Display Power Supply Control via Refresh Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display power supply technologies face issues with output voltage variance leading to flicker and brightness variation, especially under low power consumption conditions, and struggle to efficiently manage switching time to maintain reference voltage, while also causing visible stripes in images due to low switching frequencies.
Innovation Solution
A power supply control method that includes an output capacitor and a control unit which charges the capacitor during non-refreshing periods and stops charging during refreshing periods, utilizing both PWM and PFM control modes to optimize charging based on output power levels and blanking periods, thereby reducing power consumption and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply uses traditional PFM control mode with low switching frequency to save power, then power consumption is reduced, but visible stripes appear in the displayed image
Solution Approach 1:
The patent applies periodic action by synchronizing the DC/DC converter switching cycles with the display's refresh rate. The converter is configured to complete a predetermined number of switching cycles corresponding to the refresh rate, ensuring that power conversion operations are periodically aligned with display updates. This synchronization prevents visible stripes by ensuring that voltage variations occur during non-display periods or are smoothed out before reaching the display, while still allowing the converter to operate at lower frequencies for power savings.
2Stability of the object's composition
If the switching time of the power supply is restricted to maintain reference voltage, then output voltage stability is improved, but the switching frequency decreases causing visible stripes
Solution Approach 1:
The patent applies preliminary action by pre-configuring the DC/DC converter to operate in synchronization with the display refresh rate before actual display operations begin. The converter is set up to complete a predetermined number of switching cycles that correspond to the refresh rate, ensuring that voltage stabilization occurs in advance and during non-display periods. This preliminary synchronization prevents visible stripes while maintaining output voltage stability.
3Power
If the DC/DC converter operates independently without coordinating with display refresh signals, then conversion efficiency is maintained, but switching noise interferes with display refresh
Solution Approach 1:
The patent applies feedback by receiving refresh rate information from the display and using it to dynamically adjust the DC/DC converter's switching cycles. The converter is configured to complete a predetermined number of switching cycles based on the received refresh rate, creating a feedback loop where the display's operational state directly influences the power conversion timing. This ensures that switching noise is synchronized with and does not interfere with display refresh operations, while maintaining conversion efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach stabilizes the output voltage, reduces brightness variation, minimizes noise, and decreases power consumption by optimizing charging during vertical and horizontal blanking periods, thus enhancing display performance and reducing visible stripes.
Implementation Method 1
an output capacitor and a control unit, wherein the output capacitor provides an output voltage to the pixel driving unit
Implementation Method 2
The control unit controls the power supply to charge the output capacitor when the pixels are not being refreshed and to stop charging the output capacitor when the pixels are being refreshed
Data Source
AI summary
A display includes a display panel, a pixel driving unit and a power supply for supplying power to the pixel driving unit. The display panel includes a plurality of pixels arranged in a matrix manner. The pixel driving unit is used for driving the pixels. The power supply includes an input power source, an output capacitor for providing an output voltage, and a control unit for controlling the input power source, such that in a frame period, the input power source charges the output capacitor during the non-refreshing duration of the pixels by the input power source and stops charging the output capacitor during the refreshing duration of the pixels.