Light Emitting Display Driving Method Stabilizing Luminance
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Solution Overview
Problem
Conventional light emitting display devices face challenges in maintaining a constant voltage level, leading to unstable luminance and potential display quality issues due to overlapping signal timing and voltage fluctuations across pixel rows.
Innovation Solution
The proposed light emitting display device incorporates a specific configuration of transistors and capacitors, including a driving transistor, data and bias transistors, and initialization transistors, with optimized timing and frequency control to maintain a constant voltage level across pixels, ensuring stable luminance by overlapping certain initialization sections and applying signals in a manner that reduces crosstalk and voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the third transistor and fourth transistor are turned on at different timings, then the voltage control is simpler, but the luminance stability deteriorates due to voltage fluctuations
Solution Approach 1:
The patent merges the operation timing of the third transistor (connecting drain and gate electrodes) and the fourth transistor (initializing gate electrode) by making their active periods overlap. This simultaneous operation stabilizes the gate electrode voltage during initialization and data writing, preventing luminance instability caused by voltage fluctuations, while maintaining a manageable transistor control structure.
Solution Approach 2:
The patent applies preliminary action by initializing the gate electrode voltage before data writing operations. The fourth transistor activates the initialization voltage in advance, ensuring the gate electrode is properly prepared and stabilized before the third transistor connects the drain and gate for data writing, thereby preventing voltage fluctuations during subsequent operations.
2Speed
If the initialization section and data writing section are separated completely, then the voltage control is more stable, but the display refresh speed deteriorates
Solution Approach 1:
The patent combines the initialization section and data writing section by overlapping their timing. The third transistor and fourth transistor are activated simultaneously, allowing initialization and data writing to proceed in parallel. This merging of sections accelerates the display refresh speed without compromising voltage stability, as the gate electrode voltage is maintained constant throughout the overlapping period.
3Productivity
If the signal timing is optimized for speed, then the display refresh rate increases, but the voltage fluctuations increase causing display quality issues
Solution Approach 1:
The patent applies preliminary action by stabilizing the gate electrode voltage through the fourth transistor's initialization operation before the data writing operation begins. This preliminary voltage stabilization ensures that subsequent fast data writing operations do not cause voltage fluctuations that would degrade display quality, thereby achieving high refresh rates with maintained display quality.
Solution Approach 2:
The patent merges the timing of voltage stabilization and data writing operations by overlapping the active periods of the third and fourth transistors. This merging allows the system to achieve high display refresh rates while maintaining voltage stability, as the gate electrode voltage is continuously controlled throughout the combined operation period, preventing quality-degrading fluctuations.
Data Source
AI summary
A display device includes the following elements: a light emitting diode; a first transistor including a drain electrode, a source electrode, and a gate electrode, the drain electrode being connected to the light emitting diode; a second transistor connected between a data line and the source electrode; a third transistor connected between the drain electrode and the gate electrode; and a fourth transistor connected between a first initialization voltage source and the gate electrode. The third transistor is off for a first period, on for a second period immediately following the first period, and off for a third period immediately following the second period. The fourth transistor is off for a fourth period, on for a fifth period immediately following the fourth period, and off for a sixth period immediately following the fifth period. The second period overlaps the fifth period.