Display Substrate Pixel Circuit for Stable OLED Gate Voltage
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Solution Overview
Problem
In OLED display substrates, the gate voltage of driving transistors can fluctuate due to leakage currents, leading to brightness changes and flicker phenomena, which degrade display quality.
Innovation Solution
A pixel circuit design incorporating a voltage stabilizing capacitor coupled to the gate of a driving transistor, along with a storage capacitor to maintain a stable driving voltage, and a series of transistors for reset and writing operations to stabilize the gate voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a driving transistor is used to drive the OLED in the luminescence stage, then the OLED can emit light with corresponding brightness, but the gate voltage of the driving transistor changes due to leakage current, resulting in brightness change and flicker phenomenon
Solution Approach 1:
The patent applies preliminary action by setting the initialization voltage of the first transistor higher than the initialization voltage of the second transistor before the luminescence stage begins. This pre-established voltage difference compensates for the voltage drop caused by leakage current during the holding period, ensuring that the gate voltage of the driving transistor remains stable throughout the luminescence stage, thereby preventing brightness changes and flicker phenomena.
2Reliability
If the gate voltage is maintained stable to prevent brightness change, then display quality improves, but additional circuit components (voltage stabilizing capacitor, extra transistors) are required
Solution Approach 1:
The patent applies universality by designing the first and second transistors to serve multiple functions: they act as switching transistors during the reset and writing stages, and simultaneously function as voltage compensation elements during the luminescence stage due to their different initialization voltages. The voltage stabilizing capacitor also serves dual purposes by maintaining the gate voltage of the driving transistor and compensating for leakage current effects, thereby reducing the need for additional dedicated compensation circuits.
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 design stabilizes the driving voltage, reducing brightness fluctuations and preventing flicker, thereby enhancing display quality by maintaining consistent light emission.
Implementation Method 1
a voltage stabilizing capacitor having a first electrode coupled to the second electrode of the second transistor, and a second electrode coupled to a constant voltage signal source
Implementation Method 2
a storage module configured to maintain and provide the driving voltage to the driving module in the luminescence stage; the storage module includes a storage capacitor having a first electrode coupled to the gate of the driving transistor and configured to maintain the driving voltage
Implementation Method 3
a light emitting module configured to emit light; the light emitting module includes a light emitting device; a driving transistor configured to drive the light emitting device to emit light based on a voltage at a gate of the driving transistor
Data Source
AI summary
A display substrate and a display apparatus are provided, and the display substrate includes a pixel circuit with a light emitting module configured to emit light; a driving module configured to drive the light emitting module to emit light based on a driving voltage in a luminescence stage; a storage module configured to maintain and provide the driving voltage to the driving module in the luminescence stage; a first transistor, having a first electrode coupled to a position from which the driving module acquires the driving voltage; a second transistor, having a first electrode coupled to the first electrode of the first transistor, and a second electrode being not directly coupled to a signal source; and a voltage stabilizing capacitor, having a first electrode coupled to the second electrode of the second transistor, and a second electrode coupled to a constant voltage signal source.