TFT Touch Display Back-Channel Current Sensing
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Solution Overview
Problem
Existing touch panels, particularly those using thin film transistors (TFTs), face challenges with weight, transmittance, and aperture rate due to the combination of TFT LCD and touch sensor layers, and suffer from low touch resolution and increased hardware costs.
Innovation Solution
A TFT touch display device with a network of control and sensor lines intersecting at thin film transistors, where each transistor is connected to both lines and a power source, allowing for back-channel current generation and sensing when touched, enabling accurate touch location detection without additional hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent conductive layer is used as the touch electrode, then transmittance is improved, but touch resolution deteriorates
Solution Approach 1:
The patent combines the touch sensing function with the existing TFT LCD structure by using the TFT channel as the sensing element. The sensor line is integrated into the TFT structure, merging the display and touch sensing functions into a single device, thereby achieving high transmittance without compromising touch resolution
Solution Approach 2:
The patent applies different functions to different regions of the TFT structure. The channel region serves dual purposes: display switching and touch sensing. By locally utilizing the channel current changes caused by touch, the system achieves high resolution touch detection while maintaining overall transmittance
2Measurement precision
If an opaque conductive layer is used as the touch electrode, then touch resolution is improved, but aperture rate deteriorates
Solution Approach 1:
The patent merges the touch electrode function with the existing TFT channel structure, eliminating the need for separate opaque conductive layers. The sensor line is integrated into the TFT, allowing touch sensing without blocking light, thus improving aperture rate while maintaining touch resolution
Solution Approach 2:
The patent extracts the touch sensing function from the traditional separate touch electrode layer and integrates it into the TFT structure. This extraction eliminates the need for opaque conductive materials, thereby improving light transmission while preserving touch detection capability
3Measurement precision
If multiple sheets of glass are combined for TFT LCD and touch sensor, then sensing accuracy is improved, but weight deteriorates
Solution Approach 1:
The patent combines the touch sensing function with the existing TFT LCD structure by using the TFT channel as the sensing element. The sensor line is integrated into the TFT structure, merging the display and touch sensing functions into a single device, thereby achieving high transmittance without compromising touch resolution
Solution Approach 2:
The TFT structure serves multiple functions: display switching and touch sensing. The channel region is utilized for both driving the liquid crystal and detecting touch input, eliminating the need for separate touch sensor glass sheets and reducing overall device weight
4Ease of manufacture
If traditional touch sensor structure is used, then manufacturing simplicity is maintained, but device complexity deteriorates
Solution Approach 1:
The patent combines the touch sensing function with the existing TFT LCD structure by using the TFT channel as the sensing element. The sensor line is integrated into the TFT structure, merging the display and touch sensing functions into a single device, thereby achieving high transmittance without compromising touch resolution
Solution Approach 2:
The TFT channel serves itself for dual purposes: display operation and touch sensing. The same TFT structure that drives the liquid crystal also detects touch input through channel current changes, eliminating the need for additional dedicated sensing components and simplifying manufacturing
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 accuracy and resolution while maintaining a lightweight design, addressing the limitations of prior art by utilizing existing TFTs on LCD panels for touch sensing without increasing hardware costs.
Implementation Method 1
each TFT is connected to the control line, the sensor line, and a power source, such that the TFT is turned on to generate a back-channel current when there is an object approaching to the TFT
Data Source
AI summary
A TFT touch display device includes a plurality of mutually vertical control lines and sensor lines and a plurality of TFTs. Each TFT is disposed at an intersection of one of the plurality of control line and one of the plurality of sensor line. The TFT is connected to a corresponding control line, a corresponding sensor line, and a power source. When there is an object approaching to the TFT, the TFT is turned on and a back-channel current is generated. A control unit is connected to the plurality of control lines to respectively provide a control signal to the plurality of control lines. A current sensing unit is connected to the plurality of sensor lines to respectively sense a current generated by the TFTs.