Touch-Sensing Reading Device With Signal-Offset Adjustment
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Solution Overview
Problem
Existing self-capacitance touch devices face challenges in accurately sensing touch events due to significant disparities in capacitance values between the self-capacitance touch capacitor and the internal capacitor, leading to difficulties in receiving electrical charge.
Innovation Solution
A touch sensing reading device with an operation circuit and adjustment circuit that utilizes an adjustment signal to offset the voltage values of the sensing and driving signals, allowing the feedback capacitor to receive larger voltage signals without needing a larger capacitance value, thereby enabling accurate sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the self-capacitance touch capacitor has a larger capacitance value to sense touch events, then the sensing capability is improved, but the internal capacitor cannot receive the electrical charge due to substantial disparity in capacitance values
Solution Approach 1:
The patent introduces an adjustment circuit as an intermediary between the self-capacitance touch capacitor and the internal capacitor. This circuit includes a voltage follower and a capacitor that couples the touch electrode to the summing node, enabling the internal capacitor to receive charge from the touch capacitor even when there is a substantial disparity in capacitance values. The adjustment circuit mediates the charge transfer process, ensuring reliable sensing without requiring the internal capacitor to directly handle large capacitance differences.
2Reliability
If the internal capacitor increases its capacitance value to receive charge from the self-capacitance touch capacitor, then the charge reception capability is improved, but the circuit area increases
Solution Approach 1:
The adjustment circuit serves as a mediator that enables the internal capacitor to receive charge from the touch capacitor without requiring the internal capacitor to increase its capacitance value. The voltage follower and coupling capacitor in the adjustment circuit handle the charge transfer, allowing the internal capacitor to maintain its original small size while still effectively receiving charge from the larger touch capacitor.
Solution Approach 2:
The patent replaces the traditional direct charge transfer mechanism with an adjusted charge transfer path using the adjustment circuit. Instead of relying on direct capacitive coupling that would require large capacitor values, the system uses a voltage follower and coupling capacitor to mediate the charge transfer, substituting the mechanical/direct electrical connection with a controlled signal processing approach that saves circuit area.
3Adaptability or versatility
If the feedback capacitor receives larger voltage signals, then the sensing range is improved, but the feedback capacitor needs a larger capacitance value which increases circuit area
Solution Approach 1:
The adjustment circuit acts as an intermediary that conditions the signal before it reaches the feedback capacitor. The voltage follower and coupling capacitor in the adjustment circuit handle the voltage signal conditioning, allowing the feedback capacitor to receive appropriately scaled signals without requiring a larger capacitance value. This mediates between the need for large sensing voltage range and the constraint of maintaining small capacitor sizes.
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
Enables accurate sensing of touch events with larger voltage signals while reducing the need for larger feedback capacitors, thus saving circuit area.
Implementation Method 1
the capacitive sensing method utilizes charge transfer, whereby the entirety of the electrical charge generated by the self-capacitance touch capacitor during a touch event is transferred to the internal capacitor
Implementation Method 2
utilizes an adjustment signal to offset the voltage values of the sensing and driving signals, reducing the voltage value of the output signal
Data Source
AI summary
A touch sensing reading device includes an operation circuit and an adjustment circuit. The operation circuit includes a feedback capacitor, receives a sensing signal through a first input terminal, receives a driving signal through a second input terminal, and feedbacks an output signal via an output terminal through the feedback capacitor and the first input terminal. The adjustment circuit provides an adjustment signal to the first input terminal of the operation circuit, and adjusts the output signal. A first sub-signal in the adjustment signal is set based on the inverted signal of the driving signal. A second sub-signal in the adjustment signal is set based on the inverted signal of the sensing signal.