Double-Bearing Position Encoder for Pulse Oximetry
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Solution Overview
Problem
Single-bearing encoder wheels in pulse oximetry systems lack mechanical stability, leading to inaccuracies in measuring and controlling the phase and frequency of active pulses, which affects the precision of optical sensor measurements.
Innovation Solution
A double-bearing position encoder design is implemented, featuring a housing with two bearings to stabilize the axle, an encoder wheel with slots, and an LED for illumination, which enhances the accuracy of active pulse generation and measurement by improving encoder wheel stability and resolving configuration issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-bearing encoder wheel is used, then the device complexity is reduced, but the mechanical stability deteriorates leading to inaccuracies in measuring phase and frequency
Solution Approach 1:
The encoder support structure is segmented into two separate bearings instead of a single bearing, with each bearing supporting one end of the encoder wheel axle. This segmentation provides more comprehensive mechanical support and stability while maintaining reasonable device complexity.
2Measurement precision
If a double-bearing position encoder is implemented, then the mechanical stability and measurement precision are improved, but the device complexity increases
Solution Approach 1:
The second bearing is extracted and positioned at the opposite end of the encoder wheel axle from the first bearing. This extraction approach provides balanced mechanical support and stability while keeping the overall structure relatively simple and manageable.
3Stability of the object's composition
If the encoder wheel is stabilized with a second bearing, then the mechanical stability is improved, but configuration issues and manufacturing difficulty increase
Solution Approach 1:
The two bearings are positioned at opposite ends of the encoder wheel axle, providing localized support at critical points. This local quality approach ensures maximum stability with minimal structural complexity and facilitates easier manufacturing and assembly.
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 double-bearing position encoder provides improved mechanical stability, resulting in more accurate control of active pulse frequency and phase, enhancing the precision of optical sensor measurements and addressing the stability issues of single-bearing systems.
Implementation Method 1
An LED is disposed within the housing so as to illuminate the encoder wheel
Implementation Method 2
A detector is responsive to the LED illumination after optical interaction with the wheel slots as the axle rotates the wheel so as to indicate the wheel position
Data Source
AI summary
A double-bearing position encoder has an axle stabilized within a housing via two bearings disposed on opposite walls of the housing. The axle is in communications with a rotating cam. The cam actuates a pulser so as to generate an active pulse at a tissue site for analysis by an optical sensor. The axle rotates a slotted encoder wheel or a reflective encoder cylinder disposed within the housing so as to accurately determine the axle position and, hence, the active pulse frequency and phase.