LED Display Color Gamut Expansion via Independent Drive Vector Optimization
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Solution Overview
Problem
Current LED display systems struggle to produce highly saturated colors at night due to limited brightness control, especially when using more than three basis colors, as they rely on a common scaling factor that restricts luminous intensity variations below 100 Hz, leading to flicker sensations and reduced color gamut expansion.
Innovation Solution
A method and apparatus that compute and apply a maximum luminous intensity and associated LED drive vector using mathematical programming techniques, allowing for interpolation and constraint-based LED drive vector scaling to display highly saturated colors across a broad gamut without sacrificing luminosity, even when desired colors are outside the computed set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a common scaling factor is applied to all LED drivers to control overall brightness, then the system maintains simple brightness control, but the ability to produce highly saturated colors at lower luminance levels is lost
Solution Approach 1:
The patent changes the control parameters from a single common scaling factor to multiple independent drive coefficients (one for each basis color LED string). This allows each color channel to be independently optimized for luminous intensity while maintaining overall brightness control, enabling highly saturated colors at lower luminance levels without the limitations of uniform scaling.
2Adaptability or versatility
If more than three basis colors are used to expand the color gamut, then the gamut and color saturation are improved, but the complexity of LED driver control increases
Solution Approach 1:
The patent implements dynamic optimization by using mathematical programming techniques to compute optimal drive coefficients in real-time based on the desired color output. This dynamic approach adapts the control strategy to each specific color requirement, maximizing gamut utilization while managing control complexity through algorithmic optimization rather than fixed control logic.
Solution Approach 2:
The patent transforms the control problem by changing from fixed control ratios to dynamically optimized drive coefficients. Each basis color LED string receives independently optimized control signals based on the target color and current operating conditions, allowing the system to exploit the expanded gamut of multi-color displays while managing complexity through mathematical optimization.
3Reliability
If LED drive current is pulse modulated at frequencies above 100 Hz to avoid flicker, then flicker sensation is eliminated, but the ability to achieve high luminous intensity varies受限 due to duty cycle limitations
Solution Approach 1:
The patent employs pulse modulation at frequencies above 100 Hz to eliminate flicker while using duty cycle optimization to maximize luminous intensity. By independently controlling the drive coefficients of each basis color LED string, the system can optimize the periodic pulse patterns to achieve high perceived brightness without causing flicker sensations, resolving the trade-off between flicker avoidance and luminous intensity.
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
Enables the display of highly saturated colors with expanded gamut capabilities at lower luminance levels, maintaining hue preservation and achieving maximum luminous intensity variations within predetermined constraints, thereby improving color rendering at night without flicker.
Implementation Method 1
The most common basis colors used in such a display are provided by red-, green-, and blue-emitting LEDs
Implementation Method 2
As the human psychovisual system has a frequency response for temporal variations in light intensity that is essentially zero for frequencies greater than about 100 Hz
Data Source
AI summary
A method is applicable to a pixel of a graphical display that is formed by LEDs or LED strings, with the colors that can be displayed by the pixel (i.e., the color gamut) defined by an LED drive specification matrix A. The method displays a desired color at a chromaticity coordinates (xn, yn) and a luminous intensity Y by carrying out: (a) finding a maximum luminous intensity Ŷ and the associated LED drive vector {circumflex over (b)} for each of a collection of sample colors in the color gamut using a mathematical programming technique; and (b) calculating the LED drive vector for the desired color; and (c) displaying the color on the pixel using the calculated drive vector. In one implementation, the calculated LED drive vector is scaled using the expressionb^min(YY^,1).(b) based on we sample colors. In addition, the method may create an interpolation function ƒ(x, y) for luminous intensity Ŷ and LED drive vector {circumflex over (b)} for colors outside of the sample colors. The interpolation function is used to evaluate ƒ(xn, yn) to obtain luminous intensity Ŷ and LED drive vector {circumflex over (b)} for the desired color. The interpolation function may be created off-line, and calculating the LED drive may be carried out in real time.