Ice bin level sensor
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Solution Overview
Problem
Existing ice level sensors in refrigerators face issues such as mechanical failure, false indications due to ice bridging and uneven distribution, and are affected by frost buildup, leading to inaccurate ice level detection and increased manufacturing costs.
Innovation Solution
A projected proximity capacitive sensing system using multiple electrode arrays and a control circuit to detect ice levels by measuring capacitance changes, which dynamically adjusts to environmental conditions and reduces the need for calibration and heaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mechanical bail sensor is used to detect ice level, then the sensor can provide a simple and low-cost detection mechanism, but it suffers from mechanical failure due to wear and tear, damage from food items, and freezing in non-interlock position
Solution Approach 1:
The patent replaces the mechanical bail sensor system with a capacitive sensing system that uses electrical fields instead of mechanical components. The capacitive sensor detects ice level through changes in capacitance caused by the dielectric properties of ice versus air, eliminating mechanical wear, food damage, and freezing issues while maintaining detection functionality.
Solution Approach 2:
The patent introduces a dielectric medium (the capacitive sensor field) as an intermediary between the sensor and the ice. This intermediary allows detection of ice level through electrical field interactions with the ice's dielectric properties, avoiding direct mechanical contact that causes reliability issues.
2Device complexity
If a mechanical bail sensor is used to detect ice level, then the sensor structure is simple, but it provides false full indication when ice bridging occurs because the sensor detects the top layer even though the bin is otherwise empty
Solution Approach 1:
The patent divides the capacitive sensing system into multiple discrete sensing zones along the sensor length. Each zone independently measures capacitance changes, allowing the system to detect ice presence at specific locations rather than providing a single binary reading. This segmentation enables identification of ice bridging conditions where ice may be present at the top but absent in lower regions.
Solution Approach 2:
The patent transitions from a single-point mechanical detection to a distributed multi-zone capacitive sensing approach, adding spatial dimensionality to the measurement. By measuring capacitance across multiple zones simultaneously, the system gains information about ice distribution throughout the bin volume, not just at the top level.
3Reliability
If ultrasonic, optical, or infrared sensors are used to detect ice level, then the sensors provide non-contact detection, but they are affected by fogging and frosting of transmitters, receivers, and light paths
Solution Approach 1:
The patent replaces optical and ultrasonic sensing systems with capacitive sensing that uses electrical fields instead of light or sound waves. Electrical fields are not scattered or absorbed by frost or fog in the same way optical signals are, eliminating the interference problems that plague non-contact optical sensors in cold, humid environments.
Solution Approach 2:
The patent changes the detection parameter from optical or acoustic properties to electrical capacitance properties. By measuring capacitance changes caused by the dielectric properties of ice, the system avoids the problems of light scattering by frost while still achieving non-contact detection functionality.
4Measurement precision
If multiple sensors are deployed to detect ice level at different positions, then the system can detect ice bridging and uneven distribution, but the system complexity and cost increase
Solution Approach 1:
The patent designs a single capacitive sensor that performs multiple functions simultaneously: it detects ice level, identifies ice bridging conditions, and determines uneven ice distribution. The multi-zone capacitive sensing array provides all these measurements through one integrated sensor assembly, eliminating the need for multiple separate sensor systems and reducing overall complexity.
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 system provides reliable, accurate, and detailed ice level detection, resistant to frost buildup and ice bridging, with reduced manufacturing complexity and cost, ensuring precise control of ice makers.
Implementation Method 1
capacitive sensing technology is based on detecting changes in the capacitance of an electrode in a circuit
Implementation Method 2
The capacitance measured on an electrode depends on the dielectric constant of the space around the electrode through which an electric field passes. Since there is a difference between the dielectric constants of air and ice, capacitive sensing technology can detect differences in the amounts of ice and air within a distance of the electrodes
Data Source
AI summary
An ice level sensor in an appliance that includes an ice storage housing and an ice maker. The housing receives ice from the ice maker. The ice level sensor includes a control circuit and one or more electrode arrays capable of detecting ice in the housing. The electrode arrays each contain one or more sense electrodes, and the control circuit detects ice in the housing based on a measurement of capacitance of the sense electrode(s). When the sensor detects that ice in the housing has reached a threshold level, the sensor can stop the ice maker from depositing more ice into the housing, to prevent overflow. The ice level sensor detects that ice has reached a threshold level by detecting changes in capacitance of a sense electrode or by detecting that the capacitance of a sense electrode reached a predetermined value.