Photo Element Driving Method for In-Cell Touch Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In-cell touch panels in Liquid Crystal Displays face reliability issues due to photo-induced current decay under long-term illumination, leading to reduced sensitivity and incorrect touch event determination, especially in varying environmental light conditions.
Innovation Solution
A novel photo element and driving method incorporating a compensation thin-film transistor, where a bias voltage is continuously applied to maintain the photo thin-film transistor in an open state, and high and low voltages are applied to switch and compensation transistors to prevent threshold voltage increase and photo-induced current decay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photo element is used in an in-cell touch panel, then touch sensing capability is enabled, but photo-induced current decays under long-term illumination reducing reliability
Solution Approach 1:
The patent applies a bias voltage to the photo thin-film transistor before and during illumination to pre-establish proper electrical conditions. This preliminary action prevents threshold voltage shifts that would otherwise occur during long-term illumination, thereby maintaining photo-induced current stability and reliability over extended periods
Solution Approach 2:
The patent changes the electrical parameters (voltage levels) applied to the photo thin-film transistor based on illumination conditions. By adjusting the bias voltage and switch line voltages during illumination periods, the system compensates for environmental light effects and maintains consistent photo-induced current output, preventing reliability degradation
2Productivity
If the photo thin-film transistor is continuously illuminated, then touch sensing is maintained, but threshold voltage increases causing photo-induced current decay
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors illumination conditions and adjusts the bias voltage and switch line voltages accordingly. This feedback loop compensates for threshold voltage changes in real-time, maintaining stable photo-induced current output even during continuous illumination and ensuring reliable touch sensing
Solution Approach 2:
The patent makes the electrical parameters dynamic by continuously adjusting voltage levels based on illumination conditions. The bias voltage and switch line voltages are not fixed but adapt to changing environmental light conditions, allowing the photo thin-film transistor to maintain optimal performance during continuous operation without threshold voltage degradation
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
The solution effectively maintains the reliability and sensitivity of the photo element by preventing threshold voltage increase and photo-induced current decay, ensuring accurate touch event determination across different illumination conditions.
Implementation Method 1
The photo element comprises a photo thin-film transistor... capable of sensing the light and thus inducing photo-induced currents
Data Source
AI summary
A photo element includes a photo thin film transistor (TFT), a switch thin film transistor, and a compensation thin film transistor. A bias line provides a bias voltage to the photo TFT. The photo TFT generates a photo-induced current under an illuminated environment. A first switch line provides a voltage to open the switch TFT, and thus the photo-induced current is read out through a readout line. A second switch line provides compensation current to open the compensation TFT. The compensation current applies a reverse-biased stress to the photo TFT; therefore the threshold voltage and sensitivity of the photo TFT can be maintained.