Source Driver IC Equalizer Control for Signal Glitch Prevention
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Solution Overview
Problem
The existing Embedded Panel Interface (EPI) protocol for liquid crystal display devices experiences signal distortion and waveform glitches due to external noise and impedance mismatching when connected in a multidrop manner, leading to malfunction of source driver ICs and abnormal noise on the screen.
Innovation Solution
Incorporating an equalizer control circuit in the source driver ICs that initializes the equalizer when the clock recovery circuit is in an unlock state and the equalization setting value is changed, preventing signal boosting and maintaining a stable clock recovery loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the equalizer boosts the data signal to compensate for signal loss, then the signal strength is improved, but signal distortion and waveform glitches occur due to external noise and impedance mismatching
Solution Approach 1:
The patent changes the equalization setting value parameter to control the equalizer's boosting level. By dynamically adjusting this parameter based on lock status, the system optimizes signal strength while preventing over-boosting that causes distortion and waveform glitches.
Solution Approach 2:
The patent implements a feedback mechanism where the clock recovery circuit's lock status is monitored and fed back to the equalizer control circuit. When the lock status is unstable or lost, the feedback triggers initialization of the equalizer, preventing signal distortion and waveform glitches from occurring.
2Reliability
If the equalizer continuously boosts the signal with high EQ setting value, then signal reception is improved, but the clock recovery circuit cannot lock due to waveform distortion
Solution Approach 1:
The patent makes the equalizer's operation dynamic by changing its behavior based on clock recovery lock status. When locked, the equalizer operates with higher boosting; when unlocked or transitioning, it initializes to a neutral state, allowing the system to adapt to changing signal conditions and maintain both reception quality and clock recovery accuracy.
Solution Approach 2:
The patent applies preliminary anti-action by initializing the equalizer before clock recovery attempts when the lock status is unstable. This prevents waveform distortion from occurring in the first place, ensuring that the clock recovery circuit can successfully lock without interference from distorted waveforms.
3Stability of the object's composition
If the equalizer is initialized frequently to prevent distortion, then waveform stability is improved, but the signal strength may become insufficient for reliable reception
Solution Approach 1:
The patent uses feedback from the clock recovery circuit's lock status to control equalizer initialization. The equalizer is initialized only when the lock status is unstable or lost, not continuously. This selective feedback-based approach maintains waveform stability while preserving signal strength for reliable reception during normal operation.
Data Source
AI summary
A display device includes a source driver integrated circuit (IC) including an equalizer for boosting a data signal received through a pair of signal lines depending on an equalization (EQ) setting value and a clock recovery circuit recovering a clock of the data signal, and a timing controller, which is connected to the source driver IC through the signal line pair and transmits the data signal to the source driver IC. The source driver IC samples the data signal in conformity with a timing of an internal clock output when the clock recovery circuit is in a lock state. The source driver IC further includes an equalizer control circuit for initializing the equalizer when the clock recovery circuit is in an unlock state and the EQ setting value is changed.