Voltage Compensation Circuit for LCD Grayscale Uniformity
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Solution Overview
Problem
The variation in substrate temperature affects the electron mobility of TFTs in Gate on Array technology, leading to non-uniform grayscale and poor display performance in LCDs due to inconsistent driving voltages.
Innovation Solution
A voltage compensation circuit comprising a power management chip, feedback circuit, and control circuit, which adjusts the gate driving voltage using resistors, capacitors, and transistors to maintain optimal voltage levels, ensuring uniform display performance across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If GOA technology is adopted to manufacture gate scanning driving circuit on substrate, then border of panel and cost of product are decreased, but temperature variation of TFTs causes electron mobility rate drifting leading to non-uniform grayscale
Solution Approach 1:
The patent implements a feedback mechanism by introducing a feedback circuit that includes a feedback capacitor connected between the gate electrode and source electrode. This capacitor captures the voltage change caused by electron mobility rate drift and feeds it back to compensate for the grayscale non-uniformity, thereby resolving the contradiction between manufacturing simplicity and display precision
Solution Approach 2:
The patent changes the electrical parameters of the TFTs by introducing compensation capacitors that alter the voltage characteristics. By adjusting the capacitance values and connecting configurations, the system compensates for temperature-induced electron mobility variations without changing the physical structure or manufacturing process
2Use of energy by moving object
If environment temperature is low when LCD is turned on, then power consumption is reduced, but driving voltage of gate scanning driving circuit becomes too low resulting in non-uniform grayscale
Solution Approach 1:
The patent applies preliminary anti-action by pre-charging the feedback capacitor during the initialization phase before normal operation. This preliminary action ensures that when low temperature causes insufficient driving voltage, the stored charge in the capacitor provides the necessary voltage boost to maintain uniform grayscale without increasing overall power consumption
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
The circuit effectively stabilizes the gate driving voltage, enhancing display performance by adjusting voltages in response to temperature changes, thereby maintaining uniform grayscale and improving overall LCD performance.
Implementation Method 1
a voltage comparator, a fifth resistor (R5), a sixth resistor (R6) and a first capacitor (C1), a gate driving voltage (VGH) connects an input end of the control circuit, the input end of the control circuit connects to a first end of the fifth resistor (R5), and a second end of the fifth resistor (R5) connects to a forward input end of the voltage comparator
Implementation Method 2
an output end of the voltage comparator connects to a gate of the first FET (Q1), a source of the first FET (Q1) connects to the first output end of the control circuit, a drain of the first FET (Q1) connects to a second output end of the control circuit
Implementation Method 3
the feedback circuit includes a first resistor (R1), a second resistor (R2), a third resistor (R3), and a fourth resistor (R4), wherein: a first end of the first resistor (R1) connects to the output end (Output) of the feedback circuit, a second end of the first resistor (R1) connects to a first end of the second resistor (R2), a second end of the second resistor (R2) connects to a first end of the third resistor (R3), a second end of the third resistor (R3) connects to a first end of the fourth resistor (R4), a second end of the fourth resistor (R4) is grounded
Implementation Method 4
a second end of the sixth resistor (R6) and a second end of the first capacitor (C1) are grounded
Data Source
AI summary
A voltage compensation circuit and A method thereof are provided. The voltage compensation circuit includes a power management chip, a feedback circuit, and a control circuit. A gate driving voltage (VGH) connects an input end of the control circuit, the input end of the control circuit connects to a first end of the fifth resistor (R5), and a second end of the fifth resistor (R5) connects to a forward input end of the voltage comparator, and first ends of the sixth resistor (R6) and the first capacitor (C1). A second end of the sixth resistor (R6) and a second end of the first capacitor (C1) are grounded, a backward input end of the voltage comparator connects to the reference voltage (VREF), an output end of the voltage comparator connects to a gate of the first FET (Q1). With such configuration, the display performance may be enhanced.