Common Voltage Calibration Circuit for Display Devices
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Solution Overview
Problem
Liquid crystal display devices face issues with common voltage stability due to interference from load coupling, leading to display defects like cross-talk and afterimage, which existing calibration methods cannot fully address.
Innovation Solution
A common voltage calibration circuit comprising a difference circuit, compensation circuits (proportional, integral, and differential), and a summing circuit to accurately adjust and stabilize the common voltage by amplifying, integrating, and differentiating feedback signals, thereby reducing steady-state errors and overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple voltage feedback method is used, then the circuit complexity is reduced, but the common voltage stability and control precision deteriorate due to inability to compensate for coupling interference
Solution Approach 1:
The patent implements a feedback mechanism where the common voltage is continuously monitored and compared with a reference voltage. The difference signal is fed back through proportional, integral, and differential compensation circuits to dynamically adjust and stabilize the common voltage, resolving the contradiction between simple feedback and voltage stability.
Solution Approach 2:
The patent changes the parameters of the compensation circuits (proportional gain, integral time constant, differential gain) to optimize the common voltage stabilization performance. By adjusting these parameters, the system achieves high stability and precision while managing circuit complexity.
2Speed
If proportional compensation is applied to rapidly respond to voltage changes, then the response speed is improved, but overshoot and oscillation occur affecting stability
Solution Approach 1:
The patent applies preliminary action through the differential compensation circuit that predicts future voltage trends based on the rate of change. This allows the system to take preventive measures before significant deviations occur, achieving fast response without overshoot by anticipating and counteracting potential instability.
Solution Approach 2:
The differential component of the feedback provides derivative action that opposes rapid changes in voltage. This feedback mechanism dampens oscillations and prevents overshoot while maintaining fast response capability, resolving the contradiction between speed and stability.
3Measurement precision
If integral compensation is used to eliminate steady-state error, then the control precision is improved, but the response time increases due to accumulation process
Solution Approach 1:
The patent combines integral compensation with proportional and differential actions to achieve preliminary correction of voltage deviations. The proportional component provides immediate response while the integral component systematically eliminates steady-state error, and the differential component anticipates future errors, together achieving both precision and fast response.
Solution Approach 2:
The patent merges proportional, integral, and differential compensation circuits into a unified PID control system. This combination allows the system to simultaneously achieve fast response (from proportional and differential components) and high precision (from integral component) without the time penalty of pure integral control.
4Manufacturing precision
If multiple compensation circuits are combined to improve control accuracy, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The patent merges multiple compensation functions (proportional, integral, differential) into an integrated control circuit architecture. By combining these functions in a unified structure rather than separate independent circuits, the system achieves high control accuracy while minimizing the increase in device complexity through shared components and coordinated operation.
Data Source
AI summary
A common voltage calibration circuit and a driving method thereof, a circuit board and a display device are provided. The common voltage calibration circuit includes a difference circuit, a compensation circuit and a summing circuit; the difference circuit is configured to perform a difference processing on a common voltage provided by the common voltage input terminal and a feedback common voltage provided by the common voltage feedback terminal to output a difference value signal; the compensation circuit is configured to receive the difference value signal and compensate the common voltage based on the difference value signal; and the summing circuit is configured to superimpose at least two compensation signals output by the compensation circuit and output through the common voltage output terminal.