Multi-Frequency Touch Sensing Circuit for Higher SNR Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display devices face challenges in effectively separating and removing noise from sensing signals while determining touch or approach inputs, leading to reduced signal-to-noise ratio (SNR) and impaired accuracy.
Innovation Solution
The input sensing device employs first and second driving electrodes operating at different frequencies, with analog front-end circuits to separate and filter sensing signals of these frequencies, and a sensing driver that generates digital sensing data by recombining these signals, utilizing charge amplification, filtering, and differential amplification to enhance SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing signals are processed without frequency separation, then processing speed is maintained, but noise removal effectiveness deteriorates leading to reduced SNR
Solution Approach 1:
The sensing driver divides the sensing signal processing into separate frequency channels using first and second band-pass filters. Each filter processes signals at its designated frequency (first frequency for first driving electrodes, second frequency for second driving electrodes), separating the signal processing path to improve noise removal effectiveness while maintaining manageable circuit complexity through systematic organization.
Solution Approach 2:
The patent applies frequency domain parameter changes by using band-pass filters with specific frequency characteristics matched to the driving electrode frequencies. The filters are designed with center frequencies corresponding to the driving signals, allowing selective passage of desired frequency components while attenuating noise at other frequencies, thereby improving SNR through parameter optimization.
2Measurement precision
If multiple driving electrodes operate at different frequencies, then noise removal effectiveness is improved, but signal processing complexity increases
Solution Approach 1:
The analog front-end circuits are segmented into dedicated processing paths for each driving electrode frequency. First band-pass filter circuits process signals from first driving electrodes at the first frequency, while second band-pass filter circuits process signals from second driving electrodes at the second frequency. This segmentation allows complex multi-frequency processing to be broken down into manageable, independent frequency channels.
Solution Approach 2:
The sensing driver is designed with universal processing capability that handles multiple frequency channels through identical circuit topologies. The same filter-amplifier-converter architecture is replicated for different frequencies, allowing the system to process multiple driving electrode frequencies using a unified design approach, thereby managing complexity through design reuse.
3Measurement precision
If band-pass filters are used for each frequency, then noise filtering capability is improved, but circuit area increases
Solution Approach 1:
The band-pass filters are designed with optimized frequency parameters where the center frequency of each filter matches the operating frequency of its corresponding driving electrode. This parameter matching ensures maximum signal transmission at the desired frequency while providing effective noise rejection at other frequencies, achieving superior filtering effectiveness with efficient use of circuit resources.
Solution Approach 2:
The filtering system applies partial frequency processing by focusing band-pass filters on specific frequency bands corresponding to each driving electrode. Rather than attempting to process all frequencies simultaneously with a single complex filter, the system applies targeted filtering at each frequency band, achieving effective noise removal with reduced overall circuit complexity and area.
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 improves the SNR of sensing signals, enabling high-speed and accurate detection of touch or approach inputs by effectively separating and filtering noise, thereby enhancing the overall performance of the display device.
Implementation Method 1
a charge amplification component that differentially amplifies a first sensing signal and a second sensing signal
Implementation Method 2
a filter component that filters the first differential signal and outputs a first filtered signal and a second filtered signal in different frequency bands
Implementation Method 3
a buffer component that outputs a first combined differential signal and a second combined differential signal based on the first to fourth filtered signals
Data Source
AI summary
An input sensing device includes first driving electrodes, second driving electrodes, and sensing electrodes, and a sensing driver that transmits a first driving signal to the first driving electrodes at a first frequency, transmits a second driving signal to the second driving electrodes at a second frequency, and determines a touch or approach of an external object based on sensing signals received from the sensing electrodes. The sensing driver includes analog front-end circuits that separate a sensing signal of the first frequency and a sensing signal of the second frequency that are received from the respective sensing electrodes, and generate digital sensing data based on a result of a recombination of the separated sensing signals.