Display Device PSR Mode Flicker Reduction via Blanking Period Adjustment
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Solution Overview
Problem
Display devices with Panel Self Refresh (PSR) function experience degraded display quality due to flicker caused by asynchronous frame data output and reduced drive frequency, leading to increased blanking periods and display luminance differences when switching between PSR and normal modes.
Innovation Solution
A display device with a processor that calculates and adjusts the blanking period by adjusting the vertical retrace period, horizontal retrace period, or clock frequency, and interpolates image data during extended blanking periods to maintain consistent display luminance, thereby reducing flicker and improving display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drive frequency is reduced to lower power consumption in PSR mode, then energy efficiency is improved, but display quality deteriorates due to increased blanking period and luminance difference
Solution Approach 1:
The patent dynamically adjusts the drive frequency based on the type of image content being displayed. For static images, a lower drive frequency is used to reduce power consumption, while for moving images, a higher drive frequency is applied to maintain display quality. This parameter change resolves the contradiction by adapting the energy consumption level to the actual display requirements.
Solution Approach 2:
The system transitions between different drive frequency states (low frequency for PSR mode with static images, high frequency for normal mode with moving images) based on real-time detection of image content and mode switching. This dynamic adjustment allows the display device to optimize power consumption while maintaining acceptable display quality across different operating conditions.
2Use of energy by moving object
If frame data output is stopped in PSR mode to reduce power consumption, then energy efficiency is improved, but display quality deteriorates due to asynchronous timing and flicker
Solution Approach 1:
The control circuit continuously monitors the timing relationship between the PSR mode frame data and the normal mode frame data, and detects when asynchronous timing causes blanking period extension. Based on this feedback, the system adjusts the timing of frame data output to prevent excessive blanking periods, thereby eliminating flicker while maintaining the power-saving benefits of PSR mode.
Solution Approach 2:
The control circuit proactively adjusts the timing parameters before switching between PSR and normal modes to prevent asynchronous timing issues. By pre-synchronizing the frame data output timing and adjusting the blanking period in advance, the system avoids flicker and display quality degradation while maintaining energy efficiency.
3Adaptability or versatility
If the blanking period is extended due to asynchronous timing, then timing flexibility is improved, but display quality deteriorates due to increased luminance difference and flicker
Solution Approach 1:
The system dynamically adjusts the blanking period duration based on the detected timing relationship between PSR and normal mode frame data. When asynchronous timing is detected, the blanking period is extended only by the necessary minimum amount required to maintain synchronization, rather than allowing excessive extension. This parameter adjustment maintains timing flexibility while preventing display quality degradation from excessive blanking periods.
Data Source
AI summary
A display device including a processor that includes a first display mode in which the processor displays the image on the display screen; and a second display mode in which the processor displays the image on the display screen from the image data received by the processor. The display device further includes a calculator that calculates a blanking period between a writing end time point of the internal image data corresponding to a final frame immediately before switching from the first display mode to the second display mode and a writing start time point of the image data corresponding to an initial frame immediately after switching from the first display mode to the second display mode, and an adjuster that adjusts at least one of a vertical retrace period, a horizontal retrace period, and a clock frequency, which correspond to the internal image data, depending on the blanking period.