Sensing and control device and method for a weight measurement device
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Solution Overview
Problem
Existing weight measurement devices in cooking appliances face challenges in accurately measuring the weight change of food during cooking due to the need to account for the weight of the cooking vessel and other 'dead' loads, which requires high-precision ADCs, leading to increased costs and complexity.
Innovation Solution
A sensing and control device that uses analog circuitry to subtract the weight of the load unit from the total weight measurement signal, generating a digital signal representing only the weight of the material to be weighted, allowing for precise measurement using a low-cost ADC by converting the pulse width modulated signal into a proportional DC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-precision ADC with larger dynamic range is used to cover the total weight of load unit and food, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent extracts and separately measures the dead load (load unit weight) from the total weight measurement. By measuring the load unit weight independently before food placement and subtracting it from the total weight measurement, the system only needs to resolve the smaller food weight portion with high precision, enabling the use of lower-resolution ADCs while maintaining measurement accuracy.
Solution Approach 2:
The system performs preliminary measurement of the load unit weight before the food is placed on the load unit. This preliminary measurement is stored and used as an offset to be subtracted from subsequent total weight measurements, allowing the ADC to operate in a smaller, more precise range for food weight measurement only.
2Measurement precision
If a high-precision ADC with larger dynamic range is used to cover the total weight of load unit and food, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the dead load component from the total weight measurement and handles it separately through software subtraction. This allows the use of a simpler, lower-resolution ADC that only needs to measure the food weight portion, reducing the complexity requirements for the ADC specification while maintaining overall measurement precision.
3Measurement precision
If the load gauge arrangement is placed closer to the food, then measurement precision is improved, but the sensing accuracy is interfered with by harsh cooking environment
Solution Approach 1:
The patent extracts the dead load measurement from the food weight measurement process. By measuring and storing the load unit weight separately and subtracting it digitally, the system can use a simpler load gauge arrangement that is less susceptible to environmental interference, while still achieving precise food weight measurement through the subtraction method.
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 and precise monitoring of food weight changes during cooking, optimizing the use of integrated MCU components and reducing the need for expensive ADCs, while maintaining accuracy and efficiency in weight measurement.
Implementation Method 1
to transduce the gravity to electrical signal
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The present invention relates to a sensing and control device (40) and method for a weight measurement device (30) comprising a load unit for loading material to be weighted. To enable precise measurement with less expensive components, said sensing and control device comprises analog circuitry (50) configured to receive a weight measurement signal, convert the received weight measurement signal into a first voltage signal, subtract a second voltage signal representing the weight of at least the load unit without being loaded with material to be weighted from the first voltage signal when the load unit is loaded with material to be weighted to generate a third voltage signal representing the weight of the material to be weighted, and control circuitry (60) configured to receive the first voltage signal while the load unit is not loaded with material to be weighted, convert the first voltage signal into a first digital signal, and generate a pulse width modulated, PWM, signal having a pulse width representing the weight measured by the load unit while not being loaded with material to be weighted, and further configured to convert the third voltage signal into a second digital signal representing the weight measurement of the material to be weighted. The analog circuitry (50) is configured to generate the second voltage signal from the PWM signal generated by the control circuitry, wherein the voltage level of the second voltage signal is proportional to the pulse width of the PWM signal.