Light Emitting Element Resonator Spectrum Shift
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Solution Overview
Problem
Light emitting elements with a resonator structure exhibit unacceptable luminance variations in the front direction due to manufacturing errors that affect the resonator optical path length, particularly in small display devices like mobile terminals and personal computers, where uniformity is crucial.
Innovation Solution
The solution involves setting the peak wavelength of the resonator output spectrum between the peak wavelength of the inner light emission spectrum and the relative luminous efficiency spectrum, with specific materials and film thickness adjustments to minimize luminance variations, ensuring the resonator output spectrum's peak wavelength is positioned to reduce luminance changes caused by deviations in the resonator optical path length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a resonator structure is used to enhance light emission directivity and filter characteristics, then luminance in the front direction is increased, but luminance variations occur due to manufacturing errors in resonator optical path length
Solution Approach 1:
The patent applies parameter changes by adjusting the peak wavelength of the resonator output spectrum relative to the inner light emission spectrum. Specifically, it sets the resonator output spectrum peak wavelength to be shifted by +10nm for red, +4nm for green, and -10nm for blue wavelengths. This parameter adjustment optimizes the resonance characteristics to reduce sensitivity to optical path length variations caused by manufacturing errors, thereby suppressing luminance variations while maintaining high front-direction luminance.
2Reliability
If the peak wavelength of multiple interference spectrum is matched to inner light emission spectrum, then color purity is improved, but luminance variations occur in small displays due to resonator optical path length deviations
Solution Approach 1:
The patent deliberately changes the wavelength parameter by shifting the resonator output spectrum peak wavelength away from the inner light emission spectrum peak wavelength. The specific shift amounts (+10nm for red, +4nm for green, -10nm for blue) are optimized to reduce the sensitivity of luminance to optical path length variations, thereby maintaining color purity while reducing luminance variations in small display applications.
3Adaptability or versatility
If resonator structure with specific filter characteristics is used, then viewing angle characteristics are improved, but luminance nonuniformity occurs in front direction for small displays
Solution Approach 1:
The patent adjusts the resonator output spectrum peak wavelength parameter to be shifted relative to the inner light emission spectrum. This parameter change optimizes the balance between viewing angle characteristics and front-direction luminance uniformity. By setting specific shift amounts for different colors (red: +10nm, green: +4nm, blue: -10nm), the patent achieves acceptable luminance uniformity in the front direction while maintaining the beneficial viewing angle characteristics of the resonator structure.
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 suppresses luminance variations in the front direction, maintaining acceptable color purity and image quality even with deviations in film thickness, thereby improving manufacturing yield and reducing costs.
Implementation Method 1
one of the upper electrode and the lower electrode is formed of a total reflection mirror and the other is formed of a semi-transmitting mirror allowing transmission of some of wavelengths, thereby resonating light emitted by the light emission layer
Implementation Method 2
Electroluminescence (EL) elements utilizing a substance which emits light by itself through an EL phenomenon when a voltage is applied thereto
Implementation Method 3
one of the upper electrode and the lower electrode is formed of a total reflection mirror
Data Source
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AI summary
[PROBLEMS] To provide a technique capable of suppressing luminance variations in a light emitting element having a resonator structure and a display apparatus even when a film thickness deviates from a design value to increase or decrease a resonator optical path length, by way of example. [SOLVING MEANS] A light emitting element includes a resonator structure which has a first reflecting member, a second reflecting member, and a light emission layer placed between the first reflecting member and the second reflecting member, and part of light resonated between the first reflecting member and the second reflecting member is transmitted through the first reflecting member or the second reflecting member in the resonator structure. A wavelength at which a resonator output spectrum from the resonator structure has a maximum value is located between a wavelength at which an inner light emission spectrum of the light emission layer has a maximum value and a wavelength at which relative luminous efficiency has a maximum value.