Multi-Frequency Touch Panel Blind Zone Elimination
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Solution Overview
Problem
Mutual capacitive touch panels suffer from a blind zone in detection, where changes in capacitance are undetectable, leading to incomplete touch signal detection due to capacitance values being close to background noise.
Innovation Solution
Implementing a touch panel with multiple signal detecting units, each comprising a signal inputting unit, a preamplifier, and a signal separating unit with band-pass filters, which input and separate signals at multiple frequencies, effectively reducing or eliminating the blind zone by enhancing detection sensitivity and range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single driving signal frequency is used in mutual capacitive touch panel, then the device complexity is reduced, but a blind zone appears where capacitance changes are undetectable
Solution Approach 1:
The patent applies dynamics by making the driving signal frequency variable rather than fixed. Multiple driving signal frequencies are sequentially applied to the touch panel, allowing the system to dynamically switch between different frequency bands. This enables detection across multiple capacitance response curves (F1, F2, F3), eliminating the blind zone that exists when using a single fixed frequency while maintaining manageable device complexity through systematic frequency switching.
2Reliability
If multiple driving signal frequencies are applied, then the detectable region is enlarged and blind zone is reduced, but the device complexity increases
Solution Approach 1:
The patent implements periodic action by sequentially applying driving signals at different frequencies in a systematic cycle. The signal detecting unit operates in periodic phases: first applying a driving signal at frequency f1 and detecting response, then switching to frequency f2, and continuing this pattern. This periodic multi-frequency approach enlarges the detectable region by covering different capacitance response characteristics while managing complexity through structured, repeating detection cycles rather than requiring simultaneous complex multi-frequency processing.
Solution Approach 2:
The patent applies segmentation by dividing the detection process into separate frequency-based stages. Instead of attempting to process all frequencies simultaneously, the system segments the detection into discrete frequency steps (f1, f2, f3, etc.), where each frequency targets specific detection zones. This segmentation of the detection process into manageable frequency segments reduces the overall complexity while achieving comprehensive coverage through the combination of segmented results.
3Measurement precision
If multiple signal detecting units are used to cover different frequencies, then detection sensitivity is improved, but manufacturing complexity and costs increase
Solution Approach 1:
The patent applies universality by designing a single signal detecting unit that performs multiple functions across different frequency bands. Rather than manufacturing separate detecting units for each frequency, the same hardware unit is configured to sequentially operate at multiple frequencies (f1, f2, f3). This multi-functional approach maintains high detection sensitivity by covering multiple capacitance response curves while significantly reducing manufacturing complexity and costs compared to producing multiple specialized detecting units.
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 significantly enlarges the detectable region, improves detection sensitivity, and allows for a wider detection range, reducing manufacturing complexity and costs by enabling a single driver chip to be used across various touch panels.
Implementation Method 1
a signal separating unit, which includes n band-pass filters, is configured to separate the signals respectively having n frequencies
Implementation Method 2
a preamplifier, which is connected to a signal output end of the touch panel, is configured to acquire the output signals outputted from the touch panel, and amplify and output the signals
Data Source
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AI summary
The present invention provides a touch panel, which includes a plurality of signal input ends and a plurality of signal output ends, where the touch panel further includes at least one signal detecting unit which includes: a signal inputting unit (M), a preamplifier (A1, A2), and a signal separating unit; where the signal inputting unit, which is connected to a signal input end of the touch panel, is configured to input driving signals respectively having n frequencies, where n is an integer not less than 2; the preamplifier (A1, A2), which is connected to a signal output end of the touch panel, is configured to acquire the output signals outputted from the touch panel, and amplify and output the signals to the signal separating unit; the signal separating unit, which includes n band-pass filters (nl, n2, n3), is configured to separate the signals respectively having n frequencies. In the touch panel according to the present invention which is driven by signals respectively having n frequencies, the blind zone of the touch panel can be decreased or even eliminated, thus enlarging the detectable region and greatly improving the detection sensitivity of the touch panel.