Dual-Gate Pixel Driving Circuit for Luminance Stability
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Solution Overview
Problem
Display devices face challenges in maintaining consistent luminance during light emission periods due to leakage currents in transistors, leading to variations in gate voltage and reduced luminance expression.
Innovation Solution
A display device with a pixel structure including a light emitting element, a driving transistor with a dual gate structure, and a driving circuit that controls the gate voltage by dividing the light emission period into sub-periods and supplying control signals with varying voltages to maintain uniform luminance, using a lookup table to store voltage information for different driving frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a constant gate voltage is applied to the driving transistor during the light emission period, then the circuit structure is simple, but the luminance varies due to leakage current in the transistor
Solution Approach 1:
The light emission period is divided into multiple sub-periods, and the gate voltage is adjusted separately in each sub-period. This segmentation allows the system to compensate for leakage current effects that accumulate over time, maintaining stable luminance without requiring a completely complex control system.
Solution Approach 2:
The gate voltage is periodically adjusted during the light emission period by dividing it into sub-periods. This periodic action counteracts the cumulative effect of leakage current, which would otherwise cause continuous drift in luminance, thereby maintaining stability without constant voltage adjustment.
2Stability of the object's composition
If the light emission period is divided into multiple sub-periods with varying control signals, then luminance uniformity is improved, but the control signal complexity increases
Solution Approach 1:
The light emission period is segmented into multiple sub-periods, allowing different control signals to be applied in each segment. This segmentation enables targeted compensation for leakage current at different time intervals, achieving uniform luminance while keeping each individual control signal relatively simple.
Solution Approach 2:
The gate voltage parameter is changed across different sub-periods to compensate for leakage current effects. By adjusting the voltage parameter in a controlled manner across sub-periods, the system achieves luminance uniformity without requiring overly complex control signals.
3Use of energy by moving object
If the driving frequency is reduced to lower power consumption, then energy efficiency is improved, but luminance stability deteriorates due to longer light emission periods
Solution Approach 1:
Even at lower driving frequencies with longer light emission periods, the period is segmented into multiple sub-periods. This allows the system to maintain luminance stability throughout the extended period by applying corrective control signals at appropriate intervals, thus achieving both low power consumption and stable luminance.
Solution Approach 2:
Periodic control signal adjustment is applied during the extended light emission period at lower frequencies. This periodic action prevents luminance drift caused by accumulation of leakage current over longer periods, enabling the system to operate at lower frequencies without sacrificing luminance stability.
Data Source
AI summary
A display device includes: a pixel including: a light emitting element connected between a first power source and a second power source; a first transistor connected between the first power source and the light emitting element to control a driving current, and including a first gate electrode connected to a first node and a second gate electrode connected to a bias control line; and a switching transistor connected between a data line and the first node, and including a gate electrode connected to a scan line; and a driving circuit to drive the pixel according to a driving frequency. The driving circuit drives the pixel in a first mode when the driving frequency is in a first range, and sequentially supplies a control signal having a first voltage and a second voltage to the bias control line during a light emission period of the pixel in the first mode.