Pixel Circuit Timing Control for Accurate OLED Gradation
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Solution Overview
Problem
Existing display devices face challenges in achieving high-resolution displays with accurate gradation implementation without shifting wavelengths due to current density variations.
Innovation Solution
A pixel design incorporating a first circuit to control the supply period of a driving current based on data signals and a second circuit to supply current corresponding to voltage differences, utilizing a complex network of transistors and capacitors to manage power supply voltages and initialization signals for precise gradation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple current supply method is used, then device complexity is reduced, but gradation accuracy deteriorates due to wavelength shifts from current density variations
Solution Approach 1:
The pixel circuit is divided into two functional segments: a first circuit responsible for controlling the supply period of driving current based on data signals, and a second circuit responsible for supplying current corresponding to voltage differences. This segmentation allows each circuit to specialize in one aspect of current control, achieving precise gradation implementation without requiring a single complex circuit to handle all functions simultaneously.
Solution Approach 2:
The first circuit performs preliminary action by controlling the supply period of the driving current in advance based on the data signal before the actual light emission occurs. This preliminary timing control establishes the foundation for accurate gradation by determining when current should be supplied to the light-emitting element, preventing wavelength shifts caused by improper timing.
2Illumination intensity
If current density is increased to improve light emission, then illumination intensity is improved, but wavelength shifts occur causing gradation inaccuracies
Solution Approach 1:
The patent implements dynamic control of the driving current supply period through the first circuit, which adjusts the timing of current supply based on the data signal. This dynamic timing adjustment allows the system to control illumination intensity through temporal modulation rather than solely through current magnitude, thereby maintaining accurate gradation while achieving the desired light emission intensity.
Solution Approach 2:
The first circuit controls the supply period of the driving current in a periodic manner based on the data signal, creating a time-dependent current supply pattern. This periodic control mechanism enables precise gradation implementation by regulating the duration and timing of current pulses to the light-emitting element, preventing wavelength shifts that would otherwise occur with continuous or improperly timed current supply.
3Device complexity
If a single circuit controls both timing and current supply, then device complexity is reduced, but light-emitting time control precision deteriorates
Solution Approach 1:
The pixel circuit is divided into two functional segments: a first circuit responsible for controlling the supply period of driving current based on data signals, and a second circuit responsible for supplying current corresponding to voltage differences. This segmentation allows each circuit to specialize in one aspect of current control, achieving precise gradation implementation without requiring a single complex circuit to handle all functions simultaneously.
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 solution enables accurate gradation implementation without wavelength shifts, improving display quality by stabilizing current density and enhancing light-emitting time control.
Implementation Method 1
a first capacitor connected between a sweep line and a first node
Implementation Method 2
a second capacitor connected between a fourth node and a fifth node
Implementation Method 3
a light-emitting element
Data Source
AI summary
A pixel includes: a first power line configured to receive a first initialization power supply voltage configured to swing between a first voltage and a second voltage; a light-emitting element; a first circuit configured to control a supply period of a driving current in response to a data signal supplied from a data line; and a second circuit configured to supply the driving current corresponding to a difference voltage of the first voltage and the second voltage to the light-emitting element.