Capacitive Touch Sensor Testing via Resistor-Based Current Simulation
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Solution Overview
Problem
The challenge lies in testing capacitive touch sensors, where precise variable capacitors are difficult to fabricate due to process variations during semiconductor fabrication, making it hard to achieve accurate detection of tiny capacitance variations.
Innovation Solution
A test system that uses a resistor and a signal generator to simulate current variations, eliminating the need for a physical capacitor, with a micro controller generating control information based on a test table to determine the capacitive touch sensor's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a precise variable capacitor is used for testing, then testing accuracy is improved, but manufacturing difficulty increases due to process variations
Solution Approach 1:
The patent uses a resistor to simulate the electrical characteristics of a capacitor during testing. Instead of fabricating precise physical capacitors, the system creates an electrical equivalent using a resistor with known values, which can be easily manufactured and provides consistent test results without suffering from capacitor fabrication process variations
Solution Approach 2:
The patent changes the testing approach from using actual capacitors with varying physical parameters to using a resistor where the electrical parameter (resistance) can be precisely controlled and changed through digital values stored in a test table, enabling accurate simulation of different capacitor values without physical fabrication variations
2Measurement precision
If a variable capacitor with fine-tunable capacitance is used, then detection precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the complex variable capacitor device with a simple resistor and a digital test table. The resistor serves as a static component while the dynamic capacitance values are simulated through pre-calculated resistance values stored in memory, eliminating the need for complex variable capacitor mechanisms
Solution Approach 2:
The patent substitutes the mechanical/electrical variable capacitor system with a digital control system. Instead of physically adjusting capacitor values through mechanical switches or variable components, the system uses digital values in a test table to control a resistor, replacing complex electrical adjustment mechanisms with simple digital storage and retrieval
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 testing costs and increases accuracy by simulating different capacitors without the need for a precise variable capacitor, allowing for effective testing of capacitive touch sensors.
Implementation Method 1
the signal generator provides a test voltage to a second end of the resistor according to control information. In this way, the resistor generates a test current according to the test voltage
Data Source
AI summary
A test system for testing a capacitive touch sensor is provided. The test system includes a resistor, a signal generator and a micro controller. A first end of the resistor is electrically connected to a sensing port of the capacitive touch sensor. The signal generator provides a test voltage to a second end of the resistor according to control information. In this way, the resistor generates a test current according to the test voltage, and the capacitive touch sensor provides a voltage difference to the sensing port according to a plurality of switching signals, and converts the test current into test information. The micro controller generates the control information according to a test table, and compares the test information according to the test table, so as to determine whether an operation of the capacitive touch sensor is normal.