Cascade LED Packages With PWM Shifting for Low-Intensity Output

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Solution Overview

Problem

Existing LED display technologies face challenges in achieving high resolution and dynamic range due to limitations in pixel pitch, driver complexity, and turn-on delay of LED chips, leading to light drop-off at low intensity levels.

Innovation Solution

Discrete LED packages are designed for cascade communication, capable of transforming and shifting PWM signals to compensate for turn-on delay, using active electrical elements with PWM processors to ensure pulse widths exceed the turn-on time of LED chips, thereby maintaining light output across the dynamic range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If discrete LED packages are arranged for cascade communication with transformation and shifting of PWM signals, then light drop-off at low intensity levels is reduced and dynamic range is increased, but device complexity increases due to integrated PWM processors in each package

Engineering Contradiction:

Improvelight output at low intensity levelsVSAvoidcomplexity of LED package with PWM processor

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The system divides the PWM signal processing function into discrete segments, with each LED package containing its own PWM processor that independently transforms and shifts received PWM signals. This segmentation allows each package to compensate for its own turn-on delay without requiring complex centralized control, thereby improving light output at low intensity levels while distributing complexity across multiple independent units.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The PWM processor in each LED package performs preliminary transformation and shifting of the PWM signal before the LED chips are activated. By pre-adjusting the pulse width to account for turn-on delay, the system ensures that the actual light output achieves the desired intensity level, effectively compensating for the delay before the LED chips begin emitting light.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If pixel pitch is decreased for higher resolution displays, then display resolution is improved, but driver complexity and cost increase due to densely populated electrical devices

Engineering Contradiction:

Improvedisplay resolutionVSAvoiddensity of electrical devices in driver

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts the PWM signal processing function from the centralized driver circuitry and relocates it into individual LED packages. Each package contains its own PWM processor that independently handles signal transformation and shifting, eliminating the need for densely populated driver circuits and reducing overall system complexity while maintaining high display resolution.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Each LED package is designed to be self-sufficient with an integrated PWM processor that autonomously transforms and shifts received PWM signals without requiring complex external driver circuitry. This self-service capability allows each package to independently compensate for its own turn-on delay and control its light output, significantly reducing the complexity of the overall driver system.

Inventive Principle:

Principle #25Self-service

3Stability of the object's composition

If PWM pulse width is increased to exceed LED turn-on time, then light output stability is improved, but time resolution is reduced due to longer pulse durations

Engineering Contradiction:

Improvelight output stabilityVSAvoidtime resolution in PWM control

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The PWM processor applies a compensating shift to the pulse width that counteracts the LED turn-on delay. By adding this counterbalancing time offset, the system ensures that the effective pulse width delivered to the LED chips is sufficient to achieve stable light output, while the overall PWM timing resolution is preserved through precise digital control of the shifted values.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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 enhances LED display performance by reducing light drop-off at low intensity levels and increasing dynamic range, allowing for improved resolution and reduced complexity in LED panel designs.

Implementation Method 1

Light-emitting diodes (LEDs) are solid-state devices that convert electrical energy to light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS12412515B2Light-emitting diode packages with transformation and shifting of pulse width modulation signals and related methods

Publication Date: 2025.09.09 CREELED INC

AI summary

Light-emitting diode (LED) packages and, more particularly, LED packages with transformation and shifting of pulse width modulation (PWM) signals and related methods are disclosed. Discrete LED packages are arranged for cascade communication. Each LED package includes one or more LED chips, and each LED package is separately capable of receiving communication from a data stream, controlling operation of the one or more LED chips, and performing transformation and shifting of received PWM signals. Transformation may include compression and/or decompression of received PWM signals by each LED package to provide increased accessible dynamic range. After transformation, LED packages are capable of shifting transformed values to compensate for turn-on delay of LED chips, thereby reducing light drop-off problems at low intensity levels.