Display Device Afterimage Prevention via Reverse Grayscale Compensation
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Solution Overview
Problem
Display devices experience afterimages due to long-term display of fixed images, particularly in areas showing logos, times, or subtitles, leading to pixel degradation and intensified afterimages.
Innovation Solution
A display device and driving method that include a display panel with pixels connected to scan and data lines, utilizing a scan driver to supply first and second scan signals and a data driver to supply first and second data signals, where the second data signal is generated by reversing the grayscale of input image data to prevent pixel threshold voltage changes, and an emission driver controls emission periods to minimize afterimage occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the same image is displayed on the display panel for a long time, then the display function is maintained, but pixels become degraded and afterimage occurs
Solution Approach 1:
The patent applies periodic action by dividing the display frame into multiple periods: a normal display period for showing the original image and a compensation period for applying reverse grayscale values. This periodic switching between normal and compensated display modes prevents pixel degradation by periodically resetting pixel threshold voltages, thereby maintaining reliable display function over extended durations.
Solution Approach 2:
The patent implements preliminary action by performing compensation in advance before severe pixel degradation occurs. During the compensation period, reverse grayscale values are applied to pixels that have been displaying the same image, proactively counteracting threshold voltage shifts before they lead to visible afterimages or permanent damage.
2Reliability
If a compensation period is added to display reversed grayscale data, then afterimage is reduced, but the frame length and complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the display frame into distinct segments: a normal display period for regular image content and a separate compensation period for applying reverse grayscale. This segmentation allows the compensation function to be isolated and managed independently, reducing overall system complexity while maintaining effective afterimage prevention.
Solution Approach 2:
The compensation period is structured as a preliminary action phase that prepares pixels for the next normal display period. By pre-compensating pixel threshold voltages during the compensation period, the system simplifies the main display period and avoids the need for complex real-time adjustment mechanisms during normal operation.
3Reliability
If the supply timing of the second scan signal varies, then compensation effectiveness is improved, but control complexity increases
Solution Approach 1:
The patent implements dynamics by making the supply timing of the second scan signal variable rather than fixed. The compensation period timing can be dynamically adjusted based on display conditions, such as the duration of fixed image display or detected pixel degradation levels. This dynamic timing optimization enhances compensation effectiveness while the underlying periodic structure maintains control simplicity.
Data Source
AI summary
A display device includes: a display panel including a plurality of pixels, a pixel from among the pixels being coupled to a scan line and a data line; a scan driver configured to supply a first scan signal to the scan line in a scan period in one frame, and to supply a second scan signal to the scan line in a compensation period after the scan period; and a data driver configured to supply a first data signal to the data line in synchronization with the first scan signal, and to supply a second data signal to the data line in synchronization with the second scan signal, wherein the first data signal is generated based on input image data supplied from an image source, and the second data signal is generated based on a conversion image data obtained by converting a grayscale of the input image data.