OLED Display Leakage Current Cut-Off Unit
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Solution Overview
Problem
Organic light emitting diode display devices face issues with leakage current during sleep mode due to uncut battery power, leading to increased power consumption and reduced efficiency.
Innovation Solution
Incorporating a leakage current cut-off unit with PMOS and NMOS switches controlled by a current path control signal to block the current path between the power supply unit and the display unit, and using a pull-down resistor to ensure the NMOS switch is turned off, even during initialization stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power IC excludes the true shutdown function to reduce power consumption and increase efficiency, then power consumption is reduced and efficiency is increased, but leakage current cannot be cut off when the display unit is in disable state
Solution Approach 1:
The patent introduces a second NMOS switch (NMT2) as an intermediary component between the power IC and display unit. This switch is controlled by a current path control signal (CTS) from the driving unit to selectively block the current path. When the display unit is in disable state, NMT2 turns off to cut off leakage current, while allowing normal operation when enabled. This mediator resolves the contradiction by providing leakage current cut-off capability without requiring modification to the power IC's internal shutdown function.
2Loss of energy
If the second NMOS switch is added to cut off leakage current, then leakage current is blocked, but device complexity increases
Solution Approach 1:
The second NMOS switch (NMT2) is designed to serve multiple functions: it acts as a leakage current cut-off switch during disable state, and can be integrated with the existing output buffer structure. The switch shares the current path control mechanism with other switches in the system, allowing a single component to address leakage current issues while working within the existing multi-switch architecture of the display driver.
3Loss of energy
If the gate block of switches is in floating state during sleep mode, then power consumption is reduced, but leakage current may flow during initialization stage
Solution Approach 1:
The patent implements preliminary control by generating the current path control signal (CTS) in advance to anticipate when leakage current might occur. During the initialization stage, even though the gate blocks are in floating state to save power, the CTS signal is prepared and applied to the second NMOS switch to prevent leakage current before it can flow through the pixel circuit. This preliminary action ensures leakage prevention without requiring the gate blocks to remain actively controlled.
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
Effectively cuts off leakage current in sleep mode, reducing power consumption and enhancing efficiency by ensuring no current flows when the power IC is disabled, as demonstrated by simulation results showing zero leakage current in all cases.
Implementation Method 1
Incorporating a leakage current cut-off unit with PMOS and NMOS switches controlled by a current path control signal to block the current path between the power supply unit and the display unit
Implementation Method 2
using a pull-down resistor to ensure the NMOS switch is turned off, even during initialization stages
Data Source
AI summary
An organic light emitting display device according to the present invention comprises a display unit; a power supply unit; a driving unit including an output buffer generating the reference voltage and applying the reference voltage to the pixels, and generating a current path control signal in a different logic level along with controlling whether to operate the power IC according to an operating mode; and a leakage current cut-off unit switching a current path between the output terminal of the power supply unit and the input terminal of the OLED driving voltage according to the current path control signal.