Integrated LCD Touch Sensing via Voltage Boosting
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Solution Overview
Problem
Large-scale liquid crystal displays (LCDs) with touch sensing functionality face reduced touch sensitivity and responsiveness due to increased trace resistance and parasitic capacitance in readout lines, which also hinder the achievement of a thin profile and low cost design.
Innovation Solution
The implementation of a sensing unit comprising a first transistor, a first capacitor, a second capacitor, a voltage boost unit, and a second transistor, which generates an analog readout signal by boosting the primary sense voltage to a secondary sense voltage through capacitive coupling, thereby enhancing touch sensitivity and reducing the impact of trace resistance in readout lines, and integrating these units into the display panel for a thinner design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the touch panel dimensions are increased, then the display area is enlarged, but the trace resistance of the readout lines increases causing reduced touch sensitivity
Solution Approach 1:
The patent merges the touch sensing function with the liquid crystal display by integrating sensing capacitors and readout circuits directly into the display panel structure. This integration allows the touch sensing signals to be read out through the existing display signal lines, thereby reducing the impact of trace resistance on touch sensitivity while maintaining large display area.
2Area of stationary object
If the touch panel dimensions are increased, then the display area is enlarged, but the parasitic capacitance of the readout lines increases causing increased transmission delay
Solution Approach 1:
The patent segments the touch panel into multiple sensing regions with distributed sensing capacitors, each connected to local readout circuits. This segmentation reduces the distance that signals must travel through readout lines, thereby reducing parasitic capacitance effects and transmission delay while maintaining large overall display area.
3Adaptability or versatility
If an external touch panel is attached to the display, then touch sensing functionality is added, but the profile thickness increases
Solution Approach 1:
The patent combines the touch sensing layer with the liquid crystal display layers to form an integrated structure. The sensing capacitors are formed using the same transparent electrodes and conductive layers that are already part of the display structure, eliminating the need for separate external touch panel attachment and maintaining a thin profile.
4Adaptability or versatility
If an external touch panel is attached to the display, then touch sensing functionality is added, but the manufacturing cost increases
Solution Approach 1:
The patent merges the touch sensing function with the liquid crystal display manufacturing process by using the same material layers and fabrication steps. The sensing capacitors are formed during the display manufacturing process itself, eliminating the need for separate touch panel manufacturing and assembly operations, thereby reducing overall manufacturing cost.
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 solution enhances touch sensitivity by enlarging the sense voltage difference during touch events and allows for a thinner, more cost-effective liquid crystal display with improved responsiveness and multitouch functionality.
Implementation Method 1
a voltage boost unit and a second transistor. The voltage boost unit, electrically connected to the scan line and the second capacitor, is put in use for boosting a primary sense voltage at the first end of the second capacitor to become a secondary sense voltage according to the scan signal
Data Source
AI summary
A liquid crystal display having touch sensing functionality includes a display panel and a sensing unit integrated in the display panel. The display panel has a gate line for delivering a gate signal, a scan line for delivering a scan signal and a readout line for delivering a readout signal. The sensing unit resets a sense voltage according to the low-level voltage of the gate signal. Further, the sensing unit performs a pull-up operation on the sense voltage according to the high-level voltage of the gate signal and performs a boost operation on the sense voltage according to the high-level voltage of the scan signal, for enhancing touch sensitivity. The readout signal is generated by the sensing unit according to the sense voltage and the high-level voltage of the gate signal.