Touchpad Oscillator Circuit With Asymmetric Capacitors for Low-Power Sensing
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Solution Overview
Problem
Existing keyless systems with capacitive touch sensors face challenges in balancing sensitivity and current consumption, as higher oscillator frequencies increase sensitivity but also consume more power, while lower frequencies reduce sensitivity.
Innovation Solution
The proposed oscillator device incorporates a differential oscillating structure with a first capacitor connected to a touchpad and a second capacitor, where the total capacitance of the first capacitor is lower than the second, and an output circuit to control the oscillation signal, enabling selective output based on an enable signal, thereby improving sensitivity and reducing current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the oscillator output frequency is increased to improve sensitivity, then the sensitivity of the touch sensor is improved, but the current consumption increases
Solution Approach 1:
The patent applies asymmetry by using different capacitance values for the first capacitor (connected to touchpad) and the second capacitor (connected to ground). Specifically, the first capacitor has a smaller capacitance value than the second capacitor, creating an asymmetric capacitive divider configuration that optimizes the oscillation frequency and sensitivity while controlling current consumption.
Solution Approach 2:
The patent changes the capacitance parameters of the capacitors in the oscillation circuit. By selecting specific capacitance values where C1 < C2 (with C1 being the first capacitor and C2 being the second capacitor), the system achieves optimal sensitivity and frequency characteristics without excessive current consumption.
2Use of energy by moving object
If the oscillator output frequency is decreased to reduce current consumption, then the current consumption is reduced, but the sensitivity of the touch sensor decreases
Solution Approach 1:
The asymmetric capacitive configuration with C1 < C2 ensures that the oscillation frequency and sensitivity are optimized for the given operating conditions, achieving a balance between low current consumption and adequate sensitivity without requiring frequency reduction.
Solution Approach 2:
By optimizing the capacitance ratio between C1 and C2, the system achieves the desired sensitivity at lower frequencies, eliminating the need to trade off sensitivity for reduced current consumption.
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 configuration enhances sensitivity while reducing current consumption, achieving stable and efficient touch sensing operations with lower frequencies, outperforming typical systems by approximately 44% in sensitivity at the same output frequency.
Implementation Method 1
a first capacitor connected between the first terminal and a ground, and a second capacitor connected between the second terminal and the ground, where a total capacitance of the first capacitor is different from a total capacitance of the second capacitor
Data Source
AI summary
An oscillator device includes a touchpad, and an oscillator that includes an oscillation core having a second terminal configured to output an oscillation signal generated by the oscillation core based on an input to a first terminal of the oscillation core, a first capacitor connected between the first terminal and a ground, and a second capacitor connected between the second terminal and the ground, where the first capacitor is connected to the touchpad, and where a total capacitance of the first capacitor is different from a total capacitance of the second capacitor.