of repair
If preliminary storage capacitance or switching elements are added to prepare for expected defects, then defect repair capability is improved, but the number of producing steps increases and costs rise
Solution Approach 1:
The patent extracts the defect repair function from the pixel structure itself by using laser irradiation to create light scattering centers directly at defect locations. This eliminates the need for additional preliminary components such as storage capacitances or switching elements, simplifying the pixel structure and reducing production complexity while maintaining defect repair capability.
4Ease of repair
If preventive measures are taken for all pixels to guard against expected defects, then defect repair capability is improved, but pixel definition deteriorates and numerical aperture lowers
Solution Approach 1:
The patent applies laser irradiation locally only to regions containing defective pixels, creating light scattering centers precisely at defect locations. This localized approach preserves the optical quality and numerical aperture of normal pixels while providing defect repair capability only where needed, avoiding the degradation of pixel definition that would result from universal preventive measures.
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 conceals defective pixels, improving yield and reducing production costs by making them less noticeable, thus enhancing the quality and affordability of organic EL display devices.
Implementation Method 1
a member which is arranged on the light extraction side of a defective pixel, the defective pixel being in a constantly non-lit state, the member being imparted with a light scattering property by the selective application of external energy
Data Source
AI summary
A display device 10 including a supporting substrate 12, pixels arranged over the supporting substrate, and a member which is arranged on the light extraction side of a defective pixel 22b, the defective pixel being in a constantly non-lit state, the member being imparted with a light scattering property by the selective application of external energy. Preferably, disposed is a thermosensitive layer 24 which changes from a transparent state to a light scattering state when the layer is heated to a specified temperature or higher. An examination is performed for specifying the constantly non-lit defective pixel from among the pixels arranged over the supporting substrate. An external energy is selectively applied to at least one member arranged on the light extraction side of the defective pixel specified by the examination, thereby imparting the light scattering property to the member.