Display Device Gamma Voltage Feedback for Aging Transistors
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Solution Overview
Problem
Thin film transistors in display devices gradually age, leading to insufficient charging of sub-pixels and a decrease in brightness over time, affecting the service life of the device.
Innovation Solution
Incorporation of a detection resistor and detection transistor to monitor the aging of driving transistors, with a control circuit adjusting the gamma voltage output to maintain consistent brightness by increasing the voltage across driving transistors as their impedance increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If thin film transistors are used to drive sub-pixels in display devices, then high responsivity and high brightness are achieved, but the transistors gradually age with long term use leading to insufficient charging of sub-pixels and dark display
Solution Approach 1:
The patent implements a feedback mechanism by introducing a detection transistor and detection resistor that continuously monitor the voltage across the driving transistor. When the voltage drops below a threshold (indicating transistor aging), the system automatically adjusts the gamma voltage to compensate, thereby maintaining brightness and extending the effective service life of the display device.
Solution Approach 2:
The patent changes the gamma voltage parameter dynamically based on the detected voltage level across the driving transistor. By adjusting the gamma voltage in response to transistor aging, the system maintains consistent charging current to sub-pixels, preventing brightness degradation over time.
2Illumination intensity
If detection transistor and detection resistor are added to monitor aging, then brightness consistency is maintained, but device complexity increases
Solution Approach 1:
The detection transistor is designed with the same structure as the driving transistor, allowing it to serve dual purposes: monitoring the driving transistor's voltage while potentially serving as a replacement driving transistor when needed. This multi-functionality reduces the need for entirely separate monitoring components.
Solution Approach 2:
The detection resistor serves as an intermediary element that converts the voltage change across the driving transistor into a measurable voltage signal. This intermediary approach allows indirect monitoring of transistor aging without requiring direct measurement of the driving transistor's internal state, simplifying the detection mechanism.
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
Effectively prevents dimming of the display due to long-term use by ensuring consistent charging current to sub-pixels, thereby extending the device's service life.
Implementation Method 1
a detection resistor having a first terminal and a second terminal for electrical connection, wherein the first terminal is grounded... a second electrode of the detection transistor is electrically connected to the second terminal of the detection resistor
Implementation Method 2
controls the gamma chip to increase the output of the gamma voltage when a voltage of the detection resistor decreases, such that the voltage of the first electrode of each driving transistor can be increased when the impedance of the driving transistor increases due to its aging
Data Source
AI summary
A display device, comprising: a power supply chip configured to output a gate-on voltage; a gamma chip configured to output a gamma voltage; a detection resistor having a first terminal and a second terminal, wherein the first terminal is grounded; a display panel comprising a plurality of sub-pixels, a plurality of driving transistors, and at least one detection transistor; a control circuit electrically connected to the second terminal of the detection resistor, and configured to control the gamma chip to increase the output of the gamma voltage when a voltage of the detection resistor decreases.