Capacitive Touch Sensor Self-Test for In-Line Production Screening
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Solution Overview
Problem
Current manufacturing processes for capacitive touch sensing devices are inefficient, labor-intensive, and costly due to the need for manual testing, which can result in devices not meeting performance specifications being released to customers.
Innovation Solution
A method for production testing that uses a self-test capacitive circuit to sample and compare values during the manufacturing process, eliminating the need for manual testing and ensuring devices meet specifications by integrating a self-test capacitive circuit within the sensor circuit to simulate a grounded mass and detect defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual testing of each capacitive touch sensing device is performed using a test bench, then device quality and compliance with performance specifications are ensured, but testing becomes time-consuming, labor-intensive, and expensive
Solution Approach 1:
The capacitive touch sensing device performs self-testing by utilizing its own sensor circuit to generate test signals and measure its response. The device applies a test signal to itself through the self-test capacitor and compares the measured capacitance against reference values, enabling automated quality verification without external manual intervention or complex test equipment
Solution Approach 2:
The sensor circuit serves dual functions: it operates as the normal capacitive sensing mechanism during device operation and simultaneously functions as a self-test mechanism during manufacturing. The same sensor circuitry, comparator, and control logic are used for both production testing and operational sensing, eliminating the need for separate dedicated test equipment
2Productivity
If random or spot-testing of manufactured devices is performed, then testing time, labor, and cost are reduced, but devices that do not meet performance specifications may be released to customers
Solution Approach 1:
The self-test function is integrated into the device before it leaves the manufacturing line, allowing quality verification to occur as part of the production process itself. Devices are tested immediately after assembly using their own built-in test capabilities, ensuring that only compliant devices proceed to packaging and distribution
3Reliability
If manual testing methods are used to ensure device compliance, then customer satisfaction is maintained, but manufacturing costs and labor requirements increase significantly
Solution Approach 1:
The manual mechanical testing process using external test benches is replaced with an electronic self-test system integrated into the device. The sensor circuit electronically generates test signals, measures its own response, and automatically determines compliance, eliminating the need for manual operation of complex external testing equipment
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 enables efficient, automated production testing of capacitive touch sensing devices, detecting defects and ensuring compliance with performance requirements, thereby preventing non-compliant devices from being released, while reducing costs and increasing throughput.
Implementation Method 1
a self-test capacitive circuit applying a signal thereto... samples a second value corresponding to the first channel of the capacitive touch sensing device when the capacitive touch sensing device has the self-test capacitive circuit applying a signal thereto
Data Source
AI summary
In one embodiment, a method for production testing of a capacitive touch sensing device is disclosed. In this embodiment, the present technology for production testing of a capacitive touch sensing device samples a first value corresponding to a first channel of a capacitive touch sensing device when the capacitive touch sensing device is in production. The present embodiment also samples a second value corresponding to the first channel of the capacitive touch sensing device when the capacitive touch sensing device has a self-test capacitive circuit applying a signal thereto. The present embodiment compares the first value and the second value to determine a production testing result for the first channel of the capacitive touch sensing device, wherein the sampling of the second value and the comparing the first value and the second value occur during production of the capacitive touch sensing device.