Display Device Pixel Circuit Floating State Voltage Stabilization
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Solution Overview
Problem
High-definition liquid crystal displays in mobile terminals consume significant power, making it difficult to drive them for long periods with a battery, and existing methods to reduce power consumption, such as driving at low voltage amplitude, are hindered by leak currents that degrade image quality.
Innovation Solution
The implementation of a display device with pixel circuits comprising a liquid crystal element, a capacitor, and switches that maintain the liquid crystal layer in a floating state, even when leak current occurs, to stabilize the voltage applied and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the liquid crystal display is driven at low voltage amplitude to reduce power consumption, then power consumption is reduced, but the leak current of the TFT cannot be neglected and voltage fluctuation degrades image quality
Solution Approach 1:
A capacitor is introduced as an intermediary element between the pixel electrode and common electrode. This capacitor maintains a stable voltage across the liquid crystal layer by compensating for TFT leak current, thereby preserving image quality while enabling low-voltage operation. The capacitor acts as a buffer that decouples the voltage stability requirement from the TFT's inherent leakage characteristics.
Solution Approach 2:
The invention changes the operating voltage parameter from conventional high voltage to low voltage amplitude. By operating at reduced voltage levels (e.g., 0V to 3.3V instead of traditional higher voltages), power consumption is significantly reduced. The capacitor ensures that despite the lower operating voltage and associated leak currents, the liquid crystal layer maintains stable voltage for proper display performance.
2Measurement precision
If the number of pixels is increased to achieve high definition, then display definition is improved, but power consumption increases significantly
Solution Approach 1:
The invention changes the voltage amplitude parameter to low voltage levels, which directly reduces power consumption (P=V²/R). This parameter change enables high-definition displays with numerous pixels to operate at lower power levels, making them suitable for battery-powered mobile terminals while maintaining high display definition.
Solution Approach 2:
The capacitor serves as a mediator that enables low-voltage operation to work effectively. By stabilizing the voltage across the liquid crystal layer despite TFT leakage, the capacitor allows the display to maintain high definition performance at reduced voltage levels, thus resolving the power consumption issue associated with high pixel counts.
3Duration of action of stationary object
If the voltage between pixel electrode and common electrode is retained by turning off TFT, then display state is maintained, but leak current causes voltage fluctuation and degrades image quality
Solution Approach 1:
The capacitor is positioned as an intermediary between the pixel electrode and common electrode to maintain stable voltage during the display period. When the TFT is turned off to retain voltage, the capacitor compensates for voltage drops caused by leak current, ensuring that the liquid crystal layer maintains proper voltage for sustained image quality without degradation over time.
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 effectively suppresses voltage variations across the liquid crystal layer, maintaining image quality and reducing power consumption, allowing for longer battery life and improved display definition.
Implementation Method 1
a capacitor which applies voltage to at least one of electrodes of the liquid crystal element
Data Source
AI summary
According to one embodiment, a display device includes pixel circuits arranged in a matrix in a display area, and the pixel circuits each includes a display element, a capacitor which applies voltage to at least one of electrodes of the display element, a first switch which supplies voltage to the capacitor when in an on state, a second switch which is set in an off state with the first switch when the first switch is in the off state, and sets the capacitor in a floating state.