Hybrid Analog Digital LED Backlight Controller Architecture

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Solution Overview

Problem

Existing controllers for LED backlighting in large displays face issues with real-time control due to noise and delays inherent in analog circuits, and slow startup periods in digital systems, leading to suboptimal performance and difficulty in programming and debugging during operation.

Innovation Solution

A hybrid controller combining analog and digital circuit components, where error amplifiers compare analog feedback signals with reference signals, and the results are processed by a digital signal processor to calculate drive voltages for LED strings, with analog drivers providing continuous voltage during DSP initialization or shutdown, and a multiplexor enabling sequential processing of LED strings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If analog circuits are used for real-time control of LED strings, then real-time control capability is improved, but noise and delays affect control precision

Engineering Contradiction:

Improvereal-time control speedVSAvoidcontrol precision

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The control system is segmented into separate functional modules: error amplifiers for analog signal processing, ADC for digital conversion, DSP for intelligent processing, and DAC for analog output. This segmentation allows each module to optimize for its specific function, achieving both real-time response and high precision without the drawbacks of purely analog or digital systems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces ADC and DAC as intermediary components between the analog error amplifiers and the digital DSP. The ADC converts analog error signals to digital form for precise DSP processing, while the DAC converts digital control signals back to analog form for LED driver actuation. These intermediaries enable the system to achieve both real-time control and high precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If digital systems are used for controller, then programming and debugging capability is improved, but startup period becomes slow

Engineering Contradiction:

Improveprogramming and debugging easeVSAvoidstartup time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The error amplifiers and analog driver circuits are designed to be pre-configured and ready for operation before the DSP initialization completes. The analog portion can immediately begin processing error signals and providing drive voltages, while the digital DSP finishes its startup sequence. This preliminary action of the analog components eliminates the startup delay that would otherwise be imposed by the digital system initialization.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent merges analog and digital control approaches into a single hybrid system. The analog error amplifiers and digital DSP operate simultaneously in parallel, with the analog portion handling immediate real-time control and the digital portion providing intelligent processing and programming capabilities. This combination allows the system to enjoy both the fast response of analog circuits and the programmability of digital systems without sacrificing startup speed.

Inventive Principle:

Principle #5Merging (Combining)

3Extent of automation

If purely digital control is used, then intelligent decision-making capability is improved, but real-time control and responsiveness are reduced

Engineering Contradiction:

Improveintelligent decision-making capabilityVSAvoidresponsiveness

Core Design Contradiction:

Extent of automationVSSpeed

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The error amplifiers continuously process error signals in real-time and the analog drivers continuously provide drive voltages to LED strings, ensuring uninterrupted control. The DSP operates in parallel, continuously receiving digital representations of error signals and providing intelligent control decisions. This continuous operation of both analog and digital components ensures neither responsiveness nor intelligent capability is compromised.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS8049708B2Hybrid analog and digital architecture for controlling backlight light emitting diodes of an electronic display

Publication Date: 2011.11.01 ATMEL CORP

AI summary

The present invention provides a controller for controlling strings of LEDs in a liquid crystal display. The hybrid controller uses both analog and digital circuit components. Error amplifiers are used to compare analog feedback signals received from the LED strings with reference signals. The results of those comparisons are converted to digital data and processed by a digital signal processor (DSP). The DSP calculates the drive voltages for the LED strings based on the deviation between the actual current flows (represented by feedback signals) and the desired current flows (represented by reference signals) through the LED strings. Analog drivers provide the drive voltages to the LED strings.