Finger Contact Structure for Accurate Optical Biometric Detection
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Solution Overview
Problem
Existing biological information detection devices suffer from reduced detection accuracy due to excessive pressing force on the finger, which can crush blood vessels and introduce air layers, leading to sensitivity loss and inaccurate pulse wave signal detection.
Innovation Solution
A biological information detection device with a housing that includes a light-transmissive member and a pressing force suppression unit formed from a harder material, featuring a design with inclined sections to evenly distribute pressure and prevent vessel crushing and air interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the outer surface of the light-transmissive plate protrudes from the outer surface of the sensor frame, then the light-transmissive plate applies pressing force to the finger, but this causes blood vessel crushing and reduced detection accuracy
Solution Approach 1:
The pressing force suppression unit is divided into multiple inclined sections (first inclined section and second inclined section) that distribute the pressing force across different areas. This segmentation prevents concentration of force on a single point, avoiding blood vessel crushing while maintaining adequate contact pressure for light transmission.
Solution Approach 2:
The pressing force suppression unit is positioned specifically at the peripheral portion of the light-transmissive plate, leaving the central measurement area unaffected. This local application of force suppression maintains optimal pressure where light transmission occurs while preventing harmful pressure at the edges.
2Shape
If the outer surface of the sensor frame protrudes from the outer surface of the light-transmissive plate, then an air layer intervenes between the finger and the light-transmissive plate, but this reduces sensitivity and detection accuracy
Solution Approach 1:
The pressing force suppression unit with its inclined sections makes contact with the finger first, gradually guiding the finger surface into close contact with the light-transmissive plate. This preliminary action prevents air layer formation by ensuring progressive, controlled contact rather than sudden impact.
Solution Approach 2:
The inclined sections provide a curved, gradual transition surface that facilitates smooth contact between the finger and the light-transmissive plate. This curved geometry helps eliminate air pockets by distributing contact pressure gradually across the interface.
3Device complexity
If a flat sensor frame surface is used, then the structure is simple, but the pressing force is concentrated and detection accuracy is reduced
Solution Approach 1:
The pressing force suppression unit replaces the flat sensor frame surface with inclined sections that create a gradual, curved transition. This curved geometry distributes pressing force across multiple areas rather than concentrating it, improving detection accuracy while adding only moderate structural complexity.
Solution Approach 2:
The pressing force suppression unit extends in the height direction (Z-axis) with inclined sections, adding a vertical dimension to the previously flat surface. This dimensional addition allows force distribution across multiple height levels, reducing pressure concentration while maintaining structural integrity.
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 device ensures accurate detection of biological information by maintaining optimal pressure on the subject, preventing blood vessel crushing and air interference, thereby enhancing sensitivity and accuracy.
Implementation Method 1
a light-transmissive member disposed at a side of the housing surface of the housing, and having a planar portion that is configured to transmit the light from the subject
Data Source
AI summary
A biological information detection device includes a housing having a planar housing surface, a detection unit having a light receiving portion, a light-transmissive member having a planar portion, and a pressing force suppression unit disposed on the housing surface to surround the planar portion, and suppressing a pressing force applied to a subject by the planar portion. The pressing force suppression unit is formed using a material harder than the subject. A height of the pressing force suppression unit from the housing surface is higher than a height of the planar portion with reference to the housing surface. The pressing force suppression unit has a first inclined section in which the height of the pressing force suppression unit increases continuously or in a stepwise manner from an inner periphery side toward an outer periphery side.