OLED Display Power Control for Flicker-Free Mode Transitions
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Solution Overview
Problem
Organic light emitting diode (OLED) displays experience rapid changes in luminance when transitioning from a low power mode to a normal mode due to changes in pixel driving voltage, leading to potential user perception of screen flicker and potential battery voltage drops.
Innovation Solution
An OLED display system that includes a power generator to provide a first voltage for normal operation and a second, lower voltage for low power mode, with a panel driving circuit that synchronizes the power generator's enablement with the vertical blank period during mode changes, and adjusts the high potential power voltage difference between modes to minimize luminance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pixel driving voltage is increased to display high luminance in normal mode, then the luminance is improved, but the power consumption increases and causes rapid luminance changes during mode transition
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor during the vertical blank period before the image signal is displayed. This ensures that when the pixel driving voltage increases from low power mode to normal mode, the capacitor is already charged and ready to maintain stable luminance, preventing rapid luminance changes while allowing the voltage to be increased for high luminance display
Solution Approach 2:
The patent introduces a capacitor as an intermediary element that mediates between the pixel driving voltage and the OLED. The capacitor stores electrical energy and releases it during mode transitions, acting as a buffer that smooths out voltage changes and prevents direct transmission of voltage fluctuations to the OLED, thereby stabilizing luminance during power mode transitions
2Use of energy by moving object
If the pixel driving voltage is reduced to decrease power consumption in low power mode, then the power consumption is reduced, but the luminance decreases and causes rapid luminance changes during mode transition
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor during the vertical blank period before switching from low power mode to normal mode. This ensures that when the pixel driving voltage needs to increase, the capacitor is already prepared with stored energy, enabling smooth transition without rapid luminance changes while maintaining low power consumption during the low power mode operation
Solution Approach 2:
The capacitor serves as an intermediary that decouples the OLED from direct voltage fluctuations. During low power mode, it allows reduced voltage for lower power consumption, and during mode transitions, it buffers the voltage changes to prevent luminance instability, thus mediating between power consumption reduction and luminance maintenance
3Speed
If the mode transition is made quickly to improve responsiveness, then the responsiveness is improved, but rapid luminance changes occur causing screen flicker
Solution Approach 1:
The patent applies preliminary action by utilizing the vertical blank period to pre-charge the capacitor before the actual mode transition occurs. This allows the system to respond quickly to mode change commands while ensuring that all necessary electrical preparations are completed beforehand, enabling fast transitions without luminance instability or screen flicker
Solution Approach 2:
The capacitor acts as an intermediary that absorbs and smooths voltage fluctuations during mode transitions. By placing the capacitor between the voltage source and the OLED, it filters out rapid voltage changes that would otherwise cause luminance instability, allowing fast mode transitions to occur without producing visible screen flicker
Data Source
AI summary
An organic light emitting diode (OLED) display includes a display panel including data lines, scan lines crossing the data lines, and pixels which each include an organic light emitting diode and are arranged in a matrix form, a power generator which is enabled in a normal mode to generate a high potential power voltage for driving the display panel and is disabled in a low power mode, and a panel driving circuit which drives the data lines and the scan lines, disables the power generator in the low power mode to cut off an output of the power generator, and supplies an internal power less than the high potential power voltage to the display panel to reduce the high potential power voltage in the low power mode.