Reflective Electrode Light Sensor Isolation in OLED Displays
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Solution Overview
Problem
Organic light emitting display devices used in portable devices face operational reliability issues due to internal light generated by the organic light emitting diode, which can cause electrical current generation in transistors and lead to malfunctions.
Innovation Solution
The device incorporates a substrate with a pixel region and a non-pixel region, featuring a reflective first electrode covering most of the substrate except for the pixel area and light sensor region, an organic light emitting layer on the exposed electrode, and a second electrode, along with a black matrix to prevent internal light from reaching sensitive elements, ensuring external light is only measured by the light sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light sensor is disposed inside the portable display device to sense external light intensity, then the brightness control function is improved, but internal light from the organic light emitting diode may enter transistors and cause electrical current generation leading to malfunctions
Solution Approach 1:
The device is divided into distinct functional regions: a pixel region containing transistors and OLEDs, and a non-pixel region containing the light sensor. This spatial segmentation prevents internal light from reaching sensitive transistor components while allowing the light sensor to function independently for external light measurement.
Solution Approach 2:
The light sensor is extracted from the pixel region and placed in a separate non-pixel region. This extraction removes the light sensor from the area where internal light is generated, eliminating the harmful interaction between internal light and the light sensor while maintaining the brightness control function.
2Illumination intensity
If the first electrode area is made larger than the organic light emitting layer area to reflect light, then light reflection capability is improved, but the device structure becomes more complex
Solution Approach 1:
The first electrode serves multiple functions: it acts as a reflective surface to redirect light, provides electrical connection, and defines the pixel structure. By making the electrode area larger than the organic light emitting layer, it simultaneously performs light reflection and structural definition without requiring additional components.
Solution Approach 2:
The first electrode is configured with different areas in different regions: a larger area for light reflection and a smaller exposed region for organic light emitting layer formation. This local variation in electrode area optimizes both light reflection efficiency and device structure without uniform complexity throughout.
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 stabilizes the operation of pixels by reflecting and blocking internal light, preventing it from entering transistors and other sensitive elements, thus enhancing the reliability and precision of external light measurement.
Implementation Method 1
a first electrode formed of a reflective material reflecting light and disposed on the entire surface of the insulating film except for a region between the pixels and except for a region over the light sensor
Implementation Method 2
an organic light emitting diode receiving an electric current from the pixel circuit to emit light
Data Source
AI summary
An organic light emitting display device. The organic light emitting display device includes a substrate having a pixel region in which pixels are formed and a non-pixel region in which a light sensor is formed, an insulating film formed on the substrate, a first electrode formed on the insulating film and formed of a reflective material reflecting light, the first electrode being formed on the entire surface of the insulating film except for a region between the pixels and a region over the light sensor, a pixel defining film exposing a region of the first electrode and formed on the insulating film, an organic light emitting layer formed on the exposed region of the first electrode, and a second electrode formed on the organic light emitting layer. The first electrode is formed to have a greater area than that of the organic light emitting layer.