LCD Control Circuit Shift Error Correction for Brightness Stability
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Solution Overview
Problem
Conventional liquid crystal display controlling devices experience unstable pixel brightness due to temperature and voltage-induced dynamic drift in the A/D interface, leading to conversion errors and shifts in white balance, particularly during the display of primary colors like red, green, and blue.
Innovation Solution
A video processing circuit incorporating a shift error correction circuit, which includes a sampler, a clamping pulse generator, and an infinite impulse response (IIR) filter, corrects the conversion errors by generating a correction signal to stabilize pixel brightness and compensate for manufacturing errors, thereby eliminating pixel brightness drift and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an A/D interface is used to convert analog video signals to digital signals, then video conversion is achieved, but dynamic drift occurs due to temperature and voltage changes causing conversion errors and unstable pixel brightness
Solution Approach 1:
The patent implements a feedback mechanism where the A/D interface continuously monitors its own conversion results and compares them against reference values. When drift is detected due to temperature or voltage changes, the system generates correction signals that are fed back to adjust the conversion operation point, thereby maintaining accurate conversion despite environmental variations.
Solution Approach 2:
The patent dynamically adjusts the conversion operation point parameters of the A/D interface based on detected drift conditions. By changing the reference voltage levels and conversion thresholds in real-time, the system compensates for temperature and voltage-induced drift, maintaining both conversion accuracy and pixel brightness stability.
2Manufacturing precision
If conventional A/D conversion is used without correction, then device complexity is low, but manufacturing errors cause white balance shifts and affect display quality
Solution Approach 1:
The patent incorporates correction circuits and sampling mechanisms that are activated during the manufacturing process or initial setup phase. These circuits pre-calculate and store correction values for expected manufacturing variations, which are then applied during normal operation to compensate for manufacturing errors without requiring complex real-time adjustments.
Solution Approach 2:
The patent introduces intermediary correction circuits that act as mediators between the A/D interface and the display output. These intermediary circuits process the converted digital signals and apply corrections for manufacturing errors, isolating the main A/D conversion circuit from the display quality requirements and allowing independent optimization of each component.
Data Source
AI summary
A controlling device of a liquid crystal display is provided. The controlling device includes an A/D interface, a sampler, and a shift error correction circuit. An input end of the A/D interface receives an analog video signal for being converted, so as to output a digital video color level. The sampler is coupled between a reference potential and the input end of the A/D interface, and a controlling end of the sampler receives a correction signal. The shift error correction circuit receives the digital video color level, the correction signal, and a target value corresponding to the reference potential. When the correction signal is enabled, the sampler is ON, and the shift error correction circuit performs a correction operation on the received digital video color level and the target value to get a correction value for the A/D interface that corrects the conversion error of the A/D interface.