Touch Signal Scan Apparatus Frequency Multiplexing
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Solution Overview
Problem
Capacitive touch screens face challenges in accurately detecting moving fingers due to variable signal amplitudes and profiles caused by changing angles and speeds, leading to low precision and inefficient scanning, especially when multiple touch points are involved.
Innovation Solution
A touch signal scan apparatus and method that supplies drive signals with two different frequencies to adjacent drive lines, which are swapped in subsequent frames, and uses a bandwidth filter to separate sense signals, enabling concurrent driving of multiple lines and improving detection precision and comprehensive information acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If drive signals are injected to each row sequentially in the vertical direction (line by line scanning), then the touch screen can be scanned systematically, but the precision of detecting the touching finger in motion is low and the acquired information is not comprehensive
Solution Approach 1:
The patent segments the drive lines into multiple groups and assigns different drive frequencies to each group. This allows simultaneous scanning of multiple rows with different frequencies, enabling the system to capture moving finger information from multiple angles and positions concurrently, thereby improving both detection precision and scanning efficiency
Solution Approach 2:
The patent employs periodic switching of drive frequencies across different row groups in a time-division multiplexing manner. During different time periods, different groups of rows are activated with specific frequencies, allowing the system to systematically collect comprehensive touch information while maintaining high scanning speed
2Productivity
If the scan speed is increased to follow fast-moving fingers, then the scanning efficiency improves, but the amplitude and profile of the gained touch signal vary with the angle between scan direction and finger movement vector
Solution Approach 1:
The patent applies different drive frequencies to different spatial groups of rows based on their local scanning requirements. By assigning specific frequencies to specific row groups, the system can optimize signal characteristics for each local region, compensating for variations caused by finger movement direction and maintaining signal uniformity across the entire screen
Solution Approach 2:
The patent changes the drive frequency parameter across different row groups and time periods. This parameter variation allows the system to adapt to different scanning scenarios and finger movement patterns, ensuring consistent signal quality regardless of scan speed or finger trajectory
3Adaptability or versatility
If multiple touch points are detected simultaneously, then the touch screen functionality is enhanced, but the output signals of different touch points may be different due to their relative distances and speeds to the spatial location of drive signal
Solution Approach 1:
The patent segments the touch detection into multiple frequency-channels, each corresponding to different row groups. This segmentation allows the system to independently analyze signals from different spatial regions and touch points, accurately distinguishing multiple simultaneous touches even when they have different distances and speeds relative to the drive signal location
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 enhances the precision of detecting moving fingers and improves scanning efficiency by stabilizing signals and reducing scanning time, allowing for accurate detection of multiple touch points and reducing delays caused by resistances and capacitances.
Implementation Method 1
mutual inductive capacitances are formed between the drive lines and the sense lines, where the capacitances at the locations where the drive lines and the sense lines overlap are not changeable by an outside touching object, and the mutual inductive capacitances formed by a fringe electric field generated at the locations where no electrodes overlap are influenced directly by an outside touching object
Implementation Method 2
a bandwidth filter electrically connected with the N amplifiers and configured to separate sense signals output from the N amplifiers so as to obtain the sense signals corresponding to the respective drive signals with the two different frequencies
Data Source
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AI summary
A touch signal scan apparatus and a touch signal scan method are disclosed. The apparatus includes: a drive signal supply unit electrically connected with M drive lines in one-to-one correspondence, an electrode layer in which the M drive lines and N sense lines are arranged, and N amplifiers electrically connected with different output ends of the N sense lines in one-to-one correspondence. The drive signal supply unit is configured to supply drive signals with at least two different frequencies to the M drive lines in a period of one frame, and the frequencies of the drive signals supplied to two adjacent drive lines are different. The apparatus further includes a bandwidth filter electrically connected with the N amplifiers and configured to separate sense signals output from the N amplifiers so as to obtain the sense signals corresponding to the respective drive signals with the at least two different frequencies.