Pixel Circuit Constant Current Drive for OLED Gray Scale Efficiency
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Solution Overview
Problem
Inorganic light-emitting diode display panels struggle to fully utilize high luminous efficiency in low gray scale cases due to the limitations of existing pixel circuits, which result in lower luminance and affected display effects.
Innovation Solution
A pixel circuit comprising a data voltage write module, storage module, discharge module, comparison module, and drive module, where the comparison module generates a constant drive current by comparing stored data voltage with a reference voltage, allowing for different gray scales through varying light emission durations rather than current magnitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the display gray scale is controlled by varying drive current magnitude, then different gray scales can be achieved, but the luminous efficiency of inorganic light-emitting diode cannot be fully utilized in low gray scale cases
Solution Approach 1:
The patent changes the control parameter from drive current magnitude to light emission duration. The drive module generates a constant drive current regardless of gray scale level, and the light-emitting module emits light for different durations corresponding to different gray scales. This parameter change allows the inorganic light-emitting diode to operate at high current density (high luminous efficiency) while still achieving different gray scales through temporal modulation rather than magnitude modulation.
2Loss of energy
If a constant drive current is used to drive the inorganic light-emitting diode, then high luminous efficiency can be maintained, but different gray scales cannot be achieved through current magnitude variation
Solution Approach 1:
The patent employs periodic action by modulating the light emission duration of the inorganic light-emitting diode. The drive module generates a constant drive current, and the light-emitting module is activated for specific time periods corresponding to different gray scales. This temporal modulation (periodic on/off action) enables gray scale control while maintaining constant high current density during emission, thus preserving high luminous efficiency across all gray scale levels.
3Device complexity
If the pixel circuit uses traditional drive transistor control, then the structure remains simple, but the high luminous efficiency of inorganic light-emitting diode cannot be utilized in low gray scale cases
Solution Approach 1:
The patent segments the pixel circuit into distinct functional modules: a drive module for generating constant drive current, a storage module for storing data voltage, a discharge module for controlling discharge timing, and a light-emitting module for optical output. This segmentation allows independent optimization of each module, enabling the drive module to maintain constant high current while the discharge module controls emission duration to achieve different gray scales, thus resolving the contradiction between structural simplicity and luminous efficiency.
4Ease of operation
If data voltage directly controls drive transistor gate, then the control method is simple, but low gray scale performance suffers due to insufficient current density
Solution Approach 1:
The patent introduces an intermediary mechanism between data voltage input and light emission output. The storage module stores the data voltage, and the discharge module acts as an intermediary that controls the timing and duration of voltage discharge to the drive module. This intermediary mechanism decouples the simple voltage input from the current control, allowing the drive module to generate constant high current density while the discharge timing (controlled by the intermediary) determines the emission duration and thus the gray scale level, improving luminance in low gray scale cases.
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 enables the inorganic light-emitting diode to maintain high luminous efficiency across all gray scales, including low gray scales, by controlling light emission duration, thereby improving display performance.
Implementation Method 1
an inorganic light-emitting diode display panel
Implementation Method 2
high luminous efficiency
Data Source
AI summary
Disclosed are a pixel circuit, a drive method thereof and a display panel. The pixel circuit includes: a discharge module, a storage module, a comparison module, and a drive module. The drive module is configured to drive, according to a voltage outputted through the output end of the comparison module, a light-emitting module to emit light. In a light-emitting phase, the discharge module discharges the storage module; and the comparison module compares an input voltage received from the first input end with a reference voltage received from the second input end and outputs, to the control end of the drive module, a constant voltage for turning on the drive module or a voltage for turning off the drive module, so that the drive module generates a constant drive current when being turned on.