LCD Power Source Circuit with Bias-Ratio Feedback
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Solution Overview
Problem
Existing power source circuits for liquid crystal displays face challenges of high power consumption and complex circuit structures due to the need for producing high voltages and ensuring voltage symmetry, which complicates the generation of stable driving voltages for liquid crystal molecules.
Innovation Solution
A power source circuit comprising a charge pump circuit, first and second control circuits, and a bias-ratio circuit, which operate in closed-loop to produce symmetrical positive and negative high voltages directly, without exceeding the liquid crystal's driving voltages, thereby reducing power consumption and simplifying the circuit structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a charge pump circuit is used to produce high voltages for liquid crystal driving, then the drive voltage can be achieved, but the circuit structure becomes complex and power consumption increases
Solution Approach 1:
The patent combines the positive high voltage generation and negative high voltage generation into a single integrated charge pump circuit. The charge pump simultaneously produces both positive and negative high voltages through its internal capacitor charging and discharging mechanisms, eliminating the need for separate voltage generation circuits and reducing overall circuit complexity.
Solution Approach 2:
The charge pump circuit is designed to perform multiple functions: it generates positive high voltage, generates negative high voltage, and provides voltage regulation through feedback control. This multi-functional design replaces what would traditionally require multiple separate circuits, thereby reducing device complexity while maintaining the required drive voltage capabilities.
2Stability of the object's composition
If an LDO or additional structure is used to regulate the charge pump output, then stable high voltage is achieved, but circuit complexity and power consumption increase
Solution Approach 1:
The patent implements a feedback control mechanism where the generated high voltages are monitored and fed back to the charge pump control logic. This feedback enables the charge pump to self-regulate its output voltage levels, maintaining stability without requiring external LDO regulators or additional voltage adjustment circuits, thus avoiding increased complexity.
3Power
If voltage higher than liquid crystal driving voltage is produced, then voltage regulation is needed, but this leads to complex circuit structure and high power consumption
Solution Approach 1:
The charge pump circuit is designed to generate voltages that are precisely sufficient for liquid crystal driving requirements rather than producing excessive high voltages. By controlling the charge pump to output voltages within the optimal range (e.g., +20V to -20V for typical LCD applications), the system avoids the need for additional voltage regulation stages, thereby reducing power consumption and circuit complexity.
4Measurement precision
If separate circuits are used for positive and negative voltage generation, then voltage control is improved, but circuit complexity increases
Solution Approach 1:
The patent integrates both positive and negative voltage generation functions into a single charge pump circuit with unified control. The charge pump uses its internal capacitor network to simultaneously produce symmetric positive and negative high voltages, providing precise voltage control for both polarities while maintaining a compact, low-complexity circuit structure.
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 achieves low power consumption and reduced circuit complexity by directly producing stable high voltages within the required range for liquid crystal displays, ensuring consistency and symmetry of voltage changes, thus enhancing display quality and reliability.
Implementation Method 1
a charge pump circuit, used in operating the charge pump to produce driving voltages
Data Source
AI summary
This invention is suitable for use in the field of integrated circuits. It provides a type of power source circuit. Said power source circuit includes: a charge pump circuit used to operate the charge pump to produce driving voltages; a first control circuit, used in the closed-loop control of said charge pump circuit to produce a positive high voltage; a bias-ratio circuit, used with the positive high voltage and the zero-potential voltage produced by the first control circuit to produce a positive sub-high voltage and a lowest positive high voltage; and a second control circuit, used in accordance with the positive sub-high voltage and the lowest positive high voltage produced by said bias-ratio circuit in the closed-loop control of said charge pump circuit to produce a negative high voltage. Using this invention, the system contains no voltage higher than the liquid crystal's driving voltages, and also does not contain any lower negative voltage than the liquid crystal's highest negative driving voltage, thereby reducing the circuit's electrical consumption.