Digital Display Delta-Sigma Modulation for False Contour Reduction
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Solution Overview
Problem
Current display technologies face issues with uniformity, color balance, and energy efficiency, particularly in non-emissive LCDs and emissive OLEDs, leading to power consumption challenges and the creation of lateral field contouring due to binary-weighted PWM modulation.
Innovation Solution
The implementation of a Delta Sigma (ΔΣ) Pulse Density Modulation (PDM) system, which reduces power consumption by using fewer bits-per-component and increases bit-depth to correct uniformity and color inversion, while allowing for faster display operation and reduced bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If binary-weighted PWM modulation is used to drive display pixels, then the display can achieve standard brightness levels, but lateral field contouring (false contouring) occurs and power consumption increases
Solution Approach 1:
The patent changes the modulation parameter from binary-weighted PWM to Delta Sigma PDM, fundamentally altering how brightness is encoded. Instead of using multiple bits per component with binary weighting, the system uses 1-bit PDM with temporal density modulation, eliminating false contouring while maintaining brightness perception through human eye integration of rapid bit transitions
Solution Approach 2:
The patent employs periodic high-frequency bit transitions in Delta Sigma PDM modulation, where bits alternate rapidly (e.g., 10 MHz) to encode brightness information through temporal density rather than amplitude. This periodic action at frequencies above the human visual threshold prevents false contouring while the eye integrates the density of high bits to perceive correct brightness levels
2Measurement precision
If bit-depth (N) is increased to reduce false contouring, then image quality improves, but total power consumption increases exponentially according to Ptotal=Pstep*2N
Solution Approach 1:
The patent fundamentally changes the parameter representation from N-bit binary-weighted values to 1-bit PDM temporal sequences. Instead of increasing bit-depth to improve quality, the system uses fixed 1-bit transitions where image quality is maintained through the human eye's temporal integration of bit density, completely decoupling precision requirements from power consumption
Solution Approach 2:
The patent creates a temporal copy of brightness information through repeated high-frequency bit transitions. Rather than using more bits to represent brightness levels, the system encodes the same brightness information multiple times in rapid succession using 1-bit PDM, allowing the human eye to integrate these copies and perceive accurate brightness without increasing power consumption
3Measurement precision
If PWM circuit runs faster to resolve more steps (2N steps for N-bit), then false contouring is reduced, but system complexity and power requirements increase
Solution Approach 1:
The patent changes the fundamental parameter encoding from N-bit parallel binary-weighted values to 1-bit sequential PDM transitions. This eliminates the need for complex N-bit PWM circuits and their associated 2N steps, replacing them with simple 1-bit toggling that requires minimal circuitry while achieving equivalent or superior grey level resolution through temporal integration
Solution Approach 2:
The patent extracts only the essential brightness information and encodes it in a single bit stream, removing the complexity of multi-bit parallel processing. By taking out just the necessary 1-bit PDM signal and relying on temporal density modulation, the system eliminates unnecessary circuit complexity while maintaining full grey level capability through human visual integration
4Ease of manufacture
If non-emissive LCD technology is used for display, then manufacturing is easier, but energy efficiency is poor with only 4%-8% of backlight energy emitted
Solution Approach 1:
The patent enables emissive display operation where each pixel generates its own light through OLED elements, eliminating the need for a separate backlight unit. This self-service approach allows pixels to emit light directly, achieving near 100% energy efficiency compared to LCD's 4%-8% efficiency, while maintaining manufacturing feasibility through standard OLED fabrication processes
Data Source
AI summary
A device and method of an image processing system where a Delta Sigma Pulse Density Modulation is used for digital displays, where the digital displays are emissive or non-emissive. The device and method a digital driving solution using Delta Sigma Encoding where N bit-per-component symbols at F1 frame-rate-per-second are represented using M bits-per-component symbols at F2 frame-rate-per-second, where N≥M and F2≥F1.