OLED Driving Circuit Hysteresis Compensation via Resetting Signal
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Solution Overview
Problem
Traditional OLED display devices suffer from image retention due to the hysteresis effect in transistors, which affects display quality when transitioning between high and low gray scale images.
Innovation Solution
A display device with a driving circuit that includes a switch module and a capacitor, where a periodically varied resetting signal is used to reset the voltage of the control terminal of the second switch during the first switch is turned off, allowing current to flow through the OLED along a single current-voltage characteristic curve, compensating for the hysteresis effect and preventing image retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional 2T1C driving circuit is used to control OLED brightness, then the circuit structure is simple, but image retention occurs due to hysteresis effect in transistors
Solution Approach 1:
The patent applies preliminary action by resetting the voltage of the control terminal of the second switch before the OLED emits light. The resetting signal is applied in advance during the period when the first switch is turned off, ensuring that the transistor starts from a known voltage state before current flows through the OLED, thereby preventing hysteresis-induced image retention.
Solution Approach 2:
The patent implements periodic action by applying resetting signals at regular intervals corresponding to each frame or sub-frame period. The resetting signal is periodically applied to the control terminal of the second switch, synchronizing with the display refresh rate, to continuously counteract the hysteresis effect and maintain consistent current-voltage characteristics.
2Ease of operation
If hysteresis effect is present in the transistor, then the transistor can function as a switch, but different currents are generated for the same data signal depending on previous states
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage parameter of the control terminal of the second switch. By applying resetting signals that change the voltage state of the control terminal, the transistor's electrical characteristics are modified to eliminate hysteresis, ensuring that the same data signal always produces the same current regardless of previous states.
3Duration of action of stationary object
If the voltage of the control terminal is not reset periodically, then the circuit operation is continuous, but image retention accumulates over time
Solution Approach 1:
The patent converts the potentially harmful hysteresis effect into a beneficial reset mechanism. By intentionally applying resetting signals that temporarily alter the voltage state, the system actively counteracts the hysteresis buildup, transforming what would be a harmful accumulation effect into a controlled reset process that maintains display quality over continuous operation.
Data Source
AI summary
The present invention provides a display device, a displaying method thereof and a driving circuit for current-driven device. Each pixel of the display device includes a current-driven device and a driving circuit. A first terminal of the current-driven device is electrically coupled to a first preset voltage. The driving circuit includes a switch module and a capacitor. The switch module is electrically coupled to a data signal, a second terminal of the current-driven device and a second preset voltage. The switch module is for determining whether a current is allowed to flow through the current-driven device and setting a value of the current according to the data signal. The capacitor is electrically coupled between a periodically changed resetting signal and the switch module, to couple the resetting signal into the switch module to reset a voltage at a connection node between the capacitor and the switch module.