OLED Flash Suppression via Reset Potential Sequencing
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Solution Overview
Problem
The flash phenomenon occurs in organic electroluminescence (OLED) display devices when the main power source is turned on, causing unintended light emission and brightness changes, due to uncontrolled potential differences and coupling between power source lines and internal nodes.
Innovation Solution
A display device and driving method that includes a light emitting element, a driving transistor, switching elements, and a control unit to manage power source sequences, where the switching elements are controlled to block connections and apply reset potentials before main power source activation, setting a preset state to prevent unintended light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the main power source is turned on rapidly, then the display device can start operating quickly, but unintended light emission occurs causing flash phenomenon
Solution Approach 1:
The patent applies preliminary action by setting the switching elements to specific states (first switching element OFF, second switching element ON) before the power source lines are activated. This preliminary configuration ensures that even when power is rapidly applied, the OLEDs are protected from unintended light emission because the circuit path is controlled in advance, thus resolving the flash phenomenon while maintaining fast startup.
2Productivity
If the first switching element is kept ON to allow current flow, then the OLED can emit light normally, but unintended light emission occurs at power source ON
Solution Approach 1:
The patent uses preliminary action by pre-configuring the switching elements before power application. The first switching element is set to OFF state and the second switching element to ON state beforehand, creating a safe initial state that prevents unintended light emission while allowing normal operation to commence once the power stabilizes.
Solution Approach 2:
The patent introduces the second switching element as an intermediary between the power source line and the OLED anode. This intermediary component allows controlled connection - it can be turned ON to supply power without causing unintended light emission (when first switching element is OFF), and turned OFF to prevent light emission when needed, thus mediating between power supply and light output.
3Object-affected harmful factors
If the switching elements are controlled to prevent flash phenomenon, then unintended light emission is suppressed, but the circuit complexity increases
Solution Approach 1:
The patent introduces the second switching element as an intermediary component that simplifies the control logic. By placing this intermediary between the power source and OLED, the system achieves flash phenomenon suppression through a clear, manageable switching sequence rather than complex multi-element coordination, making the control strategy more straightforward despite adding one component.
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
The solution effectively suppresses the flash phenomenon by maintaining the anode potential of OLEDs within a stable range, preventing unintended light emission and ensuring consistent brightness during power source ON.
Implementation Method 1
a light emitting element emitting light by applying a voltage between electrodes
Data Source
AI summary
A flash phenomenon of OLEDs at the time of power source ON of a display device is suppressed. The OLED emits light when reference potentials VSS and VDD are applied from power source lines to the OLED's cathode and anode respectively. While the anode can be connected to one of the power source line via a driving TFT and a lighting switch, a reset potential VRS can be applied to the anode via a reset switch and the driving TFT. The lighting switch is turned OFF and the reset switch and the driving TFT are turned ON so that VRS is applied to the anode, before starting the application of the reference potentials to the power source lines. Following this state, the application of the reference potentials to the power source lines starts, and thus a normal operation of allowing the OLED to emit light starts.