Display Driver Adaptive Parking Voltage Leakage Current
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Solution Overview
Problem
In electroluminescent display devices using variable refresh rate (VRR) mode, leakage current occurs in data supply transistors during the hold frame, leading to image quality deterioration due to prolonged off-state, caused by electric potential differences between source and drain electrodes.
Innovation Solution
A display driver system that adaptively controls and supplies a parking voltage based on the luminance value of input data to prevent leakage current, including a controller that outputs current luminance and power supplier with a register storing mapped parking voltages, ensuring the data supply transistor remains in an off-state without current flow during the hold frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the data supply transistor maintains the off-state for a long time during the hold frame to reduce power consumption, then power consumption is reduced, but leakage current occurs between source and drain electrodes causing image quality deterioration
Solution Approach 1:
The patent applies preliminary action by establishing a parking voltage before the hold frame begins. The parking voltage is prepared in advance and stored in a register, then automatically supplied to the data supply transistor at the start of the hold frame. This preliminary preparation eliminates the need for complex real-time detection and control during the hold frame, while effectively preventing leakage current through the pre-established voltage balance between source and drain electrodes.
2Reliability
If a fixed parking voltage is supplied to prevent leakage current during the hold frame, then leakage current is prevented, but power consumption increases due to continuous voltage supply
Solution Approach 1:
The patent implements dynamics by transitioning from a fixed parking voltage to an adaptive parking voltage that varies based on the luminance value of the input data. The system dynamically adjusts the parking voltage magnitude according to the actual display requirements, supplying higher voltages only when necessary (high luminance conditions) and lower voltages when not needed (low luminance conditions). This dynamic adaptation maintains effective leakage current prevention while significantly reducing unnecessary power consumption during low-luminance hold frames.
3Stability of the object's composition
If the data supply transistor is kept in off-state during hold frame to maintain data voltage, then data voltage is maintained, but electric potential difference between source and drain electrodes causes leakage current
Solution Approach 1:
The patent applies equipotentiality by supplying a parking voltage to the data supply transistor during the hold frame that equalizes the electric potential between the source and drain electrodes. The parking voltage is specifically designed to match the data voltage level, creating an equipotential condition where no voltage difference exists across the transistor channels. This eliminates the driving force for leakage current while maintaining the data voltage stability, effectively resolving the contradiction between data maintenance and leakage prevention.
Data Source
AI summary
The present disclosure relates to a display driver and a display device using the same. The display device according to the embodiment improves an effect of preventing leakage current of a data supply transistor by adaptively controlling and supplying, on the basis of a luminance value of an input data, a parking voltage which is applied in order to prevent the leakage current of the data supply transistor. The display driver comprises a controller which provides a clock signal swinging between a high level and a low level during a refresh frame in which a data voltage is written in a pixel, and provides a clock signal having a direct current voltage during a hold frame in which the data voltage written in the pixel is maintained; a data driver which supplies the data voltage to the pixel during the refresh frame in accordance with a data control signal of the controller; and a power supplier which supplies a parking voltage to the pixel during the hold frame.