Pixel Circuit Dummy Scan Timing for Faster Display Transitions
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Solution Overview
Problem
Display devices, particularly those using LEDs, experience luminance drops and image noise during drastic scene transitions due to slow response speed, leading to noticeable image quality issues.
Innovation Solution
The implementation of a display device with a pixel circuit that includes a driving transistor, capacitors, and light emission transistors, utilizing a dummy scan signal and light emission signal to enhance response speed by pre-charging data voltage and maintaining constant luminance during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional pixel circuit without dummy signal sections is used, then the device complexity is low, but the response speed during scene transition is slow causing luminance drop
Solution Approach 1:
The patent applies preliminary action by introducing a dummy scan signal section that activates before the actual scan signal. This dummy section pre-charges the data voltage onto the pixel circuit's storage node, preparing the circuit for the upcoming scene transition. By performing this charging action in advance during the dummy period, the pixel circuit achieves faster response speed when the actual scan signal arrives, eliminating the luminance drop without requiring complex circuit restructuring.
2Manufacturing precision
If the scan signal transitions directly from low to high voltage, then the signal section is simple, but the data voltage cannot be fully charged before scan signal activation causing luminance reduction
Solution Approach 1:
The patent segments the scan signal into distinct sections: a dummy scan signal section with a first voltage level that activates early, and a driving scan signal section with a second voltage level that activates later. This segmentation allows the dummy section to provide sufficient time for data voltage charging while the driving section executes the actual pixel activation. By dividing the signal into functional segments with different voltage levels, the system achieves both adequate charging time and precise grayscale representation.
3Measurement precision
If the light emission transistor is turned on immediately with the scan signal, then the response time is short, but the data voltage is not fully charged causing inaccurate grayscale
Solution Approach 1:
The patent applies preliminary action by having the dummy scan signal section charge the data voltage onto the pixel circuit's storage node before the driving scan signal activates the light emission transistor. This ensures that when the transistor turns on, the data voltage is already fully charged, enabling accurate grayscale representation. The dummy period serves as a preparatory phase that guarantees complete voltage transfer before the emission phase begins.
Data Source
AI summary
A display device can include a light emitting element and a pixel circuit including a driving transistor; a first capacitor connected between the driving transistor and a first node; a first transistor connected between the first capacitor and a data line to operate based on a first scan signal; a first light emission transistor connected between the first capacitor and a reference voltage line to operate based on a light emission signal; and a second light emission transistor connected between the driving transistor and a low-potential voltage line to operate based on the light emission signal. The first scan signal sequentially includes a dummy scan signal section and driving scan signal section for turning on the first transistor, and the light emission signal includes a coupling period for turning on the first and second light emission transistors between the dummy scan signal section and the driving scan signal section.