Display Drive Method Adjusting Threshold Voltage Cancel Duration
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Solution Overview
Problem
Display devices using organic electroluminescence face challenges in maintaining consistent video signal values across varying frame frequencies, leading to residual image effects and inefficient black display performance.
Innovation Solution
A drive method for display devices that adjusts the duration of threshold voltage cancel processing based on frame frequency, ensuring consistent potential differences between nodes and thus stabilizing video signal values without requiring adjustments to the video signal itself.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the duration of threshold voltage cancel processing is extended to ensure consistent potential differences, then video signal stability improves, but the display refresh efficiency deteriorates at higher frame frequencies
Solution Approach 1:
The patent applies dynamics by making the threshold voltage cancel processing duration variable rather than fixed. The processing duration is dynamically adjusted based on the frame frequency: at lower frame frequencies (e.g., 60Hz), the processing lasts longer to ensure thorough threshold voltage cancellation and consistent video signal values; at higher frame frequencies (e.g., 120Hz), the processing duration is shortened to maintain display refresh efficiency. This dynamic adaptation resolves the contradiction between reliability and productivity.
Solution Approach 2:
The patent changes the temporal parameter of threshold voltage cancel processing based on operating conditions. Specifically, the duration parameter is modified according to frame frequency requirements, allowing the system to optimize between complete threshold voltage cancellation (for signal consistency) and time efficiency (for refresh performance). This parameter adjustment strategy enables the display device to maintain video signal stability across varying frame frequencies without compromising overall display performance.
2Speed
If frame frequency is increased to reduce residual image effects, then motion display quality improves, but video signal value consistency deteriorates
Solution Approach 1:
The patent employs dynamics by adapting the threshold voltage cancel processing duration to match the frame frequency. When operating at higher frame frequencies where residual image reduction is prioritized, the processing duration is optimized to provide sufficient threshold voltage cancellation without excessively lengthening the refresh cycle. This dynamic adjustment ensures that video signal values remain consistent even at higher speeds, resolving the contradiction between motion display quality and signal consistency.
3Ease of operation
If threshold voltage cancel processing is performed for fixed duration, then circuit operation simplicity is maintained, but display performance varies across different frame frequencies
Solution Approach 1:
The patent transforms the fixed-duration threshold voltage cancel processing into a dynamic, adaptive process. The processing duration is adjusted based on the detected or configured frame frequency, allowing the circuit to maintain optimal performance across different operating conditions. This dynamic approach enhances adaptability while preserving operational simplicity through automated duration selection based on frame frequency parameters.
Solution Approach 2:
The patent modifies the temporal parameter of threshold voltage cancel processing according to frame frequency requirements. By changing the duration parameter dynamically, the circuit achieves compatibility across various frame frequencies (e.g., 60Hz, 120Hz, 240Hz) without requiring complex circuit redesign. This parameter adaptation maintains ease of operation while significantly improving frame frequency versatility.
Data Source
AI summary
A drive method of a display device includes the steps of: performing threshold voltage cancel processing at least once, which changes a potential of a second node of a display device toward a potential obtained by subtracting a threshold voltage of a drive transistor from a potential of a first node by applying a given drive voltage to one source/drain region of the drive transistor from a feeding line while maintaining the potential of the first node; and then, performing writing processing which applies a video signal to the first node from a data line through a write transistor, wherein the sum of lengths of periods in which the threshold voltage cancel processing is performed is so set as to be shorter as a frame frequency becomes higher.