OLED Driving Circuit Threshold Compensation and Light Emission Control
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Solution Overview
Problem
Existing display devices using the simultaneous light emitting method face challenges in extending the light emitting time of pixels due to the complexity of signal control and the limited duration of the light emitting period, which is about 42% of the total display time.
Innovation Solution
A display device and driving method that apply a first voltage to the anode of OLEDs, diode-connect driving transistors to compensate threshold voltage, and change the second power source voltage to a logic low level to enable simultaneous light emission from pixels, simplifying signal control and expanding the light emitting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a simultaneous light emitting method is used to expand light emitting time, then the light emitting duration increases, but the signal control complexity increases
Solution Approach 1:
The patent segments the driving waveform into distinct voltage levels (first voltage level for anode, second voltage level for cathode) and applies them at different time periods (light emitting period, reset period, threshold voltage compensation period). This segmentation simplifies the control signals by using discrete voltage states rather than continuous modulation, thereby expanding light emitting time while maintaining manageable signal control complexity.
Solution Approach 2:
The patent implements periodic action by cycling through distinct driving periods (light emitting period, reset period, threshold voltage compensation period) in a repeating sequence. Each period applies specific voltage levels to achieve different functions, allowing the display device to maintain expanded light emitting time through systematic periodic waveform control rather than complex continuous signaling.
2Manufacturing precision
If a complicated driving method with variable control signals is used to achieve precise pixel control, then the display quality improves, but the light emitting period becomes insufficient
Solution Approach 1:
The patent changes the voltage level parameters of the driving signals to achieve precise pixel control. By applying a first voltage level to the anode and a second voltage level to the cathode during the light emitting period, the patent maintains precise control over pixel activation while extending the light emitting duration. The parameter changes in voltage levels replace the need for complicated variable control signals, thereby resolving the contradiction between control precision and light emitting period duration.
3Reliability
If additional reset periods and threshold voltage compensation periods are included to ensure proper pixel operation, then the display reliability improves, but the light emitting time decreases
Solution Approach 1:
The patent performs preliminary actions by conducting reset operations and threshold voltage compensation during dedicated periods before the light emitting period begins. The reset period initializes pixel states, and the threshold voltage compensation period adjusts for voltage variations, both preparing the pixels for optimal light emission. By completing these preliminary actions beforehand, the patent ensures display reliability while maximizing the subsequent light emitting time.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that the light emitting period immediately follows the threshold voltage compensation period without interruption. The systematic sequencing of periods (reset → threshold voltage compensation → light emitting) creates a continuous operational cycle where each phase prepares for the next, maximizing the proportion of time dedicated to light emission while maintaining necessary preparatory operations for reliability.
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 method simplifies signal control and extends the light emitting time of pixels, allowing for more efficient image display without the need for additional reset periods, thereby improving the display performance of large-sized panels.
Implementation Method 1
a plurality of organic light emitting diodes (OLEDs) included in a plurality of pixels
Data Source
AI summary
A driving method of a display device is disclosed. According to one aspect, the method includes applying a first voltage of a predetermined level to an anode of a plurality of organic light emitting diodes (OLEDs) included in a plurality of pixels. A plurality of driving transistors are driven to be connected to the plurality of OLEDs. The method further includes transmitting a first power source voltage of a logic high level to the anode of the plurality of OLEDs as a threshold voltage to compensate a threshold voltage of the plurality of driving transistors, and applying a data voltage to a plurality of pixels as a data writing step turning on a plurality of driving transistors. The second power source voltage applied to the cathode of the plurality of OLEDs is changed to a second voltage of the logic low level in a state in which a plurality of driving transistors are turned on. In the turned on state, light is emitted from the plurality of OLEDs.