Organic EL Lighting for Reflective LCD Contrast
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Solution Overview
Problem
Reflective liquid crystal display devices struggle to maintain high contrast and brightness in both bright and dark environments due to inefficiencies in light utilization and leakage, particularly when using front lights, which degrade display quality.
Innovation Solution
A display device with a lighting portion integrated on a reflective liquid crystal display, utilizing an organic electroluminescent element with a transparent anode layer, organic layer, and cathode layer to emit light downwards, minimizing light leakage and enhancing contrast by using a light shield layer and optimizing the positional relationship between the lighting portion and pixel electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a front light is provided in the reflective LCD to realize a display in the dark environment, then the display can be made in dark environments, but light leaks from the transparent acrylic plate to reach the eyes of the viewer, causing a problem of degrading the contrast of a LCD display
Solution Approach 1:
The patent extracts the light source (light emitting element) from the traditional front light position and relocates it to the back surface of the liquid crystal display panel. This extraction eliminates the light leakage problem that occurred when light sources were positioned in front of the display, as the light now travels through the liquid crystal layer and exits through the front surface without leaking from the sides.
Solution Approach 2:
The patent inverts the traditional lighting arrangement by placing the light source at the back instead of the front. In conventional reflective LCDs with front lights, light enters from the front and reflects off the liquid crystal. This patent reverses the path by having light enter from the back, pass through the liquid crystal layer, and exit through the front, thereby eliminating side leakage and improving contrast.
2Use of energy by moving object
If a transparent acrylic plate with grooves is used to refract light toward the reflective LCD, then light can be directed to the display surface, but a small amount of light leaks in the direction to the viewer, degrading display contrast
Solution Approach 1:
The patent removes the transparent acrylic plate with grooves from the optical path entirely. Instead of using this refraction method that caused light leakage toward the viewer, the invention directly positions the light emitting element on the back surface, allowing light to pass straight through the liquid crystal layer without requiring refraction or redirection elements that leak light.
3Use of energy by moving object
If the anode layer is made of transparent electrode material with high light transmittance, then light can pass through efficiently, but light leakage occurs that reaches the viewer's eyes
Solution Approach 1:
The patent inverts the light path direction so that light travels from the back surface through the liquid crystal layer to the front surface. By making the anode layer on the back surface transparent, light can efficiently enter the liquid crystal layer without being blocked, while the liquid crystal layer itself acts as the controlling element that prevents light leakage to the viewer.
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 solution enables a bright and high-contrast liquid crystal display in various environments by minimizing light leakage and optimizing light distribution, thereby improving display efficiency and reducing interference fringes.
Implementation Method 1
an organic electroluminescent element disposed on a front surface of the first substrate including an anode layer made of a transparent electrode material and having a predetermined pattern, an organic layer covering the anode layer, and a cathode layer having a pattern superposed on the anode layer with the organic layer interposed therebetween
Implementation Method 2
a third substrate formed with a reflective pixel electrode receiving light emitted by the organic electroluminescent element in each of the pixels
Data Source
AI summary
A lighting portion is attached to a reflective liquid crystal display portion. A first transparent substrate and a second transparent substrate made of a glass substrate etc. are attached to each other with a sealing layer coated on those peripheral portions therebetween. The back surface of the first transparent substrate is attached to the reflective liquid crystal display portion, and an organic EL element is formed on the front surface of the first transparent substrate. The organic EL element is sealed in a space surrounded by the first transparent substrate, the second transparent substrate, and the sealing layer. The organic EL element is formed in a region corresponding to a pixel region of the reflective liquid crystal display portion. A desiccant layer is formed on the front surface of the second transparent substrate.