Integrated Color LED Micro-Display With Color Conversion and Low Power
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Solution Overview
Problem
Existing color micro-displays face issues such as high power consumption, low brightness, and inefficiencies due to the need for constant illumination of all pixels, complex OLED structures, and challenges in manufacturing small pixel pitches with external pattern generators and electrical contacts.
Innovation Solution
The development of an integrated color LED micro-display using a GaN layer with p and n doped regions, an ohmic current spreading layer, and a substrate, combined with a color conversion layer and optical features like micro-lenses to enhance light emission and minimize crosstalk, along with low-temperature bonding techniques for backplane integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If OLED technology with white light and color filters is used for color micro-display, then color gamut is achieved, but 60-70% of spectral range is lost and only 10-20% of emitted light is useful
Solution Approach 1:
The display is divided into separate red, green, and blue sub-pixels, each emitting its specific wavelength directly without requiring broad-spectrum white light and color filters. This segmentation eliminates the 60-70% spectral loss inherent in white OLED displays by converting the single broad-spectrum source into multiple narrow-spectrum sources.
Solution Approach 2:
Each pixel location is assigned a specific color function (red, green, or blue) with optimized emission characteristics for that particular wavelength. The micro-LEDs are engineered with specific compositions and structures to emit only the required color, maximizing local light efficiency rather than wasting energy on unnecessary spectral ranges.
2Illumination intensity
If external pattern generators are used to form micro-display images, then image formation is achieved, but power consumption increases and contrast ratio is compromised
Solution Approach 1:
The micro-LEDs are driven in a time-multiplexed manner where only the required pixels are activated at any given moment to display the image. This periodic activation of specific pixels eliminates the need for continuous illumination of all pixels, dramatically reducing power consumption while maintaining image quality and contrast ratio.
Solution Approach 2:
Instead of using a continuously illuminated background with external pattern generators to create images, the invention inverts the approach by using self-emissive micro-LEDs that are activated only when needed. This inversion from passive illumination to active selective emission reduces power consumption and improves contrast.
3Ease of manufacture
If pick and place techniques are used for surface mount bonding of individual LEDs, then large LEDs can be mounted, but pixel pitch is limited and two electrical contacts per pixel are required
Solution Approach 1:
The n-type and p-type contact layers are merged into a single integrated structure on the same substrate, eliminating the need for separate mounting operations for each contact. This integration allows the entire micro-LED with both contacts to be handled as one unit, enabling finer pixel pitches that would be impossible with separate contact mounting.
Solution Approach 2:
The contact structure is extended into the vertical dimension with the n-type layer positioned beneath the active region and the p-type layer on top, allowing electrical contacts to be made from opposite sides of the device. This three-dimensional contact arrangement enables more compact pixel designs and finer pitch.
4Illumination intensity
If blue OLED wavelength region is used, then blue color emission is achieved, but efficiencies are poor and lifetimes are limited
Solution Approach 1:
The material composition and structural parameters of the blue light-emitting layer are optimized to improve efficiency and stability. By adjusting the quantum well composition, barrier layer thickness, and doping concentrations, the patent achieves high-efficiency blue emission with extended operational lifetime, overcoming the inherent limitations of conventional blue OLEDs.
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 results in a low power consumption, high brightness display with improved light extraction and reduced optical crosstalk, enabling larger display dimensions and lower production costs.
Implementation Method 1
a GaN layer comprising p and n doped GaN regions and layers optimized for efficient light generation
Implementation Method 2
optical features like micro-lenses to enhance light emission
Implementation Method 3
combined with a color conversion layer
Data Source
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AI summary
There is herein described a low power consumption high brightness display. More particularly, there is described an integrated LED micro-display and a method of manufacturing the integrated LED micro-display.