Mattress Capacitance Sensor System for Sleeping Position Detection
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Solution Overview
Problem
Existing methods for detecting a user's sleeping position on a mattress face challenges such as poor vibration transmission with thick mattresses, high costs and sensor strain, narrow detection ranges, and interference from metallic bed components, limiting accurate and reliable position detection.
Innovation Solution
A mattress system incorporating conductive sheets, an elastic body, and a capacitance measurement unit, which deforms under user load, allowing for precise position judgment without requiring additional bed frame sensors, reducing apparatus size and cost, and minimizing sensor deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vibration-based sensors are used to detect sleeping position, then detection capability is provided, but detection accuracy deteriorates with thick mattresses due to poor vibration transmission
Solution Approach 1:
The patent replaces vibration-based mechanical detection with capacitance-based electrical field detection. The capacitance sensor detects changes in electrical field caused by the user's body position, eliminating the need for mechanical vibration transmission through the mattress. This substitution resolves the contradiction by maintaining detection capability while achieving accurate position measurement regardless of mattress thickness.
Solution Approach 2:
The patent introduces an elastic body as an intermediary between the capacitance sensor and the user's body. This elastic body deforms under the user's weight, bringing the conductive sheet closer to the body and enhancing capacitance changes. This intermediary mechanism improves measurement precision while maintaining reliability across different mattress configurations.
2Reliability
If load sensors are provided on the bed apparatus to detect sleeping position, then position detection is enabled, but apparatus cost and complexity increase
Solution Approach 1:
The patent merges the mattress structure with the sensing function by integrating a conductive sheet directly into the mattress layers. This combination eliminates the need for separate load sensors on the bed apparatus, reducing device complexity while maintaining position detection capability. The mattress itself becomes the sensing element through capacitance measurement.
Solution Approach 2:
The capacitance sensor system serves multiple functions: it detects sleeping position, calculates user weight, and monitors body contact area. This multi-functionality replaces the need for multiple specialized sensors, reducing overall apparatus complexity while maintaining comprehensive detection capability.
3Measurement precision
If additional bed frame sensors are added to improve detection accuracy, then measurement precision improves, but apparatus size and cost increase
Solution Approach 1:
The patent extracts the sensing function from the bed frame structure and relocates it entirely to the mattress. By removing the need for bed frame sensors and implementing capacitance-based detection within the mattress layers, the apparatus size is reduced while maintaining or improving measurement precision through direct contact sensing.
4Strength
If metallic components are present in the bed structure, then structural strength is provided, but sensor detection accuracy deteriorates due to electromagnetic interference
Solution Approach 1:
The patent introduces an elastic body as an electrical insulating intermediary between the conductive sheet and any metallic components. This intermediary layer prevents electromagnetic interference from metallic bed structures while allowing mechanical deformation to be transmitted, thereby maintaining measurement precision without compromising structural strength.
Solution Approach 2:
The conductive sheet is implemented as a flexible thin film integrated into the mattress layers. This thin film structure is electrically isolated from metallic components by the surrounding elastic materials, preventing interference while maintaining the necessary flexibility for capacitance-based detection of body position changes.
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 reliable detection of user position and posture with a wide detection range, reduced risk of sensor drift, and accurate weight calculation, while avoiding the limitations of existing methods.
Implementation Method 1
a measurement unit that measures a change of capacitance of the conductive sheet observed when the elastic body is deformed
Implementation Method 2
an elastic body that is adjacent to the conductive sheet
Data Source
AI summary
A mattress including: an elastic body; a sheet that is disposed at least above the elastic body and made of any of a conductive sheet and a conductive fiber; and a measurement unit that is configured to measure a change of capacitance of the sheet observed when the elastic body is deformed.