Capacitive Level Sensing Circuit for Proportional Fluid Detection
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Solution Overview
Problem
Existing touch-sensitive technologies are limited by proprietary hardware/software dependencies, lack of proportional responses, increased costs due to multiple sensing pads and microcontroller inputs, inability to distinguish between material types, and location restrictions, particularly in fluid level detection applications.
Innovation Solution
A level sensing circuit board with sensing plates and a variable frequency oscillator, where the ground plane surrounds the sensing plates to nullify responses and detect materials based on electrical conductivity, distance, and surface area, using a microcontroller with memory and computer program code to provide proportional responses and distinguish between materials, including non-conductive ones, and control devices like pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensing pads and microcontroller inputs are used to perform level detection, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a single sensing pad that can detect multiple fluid levels through analog output signals, eliminating the need for multiple discrete sensing pads. The microcontroller processes analog signals to determine multiple level thresholds, making one pad serve multiple detection functions simultaneously.
Solution Approach 2:
The invention utilizes analog output signals with varying voltage levels corresponding to different fluid levels. By measuring the continuous analog voltage rather than discrete binary states, the system can distinguish multiple levels from a single sensing pad, effectively changing the detection parameter from binary to continuous.
2Reliability
If proprietary hardware and software are used for touch-sensitive technology, then reliability is improved, but adaptability and ease of manufacture worsen
Solution Approach 1:
The patent employs a microcontroller with downloadable software that can be adapted to different applications and requirements. This universal platform allows the same hardware to serve multiple purposes - fluid level detection, material identification, conductivity measurement - without requiring proprietary application-specific hardware for each function.
Solution Approach 2:
The invention uses software libraries that can be copied and downloaded into microcontrollers, allowing the detection logic and processing algorithms to be replicated across different hardware platforms. This software-based approach provides reliability through consistent algorithm execution while maintaining adaptability through software customization.
3Device complexity
If conventional sensing pads with binary output states are used, then device complexity is reduced, but measurement precision and ability to distinguish material types worsen
Solution Approach 1:
The patent changes the output parameter from binary (activated/not activated) to continuous analog voltage levels. The sensing pad produces different analog voltages corresponding to different fluid levels, material types, and conductivity values, enabling precise measurement while maintaining relatively simple hardware architecture.
Solution Approach 2:
The invention replaces the mechanical/electrical binary switch concept with an analog electrical signal system. Instead of discrete on/off states, the sensing pad generates continuous voltage variations that encode multiple pieces of information (level, material type, conductivity) simultaneously, substituting simple binary electronics with richer analog signal processing.
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 cost-effective, flexible, and location-independent fluid level detection with proportional responses, allowing differentiation between materials and fluid types, reducing hardware requirements and enabling control of devices based on sensed fluid levels.
Implementation Method 1
a sensing capacitor having a sensing plate serving as a positive plate for detecting material placed in front of it
Implementation Method 2
detect materials based on electrical conductivity, distance, and surface area
Data Source
Figure 1a~1b
Figure 2~3c
Figure 4~5
AI summary
A level sensing circuit board featuring at least one processor and at least one memory including computer program code, where the at least one memory and computer program code are configured, with the at least one processor, to cause the apparatus at least to: respond to a signal containing information related to the electrical conductivity of a material causing a stimulus to a sensing plate that corresponds to a positive plate of a capacitor directly connected to an input of a comparator that forms part of a variable frequency oscillator; and determine a proportional response containing information about the material causing the stimulus to the sensing plate based at least partly on the signal received. The level sensing circuit may be used as a means to turn a pump on or off based on a sensed fluid level.