OLED Pixel Circuit Switching Transistor Voltage Control
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Solution Overview
Problem
The existing OLED display devices with a 6T1C structure face response time delays due to deviation in initial voltage during the initializing time interval, leading to less than optimal luminous efficiency, especially when transitioning from black to white, as a short-circuit occurs between the supply voltage and reference voltage, affecting the gate terminal of the driving transistor.
Innovation Solution
Incorporating an additional transistor T5 between the supply voltage and the driving transistor to control the application of the supply voltage during initialization, using an emission control signal from a previous stage to prevent short-circuiting and uniformly apply initial sampling voltage, thereby increasing the initializing time interval and improving response characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the initializing time interval is increased to improve response characteristics, then response time is improved, but a short-circuit occurs between supply voltage and reference voltage affecting the driving transistor gate terminal
Solution Approach 1:
A fifth transistor T5 is introduced as an intermediary component between the supply voltage terminal and the driving transistor. This transistor acts as a mediator to control the application of supply voltage during the initializing time interval, preventing direct short-circuiting while enabling proper initialization sequencing.
Solution Approach 2:
The fifth transistor T5 is activated in advance during the initializing time interval to prevent the short-circuit condition before it can occur. By preemptively controlling the supply voltage application, the system avoids voltage deviation at the driving transistor gate terminal during initialization.
2Device complexity
If the 6T1C structure is used to maintain device simplicity, then device complexity is reduced, but voltage deviation occurs during initialization causing response time delays
Solution Approach 1:
The pixel circuit is segmented into distinct functional blocks with dedicated transistors for specific tasks. The fifth transistor T5 is assigned the specific function of controlling supply voltage during initialization, separating this function from other transistors to prevent interference and voltage deviation.
3Use of energy by moving object
If the supply voltage is applied during initialization to maintain luminous efficiency, then energy efficiency is improved, but short-circuiting occurs between supply voltage and reference voltage
Solution Approach 1:
The application of supply voltage to the driving transistor is made dynamic rather than static. The fifth transistor T5 dynamically controls the supply voltage application based on the initialization state, enabling luminous efficiency improvement while preventing harmful short-circuit currents through real-time switching control.
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 configuration reduces voltage deviation, enhances response characteristics, and achieves nearly complete luminous efficiency from the first frame by preventing short-circuits and uniformly applying initial voltage, thereby reducing defects like afterimages and spots.
Implementation Method 1
While the driving transistor T_dr is turned on, current flows to the OLED so that the OLED emits light. The intensity of the light emitted from the OLED is proportional to the amount of the current flowing in the OLED
Data Source
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AI summary
Disclosed herein are an OLED display panel (410) further including a switching transistor (T-SW) for controlling application of supply voltage (VDD_EL) in the initializing interval of a pixel (P), an OLED display device including the same, and a method for driving the same. The OLED display panel (410) avoids a short-circuit between supply voltage VDD_EL and reference voltage Vref to thereby reduce initialization voltage applied to the gate terminal of the driving transistor T_dr. The OLED display device can achieve various effects such as improved response characteristics of pixels by reducing deviation in the initial voltage used in sampling.