Adjustable Phase Delay Circuit for TFT-LCD Ghost Shadow Reduction
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Solution Overview
Problem
Existing systems for thin film transistor liquid crystal displays (TFT-LCDs) face issues with ghost shadows and crosstalk due to long liquid crystal reaction times, requiring complex and costly circuit layouts and microprocessors to achieve phase delay, which increases system complexity and cost.
Innovation Solution
A circuit with a delay setting unit and phase delay signal generator, utilizing external resistors to set delay times and generate phase delay signals for multiple lighting modules, along with a sample and hold unit to stabilize feedback voltage, eliminating the need for multiple dimming signals and microprocessors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple pulse width modulation signals are provided to achieve phase delay, then phase delay function is improved, but circuit layout complexity increases
Solution Approach 1:
The patent divides the phase delay function into multiple independent phase delay units, where each unit corresponds to a lighting module. Each phase delay unit contains an edge trigger subunit and a signal generation subunit that independently generates phase delay signals. This segmentation allows the system to achieve phase delay for multiple lighting modules without requiring complex centralized control circuits, thereby reducing overall circuit layout complexity while maintaining the phase delay function.
Solution Approach 2:
Each phase delay unit is designed to autonomously generate phase delay signals based on local edge trigger signals and delay time settings. The edge trigger subunit automatically detects positive and negative edges of input signals and generates corresponding trigger signals, while the signal generation subunit independently creates phase delay outputs. This self-service capability eliminates the need for complex external control circuits, reducing circuit layout complexity while maintaining phase delay functionality.
2Measurement precision
If microprocessor is used to control phase delay in digital method, then phase delay control precision is improved, but system cost increases
Solution Approach 1:
The patent replaces the microprocessor-based digital control system with an analog circuit-based phase delay generation system. Each phase delay unit uses edge trigger subunits and signal generation subunits that operate through analog electronic circuits rather than digital processing. This substitution eliminates the need for expensive microprocessors while achieving precise phase delay control through circuit-level timing mechanisms, thereby reducing system cost while maintaining control precision.
Solution Approach 2:
The patent employs inexpensive discrete electronic components (resistors, capacitors, transistors) to implement phase delay control instead of using expensive microprocessors. The delay setting units use simple external resistors that can be easily adjusted, and the phase delay units use standard electronic components that are cost-effective and readily available. This approach significantly reduces system cost while achieving the required phase delay control precision through clever circuit design rather than expensive processing hardware.
3Adaptability or versatility
If delay time is adjusted according to external resistor, then adaptability is improved, but circuit complexity increases
Solution Approach 1:
The patent implements delay time adjustment by changing the resistance value of external resistors connected to delay setting units. Each phase delay unit has a delay setting unit that receives an external resistor, and the delay time is determined by the resistance value. This parameter-based adjustment mechanism allows flexible adaptation to different lighting scenarios without requiring complex control logic or additional circuitry. The circuit complexity remains low because the adjustment is achieved through simple resistor parameter changes rather than complex reconfiguration mechanisms.
Data Source
AI summary
A circuit with adjustable phase delay and a feedback voltage includes a delay setting unit and a phase delay signal generator. The delay setting unit generates a delay time according to an external resistor. The phase delay signal generator includes a plurality of phase delay units. Each phase delay unit includes an edge trigger subunit and a signal generation subunit. The edge trigger subunit receives an input signal, and generates a positive edge trigger signal and a negative edge trigger signal according to a positive edge and a negative edge of the input signal, respectively. The signal generation subunit generates and outputs a phase delay signal according to the positive edge trigger signal, the negative edge trigger signal, and the delay time. The phase delay signal lags the input signal for the delay time.