Mutual Capacitive Touch Panel Frequency Hopping Circuit
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Solution Overview
Problem
Existing mutual capacitive touch panels face complexity and cost issues due to the need for sequential driving signal input to multiple lines, leading to time delays and complicated control, which affects response uniformity when a large number of driving lines are used.
Innovation Solution
Implementing a mutual capacitive touch panel design where all driving lines are synchronously driven with different frequencies, using a signal output unit to simultaneously output driving signals and a signal separation unit to amplify and separate sensing signals, thereby simplifying circuitry and improving response uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If driving signals with a specific frequency are inputted one by one to each driving line sequentially, then the mutual capacitance can be detected, but the circuitry becomes very complicated and costly, and time delays occur affecting response uniformity
Solution Approach 1:
The patent divides the detection process into two independent stages: first, all driving lines are driven simultaneously with different frequencies; second, the sensing signals are separated by frequency to identify which driving line experienced capacitance changes. This segmentation allows parallel processing while maintaining detection accuracy.
Solution Approach 2:
The patent changes the frequency parameter of driving signals to enable simultaneous driving of multiple lines. Each driving line receives a driving signal with a unique frequency, allowing the system to distinguish signals from different lines through frequency separation after sensing.
2Measurement precision
If driving signals with a specific frequency are inputted one by one to each driving line sequentially, then the mutual capacitance can be detected, but the control becomes complicated and time delays occur affecting response uniformity
Solution Approach 1:
The patent segments the detection task into simultaneous driving phase and sequential analysis phase. During the driving phase, all lines operate in parallel without time delays. The time-consuming separation and analysis occur after signal collection, eliminating delays from the critical detection path.
Solution Approach 2:
The patent maintains continuous simultaneous driving of all driving lines during the sensing period, ensuring that no time is lost to sequential switching. This continuous parallel operation eliminates the time delays inherent in sequential driving methods.
3Measurement precision
If driving signals with a specific frequency are inputted one by one to each driving line sequentially, then the mutual capacitance can be detected, but the cost increases due to complicated circuitry
Solution Approach 1:
The patent merges the driving functions for all driving lines into a single simultaneous operation, and combines the sensing functions into shared preamplifiers. This reduces the number of independent signal paths and associated circuit components, lowering manufacturing cost while maintaining detection capability.
Solution Approach 2:
The patent designs preamplifiers and signal processing circuits that can handle multiple frequency signals simultaneously, making these components multi-functional. This universality reduces the need for dedicated circuits for each driving line, simplifying the overall system and reducing cost.
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 reduces circuit complexity and cost while enhancing the uniformity of output signals by allowing simultaneous input of driving signals with different frequencies, reducing time delays and improving control ease, especially in large touch panels.
Implementation Method 1
a preamplifier configured to capture sensing signals from the sensing lines, and amplify the sensing signals
Implementation Method 2
a mutual capacitance Cm that is formed by a spatial fringe electric field generated between the non-overlapped portions of electrodes of the driving lines and the sensing lines
Implementation Method 3
parasitic capacitances are formed between the finger and the driving lines and between the finger and the sensing lines. A portion of the signals will be directly leaked to the ground through the user's body or the grounded object via the parasitic capacitance
Data Source
AI summary
The present invention provides a mutual capacitive touch panel, including: a plurality of driving lines; a plurality of sensing lines intersecting with the plurality of driving lines; a signal output unit disposed at input ends of the driving lines is configured to simultaneously output driving signals with different frequencies to all the driving lines; a preamplifier disposed at output ends of the sensing lines is configured to capture sensing signals from the sensing lines, and amplify the sensing signals and then output the amplified sensing signals to a signal separation unit; the signal separation unit connected to the preamplifier is configured to separate the sensing signals with different frequencies and obtain addresses of the driving lines corresponding to the sensing signals. The signal output unit determines the frequency sequence of the driving signals every the first predetermined time interval based on the hopping rule, and changes the frequency of the driving signal of each of the columns of the driving lines based on the determined frequency sequence.