OLED Backlight Segmentation for Parallel Color Activation
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Solution Overview
Problem
Existing color display devices with organic light-emitting diode (OLED) backlighting face limitations in accuracy of optical reproduction and complexity of implementation, particularly due to sequential power-up of RGB sources leading to switching losses and reduced luminous intensity.
Innovation Solution
A color display device with a multicolor backlighting unit using OLEDs and an electro-optical switching array, where the pixels and illuminating lines are aligned, and cylindrical lenses are used to form light beams with parallel edges, allowing simultaneous activation of all colors and precise control of light transmission through the use of optical separators and electrodes, eliminating the need for color filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If RGB light sources are superimposed and turned on sequentially, then the visible spectrum can be reproduced through retinal persistence, but switching losses increase and luminous intensity decreases
Solution Approach 1:
The backlighting unit is segmented into separate red, green, and blue light sources positioned at different locations rather than superimposed. Each light source is served by dedicated optical paths and control electrodes, allowing independent control and simultaneous operation without sequential switching, thereby eliminating switching losses and maintaining high luminous intensity.
Solution Approach 2:
The patent transitions from a temporal dimension approach (sequential activation) to a spatial dimension approach (parallel activation with separate light sources). By distributing RGB sources across different spatial positions and using corresponding optical modulators, the system achieves simultaneous illumination without the switching penalties of sequential operation.
2Illumination intensity
If cold cathode lighting tubes are used for backlighting, then white light can be produced, but additional optical filtering devices are required and implementation becomes complicated
Solution Approach 1:
Instead of using a single white light source requiring color filtering, the system segments the backlighting into separate red, green, and blue light sources. Each source is optically coupled to corresponding optical modulators, eliminating the need for additional optical filtering devices and simplifying the overall implementation while maintaining white light capability through combination of primary colors.
3Speed
If OLED layers are made very thin to reduce capacitance, then switching speed improves, but switching losses increase due to higher capacitances
Solution Approach 1:
The patent divides the OLED structure into separate red, green, and blue light-emitting layers, each with its own control electrode and optical path. This segmentation allows independent optimization of each layer's thickness and electrical characteristics, enabling thinner layers with lower capacitance that can be switched faster without the switching losses associated with thicker, higher-capacitance layers.
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 solution simplifies the implementation, enhances the accuracy of optical reproduction, and allows for easy adjustment of white balance by controlling the luminous intensities of base colors, reducing switching losses and improving luminous intensity while eliminating the need for additional color filters.
Implementation Method 1
a multicolour backlighting unit using organic light-emitting diodes (OLED)
Implementation Method 2
light sources produced by one or more light sources is/are optically switched
Implementation Method 3
a cylindrical lens is disposed along each illuminating line on the backlighting unit in order to form a light beam with substantially parallel edges
Implementation Method 4
an electro-optical array for the switching of the backlighting by pixels
Data Source
AI summary
The invention relates to a color display device with backlighting unit using organic light-emitting diodes and to a method of implementation. The color display device comprises, from rear to front towards an observer, a multicolor backlighting unit using organic light-emitting diodes and an electro-optical array for switching of the backlighting by pixels, the backlighting unit being a surface comprising a periodic pattern of a group of at least three adjacent illuminating lines of different base colors that are parallel to each other. According to the invention, the pixels of the switching array and the illuminating lines of the backlighting unit are substantially aligned in order that a given pixel allows the forward transmission of only the corresponding base color to be controlled and that a cylindrical lens is disposed along each illuminating line on the backlighting unit in order to form a light beam with substantially parallel edges directed towards the front and through the switching array, the lens having a length substantially equal to the length of the illuminating line.