Liquid Crystal Device Resetting Storage Capacitors for Accurate Image Sensing
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Solution Overview
Problem
Liquid crystal display devices with image sensor arrays face image distortion when switching from display mode to scan mode due to parasitic voltages stored in storage capacitors, which are not completely reset, leading to inaccurate scanned images.
Innovation Solution
The liquid crystal device employs a method where a high level voltage is simultaneously applied to multiple gate lines during the transition to scan mode, and a reset voltage is applied to thin film transistors connected to these gate lines, ensuring complete charging of storage capacitors with a reset voltage before image sensing begins, thereby eliminating parasitic voltages and preventing image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the liquid crystal device switches from display mode to scan mode, then image sensing function is activated, but parasitic voltages in storage capacitors cause image distortion
Solution Approach 1:
A reset voltage is applied to the storage capacitors before image sensing begins in scan mode, preemptively clearing parasitic voltages that would otherwise cause image distortion. This preliminary reset action ensures accurate image capture when switching from display to scan mode.
2Reliability
If a reset voltage is applied to storage capacitors during mode transition, then parasitic voltages are eliminated, but additional control complexity is introduced
Solution Approach 1:
The reset voltage application is merged with the existing mode transition control sequence. The driving circuit utilizes the same control infrastructure for both display and scan modes, integrating the reset function into the mode switching process rather than adding a separate independent control system.
3Manufacturing precision
If multiple gate lines receive high level voltage simultaneously, then storage capacitors are fully charged with reset voltage, but power consumption increases
Solution Approach 1:
The high level voltage is applied to multiple gate lines simultaneously only during the brief mode transition period when reset is required, then returns to normal sequential operation. This periodic simultaneous activation ensures complete capacitor charging without sustaining high power consumption during image sensing operation.
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
This approach allows for accurate image sensing by ensuring that storage capacitors are fully charged with a reset voltage before image scanning, preventing distortion and ensuring reliable image capture when switching from display to scan mode.
Implementation Method 1
a sensing part generating a photo voltage corresponding to an incident light and storing the photo voltage
Implementation Method 2
a liquid crystal capacitor connected to the thin film transistor is formed in each pixel region. The liquid crystal capacitor is turned on/off by the thin film transistor, thereby modulating transmittance of incident light
Data Source
AI summary
A liquid crystal device and method for displaying and sensing images are provided. According to one embodiment, the liquid crystal device includes a sensing part to sense an image in a scan mode of the liquid crystal device, the sensing part including at least one charging element which is charged at a start of the scan mode with a reset voltage, so as to reset the at least one charging element for the scan mode; and a display part to display an image corresponding to a data signal according to a scan signal in a display mode of the liquid crystal device.