Touch Sensor IC Circuit Using One Capacitor for Multiple Electrodes
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Solution Overview
Problem
Conventional touch sensors require a large number of external components, leading to increased size, cost, and power consumption, and are prone to malfunction due to component variability, with noise interference affecting accuracy in determining touch electrode contact by a human body.
Innovation Solution
A semiconductor device with a switch circuit and charging/discharging circuit that connects a touch electrode to a reference voltage node, using a single capacitor for multiple electrodes, and a sensing circuit to compare voltage with a threshold, reducing noise influence and determining touch contact accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional touch sensors use two capacitors and a resistor element for each touch electrode, then the touch sensor can determine touch contact, but the number of externally-mounted components increases, leading to increased size, cost, and power consumption
Solution Approach 1:
The patent merges multiple functions into a single capacitor. The same capacitor is used for both charging the touch electrode and measuring its voltage to determine touch contact. This eliminates the need for separate capacitors and resistor elements for each touch electrode, reducing the number of externally-mounted components while maintaining touch detection functionality
Solution Approach 2:
The patent makes the capacitor universal by using it for multiple purposes: charging the touch electrode, storing charge during measurement, and enabling voltage comparison for touch detection. This multi-functional use of a single capacitor reduces component count and simplifies the circuit configuration
2Reliability
If conventional touch sensors use multiple externally-mounted components, then touch detection is possible, but the influence of difference between components increases, making malfunction more likely
Solution Approach 1:
By combining the functions of multiple capacitors and resistor elements into a single capacitor, the patent reduces component variability and eliminates potential failure points associated with multiple discrete components. The single capacitor approach minimizes the influence of component differences and reduces the likelihood of malfunction
3Ease of manufacture
If conventional touch sensors require multiple external terminals for connecting components, then the circuit can be assembled, but the number of external terminals increases, complicating connections
Solution Approach 1:
The patent reduces the number of external terminals by merging component functions. Instead of requiring separate terminals for multiple capacitors and resistor elements, the simplified circuit configuration requires fewer external terminals, easing the connection process and reducing assembly complexity
4Reliability
If a microcomputer CPU executes software to control the touch sensor IC, then the touch sensor can determine touch contact, but the microcomputer has to bear a heavy load, resulting in increased power consumption
Solution Approach 1:
The patent implements self-service by enabling the touch sensor IC to perform touch detection autonomously through its control circuit. The control circuit directly controls the charging and measuring operations without requiring continuous intervention from the microcomputer CPU, thereby reducing the computational load and power consumption of the microcomputer while maintaining accurate touch contact determination
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 reduces the number of components, decreases power consumption, and enhances accuracy in determining touch electrode contact by minimizing noise interference, thereby improving the efficiency and reliability of touch sensors.
Implementation Method 1
a capacitor; a charging and discharging circuit for performing a charging operation of charging the capacitor, a discharging operation of releasing a charge from the selected touch electrode
Data Source
AI summary
A touch sensor IC includes a switch for connecting, to an external terminal with its voltage to be sensed, a selected one of a plurality of external terminals to which a plurality of touch electrodes is connected. Only one set of two capacitors and a resistor element may therefore be provided for a plurality of touch electrodes. Thus, the number of required components is smaller as compared with a conventional sensor requiring two capacitors and a resistor element for each touch electrode.