Capacitance Detection Circuit Environmental Compensation
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Solution Overview
Problem
Electrostatic capacitance detection circuits in touch-type input devices are affected by environmental variations such as temperature and humidity, leading to inaccurate touch detection and sensitivity issues.
Innovation Solution
A capacitance detection circuit that includes a sense pin, an analog front-end circuit with variable input-output characteristics, an analog-to-digital converter, and a controller to adjust the circuit's response based on environmental changes, using a temperature sensor and compensation capacitors to maintain consistent detection across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor electrode film is used for capacitance detection, then touch detection sensitivity is improved, but detection accuracy deteriorates due to environmental variations such as temperature and humidity
Solution Approach 1:
The patent changes the input-output characteristic parameters of the analog front-end circuit based on environmental conditions. Specifically, the conversion gain and offset voltage are adjusted according to temperature and humidity levels to compensate for the environmental effects on the sensor electrode capacitance, thereby maintaining detection accuracy while preserving sensitivity
Solution Approach 2:
The patent implements a feedback mechanism where the actual environmental conditions (temperature and humidity) are measured and used to adjust the analog front-end circuit characteristics. This closed-loop control ensures that the detection system continuously adapts to environmental changes, resolving the contradiction between maintaining sensitivity and ensuring accuracy
2Device complexity
If the analog front-end circuit operates with fixed input-output characteristics, then circuit simplicity is maintained, but detection accuracy deteriorates under varying environmental conditions
Solution Approach 1:
The patent transforms the static analog front-end circuit into a dynamic one by enabling real-time adjustment of its input-output characteristics. The circuit can switch between different conversion gains and offset voltages based on environmental conditions, providing adaptability without requiring a completely complex redesign of the overall system
Solution Approach 2:
The analog front-end circuit is designed to perform multiple functions: it can operate with different conversion gains and offset voltages to accommodate various environmental conditions. This multi-functionality allows a single circuit design to handle both simple and complex detection scenarios, reducing the need for multiple specialized circuits
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 effectively reduces the influence of temperature and humidity on electrostatic capacitance detection, enhancing the accuracy and sensitivity of touch detection in touch-type input devices.
Implementation Method 1
a plurality of sensor electrodes convert variation of electrostatic capacitances (referred to as a capacitance below) generated by a user input to electrical signals
Implementation Method 2
using a temperature sensor and compensation capacitors to maintain consistent detection across varying conditions
Data Source
AI summary
A capacitance detection circuit that is capable of reducing the influence of an environmental variation such as temperature. The capacitance detection circuit detects an electrostatic capacitance of a sensor electrode. A sense pin is connected to the sensor electrode. An analog front end circuit converts the electrostatic capacitance of the sensor electrode to an electrical signal, wherein an input-output characteristic of the analog front end circuit is variable. A controller adjusts the input-output characteristic of the analog front end circuit according to the environmental variation.