Refrigerator Dispenser Capacitive Sensing for Overflow Prevention
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Solution Overview
Problem
Existing refrigerator dispensers face issues with mechanical wear, high complexity and cost due to mechanical and membrane switches, and lack of automatic cut-off and differentiation between animate and inanimate objects, leading to potential overfilling and accidental dispensing.
Innovation Solution
A passive capacitive sensor system that detects the presence and size of a container, automatically initiates and terminates dispensing operations, and differentiates between animate and inanimate objects to prevent accidental dispensing, using capacitive sensors to monitor changes in capacitance for precise control and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical or membrane switches are used to control dispensing, then the dispenser can be operated reliably, but the switches wear out over time requiring replacement and increase system complexity
Solution Approach 1:
The patent replaces mechanical switches and membrane switches with a capacitive sensor system that detects container presence and liquid level through electrical capacitance changes. This eliminates mechanical contact points, springs, and levers that wear out, while reducing system complexity by using a single sensor type for multiple functions (container detection, liquid level measurement, and automatic dispensing control).
2Ease of operation
If buttons or switches are provided for dispensing control, then users can select dispensing operations, but children may play with controls causing accidental dispensing
Solution Approach 1:
The capacitive sensor system automatically detects when a container is present and when the liquid reaches the appropriate level, then autonomously controls the dispensing operation without requiring user interaction with buttons or switches. The system serves itself by monitoring container presence and liquid level continuously, eliminating the need for manual control elements that children could accidentally activate.
3Extent of automation
If active sensors are used to detect container presence, then automatic dispensing can be initiated, but the sensors cannot differentiate between containers and children's hands
Solution Approach 1:
The capacitive sensor system measures local electrical properties (capacitance) at different locations and depths within the dispenser well. By analyzing the spatial distribution and magnitude of capacitance changes, the system can distinguish between the dielectric properties of a container versus a human hand, enabling accurate object differentiation while maintaining automatic dispensing initiation capability.
4Difficulty of detecting and measuring
If active sensors with signal sending and receiving are used, then container detection is possible, but periodic alignment is required and component count increases
Solution Approach 1:
The patent extracts and eliminates the complex signal sending and receiving components of active sensors, retaining only the passive capacitive sensing element. This single capacitive sensor provides container detection functionality without requiring periodic alignment or multiple components, significantly reducing device complexity while maintaining detection capability.
5Productivity
If the dispenser operates without automatic cut-off, then continuous dispensing is possible, but the container may overflow causing waste
Solution Approach 1:
The capacitive sensor continuously monitors the liquid level in the container during dispensing operations and provides real-time feedback to the control system. When the liquid reaches a predetermined level, the sensor detects the change in capacitance and automatically signals the control system to terminate dispensing, preventing overflow while maintaining continuous operation capability throughout the filling process.
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 capacitive sensor system reduces wear and tear, eliminates accidental dispensing, and provides a continuous 'child lock-out' feature without user inconvenience, while minimizing power and component requirements, ensuring accurate filling and safe operation.
Implementation Method 1
A sensor system including at least one passive sensor, such as a capacitive sensor, mounted in the dispenser well
Implementation Method 2
the sensor is configured to detect an upper edge portion of a container placed in the dispenser well and a level of liquid filling the container
Data Source
AI summary
A refrigerator includes a dispenser, a dispenser well, a control for regulating a dispensing operation, and a sensor system for automatically initiating and terminating the dispensing operation. The sensor system includes at least one capacitive-type sensor mounted in the dispenser well. The sensor is configured to detect the presence of a container in the dispenser well, an upper edge portion of the container and a level of liquid filling the container during the dispensing operation. The sensor signals the control to automatically cease the dispensing operation before the level of liquid reaches the upper edge portion of the container. The control is configured to differentiate between animate and inanimate objects, while preventing any release of water or ice when an animate object is detected.