Touch Monitoring Circuit Using Acoustic XNOR for Zero-Height Detection
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Solution Overview
Problem
Infrared touch devices face precision errors due to glass protrusions blocking infrared light paths, leading to incorrect detection of touch actions, particularly when a stylus is not in contact with the screen surface.
Innovation Solution
A touch monitoring circuit that utilizes inside and outside sound pick-up circuits to generate sound pick-up signals, which are processed through an XNOR operation to detect screen touches, and further incorporates a whole-machine signal acquisition and zero-touch-height operation to enhance precision by filtering and amplifying these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared light path detection is used for touch sensing, then touch detection capability is achieved, but glass protrusions block the light path causing measurement precision errors
Solution Approach 1:
The patent replaces the optical detection system (infrared light path) with an acoustic detection system (sound wave propagation). Sound waves travel through the glass substrate and are detected by piezoelectric elements, eliminating the blocking effect of glass protrusions that plague optical methods. This substitution of detection physics fundamentally resolves the interference issue.
Solution Approach 2:
The patent introduces sound waves as an intermediary medium to detect touch events. Instead of directly detecting light blockage, the system uses acoustic waves that propagate through the glass and carry information about touch events to piezoelectric sensors, effectively mediating the detection process to avoid direct interference from glass surface irregularities.
2Measurement precision
If sound pick-up circuits are added to detect touch sounds, then touch detection precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the glass substrate serve multiple functions: it acts as both the structural component of the display and the propagation medium for acoustic waves. The piezoelectric elements simultaneously serve as structural support and as acoustic sensors. This multi-functionality reduces the need for separate dedicated touch sensing components, thereby limiting complexity increase.
Solution Approach 2:
The patent merges the touch detection function with the existing display structure. The piezoelectric elements are integrated into the glass substrate or backlight assembly, combining structural support with sensing functionality. This merging approach avoids adding entirely separate sensing systems and reduces overall device complexity.
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 eliminates interference and noise, enabling accurate detection of touch actions on the screen by distinguishing between internal and external sounds, thus improving precision and reducing false detections.
Implementation Method 1
an inside-sound pick-up circuit configured to detect sound inside the touch screen to generate an inside-screen sound pick-up signal; an outside-sound pick-up signal configured to detect sound outside the touch screen to generate an outside-screen sound pick-up signal
Data Source
AI summary
The present application belongs to the technical field of touch detection, providing a touch monitoring circuit, touch display apparatus and electronic device. Sound inside the touch screen is detected by an inside-sound pick-up circuit to generate an inside-screen sound pick-up signal. Sound outside the touch screen is detected by an outside-sound pick-up signal to generate an outside-screen sound pick-up signal. The inside-sound pick-up circuit and the outside-sound pick-up circuit are connected to a signal operation circuit, and the signal operation circuit carries out an XNOR operation on the inside-screen sound pick-up signal and the outside-screen sound pick-up signal, thereby reserving a sound signal transmitted on the touch screen, eliminating a interfering signal inside and outside the touch screen to obtain the screen touch detection signal, and implementing a zero-touch-height detection of the touch screen.