Double Gate Transistor OLED Display Bias Voltage Control
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Solution Overview
Problem
Organic light emitting diode (OLED) displays experience luminance deviations due to variations in driving transistor characteristics, leading to potential power consumption increases and image quality issues, particularly when driven at low frequencies.
Innovation Solution
A display device incorporating a double gate transistor, a current sensor, and a gate voltage controller that applies a bias voltage signal to one gate electrode of the double gate transistor when current changes exceed a 2% ratio from a target value, minimizing luminance changes visible to the user by compensating for current deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the display device is driven at a low frequency to reduce power consumption, then power consumption is reduced, but luminance change becomes more visible to the user
Solution Approach 1:
The patent implements a feedback mechanism where a sensor detects the actual driving frequency of the OLED display, and this detected frequency is fed back to a controller. The controller then adjusts the gate voltage of the driving transistor based on the detected frequency to compensate for luminance changes. This closed-loop feedback system allows the display to maintain stable luminance perception across different driving frequencies while consuming less power at lower frequencies.
Solution Approach 2:
The patent changes the operating parameters of the driving transistor dynamically based on the driving frequency. Specifically, the gate voltage (Vg) is adjusted according to the detected frequency - at lower frequencies, the gate voltage is increased to compensate for the reduced refresh rate and prevent visible luminance changes. This parameter adjustment allows the display to operate efficiently at low frequencies without compromising image quality.
2Manufacturing precision
If a compensation circuit is added to compensate for driving transistor characteristic deviation, then luminance deviation between pixels is reduced, but device complexity increases
Solution Approach 1:
The patent makes the existing driving transistor serve multiple functions by adding a second gate electrode to it. This modified driving transistor not only controls the current to the OLED but also responds to feedback signals for frequency-based compensation. By making the driving transistor multi-functional, the patent avoids adding separate compensation circuits that would increase device complexity, while still achieving luminance uniformity across pixels.
Data Source
AI summary
A display device and a driving method thereof are provided. The display device includes a display including a pixel including a double gate transistor and a light emitting diode, a power supply for supplying power to the display, a current sensor for sensing a current flowing in the display or in the light emitting diode, and a gate voltage controller for providing a bias voltage signal to one gate electrode of the double gate transistor.