VCOM Calibrator Circuit Using Programmable Resistive Arrays
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Solution Overview
Problem
Existing VCOM calibrators for LCD panels face challenges with mechanical potentiometers, including poor resolution, reliability, and labor-intensive mass production, as well as limitations with digital calibrators that require external resistors and trade-offs between adjustment range and resolution.
Innovation Solution
A VCOM calibrator circuit using integrated programmable resistive arrays with two DACs and a set resistor, allowing for precise adjustment of the VCOM voltage within the desired range without external resistors, enabling both coarse and fine adjustments for optimal flicker reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical potentiometers are used for VCOM adjustment, then the adjustment process is simple, but the resolution and reliability are poor and mass production is labor-intensive
Solution Approach 1:
The patent replaces mechanical potentiometers with a digital control system consisting of a microcontroller and electronic components. The microcontroller digitally adjusts the VCOM voltage through programmed control, eliminating mechanical moving parts while achieving higher reliability and enabling automated mass production.
Solution Approach 2:
The system incorporates automatic calibration functionality where the microcontroller autonomously adjusts VCOM voltage based on feedback from voltage detection circuits, eliminating the need for manual mechanical adjustment and enabling self-calibration during manufacturing or operation.
2Ease of operation
If digital VCOM calibrators with external resistors are used, then the adjustment process is simplified, but there is a trade-off between adjustment range and resolution
Solution Approach 1:
The patent implements a dynamic adjustment mechanism where the microcontroller can adaptively change the adjustment range and resolution based on the detected VCOM voltage level. The system switches between coarse adjustment mode (for broader range) and fine adjustment mode (for higher precision), optimizing both range and resolution throughout the adjustment process.
Solution Approach 2:
The adjustment process is divided into multiple stages or segments: a first adjustment stage with lower resolution for covering the full VCOM range, and a second adjustment stage with higher resolution for precise calibration. This segmented approach allows the system to achieve both wide adjustment range and high precision without being constrained by fixed resistor values.
3Ease of manufacture
If external resistors are used in VCOM calibrators, then the circuit implementation is straightforward, but the device complexity increases due to additional external components
Solution Approach 1:
The patent integrates the resistor functions directly into the microcontroller's internal circuitry or combines them with on-chip components. The microcontroller's digital-to-analog conversion capabilities and internal reference voltage circuits replace the need for separate external resistor networks, reducing component count while maintaining circuit functionality.
Solution Approach 2:
The microcontroller serves multiple functions: it performs digital-to-analog conversion for VCOM adjustment, detects the actual VCOM voltage level through built-in ADC circuits, controls the adjustment process, and stores calibration data. This multi-functional integration eliminates the need for dedicated external components that would otherwise be required for each function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides a reliable, efficient, and automated method for adjusting VCOM voltage, improving resolution and reducing manufacturing complexity by eliminating the need for external components, ensuring precise VCOM voltage settings for optimal LCD display performance.
Implementation Method 1
a first DAC, a second DAC, a first resistor coupled between a power supply voltage and a calibrator output having an adjustable value controlled by the first DAC
Implementation Method 2
a second resistor coupled between the calibrator output and ground having an adjustable value controlled by the first DAC, and a set resistor coupled between an output of the second DAC and ground
Implementation Method 3
The calibrator includes a buffer having a first input coupled to the second DAC, a second input coupled to the set resistor, and a current output coupled to the calibrator output
Data Source
AI summary
A calibrator circuit and method for VCOM voltage adjustment for an LCD includes using integrated programmable resistive arrays. The method uses two DACs and three integrated circuit arrays to provide all of the advantages of VCOM calibrator circuits using external resistive voltage-dividers. The integrated circuit resistor arrays reduce the number of external components and PCB space. The method used is suitable for higher resolution adjustment of the VCOM voltage and no calculation is required in the whole adjustment procedure, which saves labor cost, time and enables automation of the calibrator fabrication.