Organic EL Display Luminance Control Without External Sensors
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Solution Overview
Problem
Organic electroluminescence display devices face challenges with miniaturization, weight saving, and layout freedom due to the need for external luminance sensors, and varying luminance detection results across large display areas, leading to inadequate light emission intensity control.
Innovation Solution
A display method that detects drive current changes in light-emitting pixels to switch between standard and high luminance images, eliminating the need for external sensors by using the light-emitting devices themselves for luminance control, ensuring consistent and appropriate light emission intensity adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external luminance sensor is provided to measure outside light, then light emission intensity control can be achieved, but miniaturization and weight saving are hindered and layout freedom is restricted
Solution Approach 1:
The patent merges the luminance sensor function with the existing organic EL display elements. The display elements themselves are used to detect outside light by monitoring changes in their drive current, eliminating the need for separate external sensors. This integration maintains light emission control capability while reducing device complexity and improving miniaturization.
Solution Approach 2:
The organic EL display elements perform dual functions: they serve as both the light emitting components for display and as the luminance sensors for detecting outside light. By making the display elements multi-functional, the patent eliminates the need for dedicated external sensors, thereby achieving miniaturization and weight saving without sacrificing control capability.
2Ease of manufacture
If a luminance sensor is constructed of organic EL element and fabricated at the same time, then external attachment is eliminated, but miniaturization and weight saving are still hindered
Solution Approach 1:
The patent extracts the luminance sensing function from the overall system and assigns it to the existing organic EL display elements. Instead of adding sensor components during fabrication, the display elements themselves are utilized for sensing by monitoring their electrical characteristics, thereby eliminating the need for additional sensor structures and maintaining ease of manufacture.
Solution Approach 2:
The organic EL display elements serve themselves by using their own electrical characteristics to detect outside light. The drive current changes in the display elements themselves provide the sensing signal, eliminating the need for separate sensor fabrication and reducing device complexity while maintaining integrated manufacturing.
3Illumination intensity
If drive current detection is used to detect outside light, then visibility is improved in bright places, but power consumption increases due to continuous current monitoring
Solution Approach 1:
The patent implements periodic sampling of the drive current to detect outside light conditions, rather than continuous monitoring. The control unit periodically measures the drive current of the organic EL elements and adjusts light emission intensity based on these periodic measurements, thereby maintaining visibility in bright places while reducing power consumption compared to continuous monitoring.
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 enhances visibility by maintaining high contrast and allowing miniaturization and weight savings in display devices, while ensuring accurate light emission control without external sensors, even in large display areas.
Implementation Method 1
an organic electroluminescence element (hereinafter, referred to as 'organic EL element')
Implementation Method 2
when light with a wavelength corresponding to its energy gap enters, light excitation is occurred, whereby an electromotive force is generated in the respective light emitting elements
Data Source
AI summary
A display method and a display device capable of performing light emission control without the need for an external light sensor are provided. The display device uses the display pixel to detect the external light. A panel drive current that is a sum of drive currents flowing into the red, green and blue pixels is detected. The panel drive current and a set current value that has been previously set are compared with each other. When the panel drive current is equal to or higher than the set current in a standard luminance display mode, the standard luminance display mode is switched to a high luminance display mode. When the panel drive current is lower than the set current value, the high luminance display mode is switched to the standard luminance display mode.