Biological Information Measuring Apparatus DC Component Removal
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Solution Overview
Problem
Conventional biological information measuring apparatuses face challenges with DC component variations and inefficient frequency usage due to spectrum spreading, leading to inaccurate measurements of biological information within living organisms.
Innovation Solution
The apparatus employs a light emission section that modulates signals using spread-spectrum techniques with specific frequencies to minimize DC components and optimize frequency usage, and a light detection section that removes DC components and higher frequency signals to enhance signal reproduction and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If spread-spectrum modulation is used to measure biological information, then the measurement can be performed noninvasively, but DC component variations affect measurement accuracy
Solution Approach 1:
The patent extracts and removes the DC component from the detected light signal through a dedicated DC component removal unit. This separates the harmful DC variations from the useful AC signal containing biological information, allowing noninvasive measurement to proceed without accuracy degradation from DC drift and offset variations.
Solution Approach 2:
The patent transforms the light signal from the time domain to the frequency domain through Fourier transformation, and then selectively removes the DC component (zero frequency) while preserving the AC components containing biological information. This parameter transformation in the frequency domain enables precise separation and elimination of the harmful DC variations.
2Productivity
If spread-spectrum modulation is used, then light can be emitted for measurement, but frequency usage efficiency is low due to DC and near-DC components
Solution Approach 1:
The patent extracts and eliminates the DC and near-DC frequency components from the spread-spectrum modulated light signal before detection. By removing these inefficient frequency components that carry no useful biological information, the system improves frequency usage efficiency and reduces energy waste while maintaining effective measurement capability.
Solution Approach 2:
The patent employs periodic modulation of the light source at frequencies above the DC region, using spread-spectrum modulation with a pseudorandom code sequence. This periodic action concentrates the useful signal energy in the AC frequency range, improving frequency usage efficiency by avoiding the inefficient DC and near-DC regions.
3Ease of manufacture
If sampling frequency matches light emission period, then conversion can be performed, but detection signal cannot be sampled over entire signal band
Solution Approach 1:
The patent transforms the detection signal from the time domain to the frequency domain using Fourier transformation. This parameter change allows the system to identify and process the entire signal band effectively, ensuring that all frequency components containing biological information are captured and reconstructed, thereby preventing information loss.
Solution Approach 2:
The patent uses the known spread-spectrum modulation code as a reference for correlation detection. By comparing the detected signal with the transmitted code sequence, the system can accurately reconstruct the original biological information signal across the entire signal band, compensating for any sampling limitations and preventing information loss.
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
This approach effectively eliminates DC-related measurement issues and improves the efficiency of frequency usage, resulting in more accurate biological information acquisition, including density, oxygen saturation, glucose levels, and pulse measurements.
Implementation Method 1
measures biological information by making use of spread-spectrum modulation and demodulation... measurement of oxygen level in blood on the basis of a change in absorption of near-infrared light by hemoglobin
Implementation Method 2
a light detection section is configured to convert light having propagated through a living organism to an electrical detection signal (analog signal)
Data Source
AI summary
A light emission section spread-spectrum modulates a base band signal at a chip frequency f to thereby generate a primary modulated signal, modulates the primary modulated signal at a frequency 2f to thereby generate a secondary modulated signal, and emits a near-infrared light beam having a specific wavelength into a living organism on the basis of the secondary modulated signal. A light detection section receives a reflected light beam from the interior of the living organism in an effective detection band 2f, converts it to an electrical detection signal, and converts the detection signal to a digital signal at a sampling frequency 4f. The light detection section then demodulates the digital signal at the frequency 2f to thereby generate a primary demodulated signal, and demodulates the primary demodulated signal through spectrum despreading to thereby generate a secondary demodulated signal. Thus, a biological information signal representing biological information is output.