MIP Photo Diode for Display Luminance Control
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Solution Overview
Problem
Conventional light emitting display devices with photo diodes (PDs) require multiple masks for manufacturing, increasing costs and complexity due to the use of both P-type and N-type impurities, leading to high power consumption and inefficient luminance control.
Innovation Solution
A light emitting display device with a simplified structure featuring a photo diode having a P-type doping region and an intrinsic region, where both are co-planar and electrically coupled, allowing for reduced mask usage and improved light sensitivity through a Metal-Intrinsic-P-type (MIP) structure, enabling efficient luminance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional PIN structure photo diode with both P-type and N-type impurities is used, then the photo diode can function properly, but multiple masks are required increasing manufacturing complexity and cost
Solution Approach 1:
The patent extracts and removes the N-type doped region from the conventional PIN structure, retaining only the P-type doped region and intrinsic region. This extraction eliminates the need for multiple masks while maintaining photo diode functionality through the simplified MIP structure.
Solution Approach 2:
The patent applies local quality by creating a specific P-type doped region with particular doping concentration (1E16 to 1E18 atoms/cm³) and thickness (50-200 nm) adjacent to the intrinsic region, optimizing the local properties to achieve both functionality and simplified manufacturing.
2Device complexity
If a conventional LED with constant luminance is used, then the LED structure is simple, but power consumption is high due to inability to control luminance according to ambient light
Solution Approach 1:
The patent implements feedback by using the photo diode to detect ambient light conditions and automatically adjusting the LED luminance accordingly. The controller receives signals from the photo diode and modulates the LED output, creating a closed-loop system that reduces power consumption while maintaining appropriate display visibility.
3Manufacturing precision
If multiple masks are used to form both photo diode and TFT, then proper device formation is achieved, but manufacturing cost and process time increase
Solution Approach 1:
The patent merges the photo diode formation process with the existing TFT manufacturing process by using the same P-type doping step for both devices. This consolidation reduces the total number of masks and process steps while maintaining the precision needed for proper device formation.
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 MIP structure reduces manufacturing complexity, lowers power consumption, and enhances light sensitivity, allowing for accurate measurement and control of ambient light, thereby improving display properties.
Implementation Method 1
The PD may convert light energy, e.g., light emitted from the LED or ambient light, into an electrical signal, e.g., electric current or voltage, by generating electrons or holes in accordance with an optical absorption
Implementation Method 2
The PD may convert light energy, e.g., light emitted from the LED or ambient light, into an electrical signal, e.g., electric current or voltage, by generating electrons or holes
Data Source
AI summary
A light emitting display device includes a light emitting diode and a thin film transistor on a substrate, the light emitting diode and thin film transistor being electrically coupled to each other, and a photo diode on the substrate, the photo diode including an intrinsic region and a P-type doping region coupled to each other.