Pulse Oximeter LED Driver With Inductor Charge Recycling
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Solution Overview
Problem
Existing photometry systems waste significant power due to the use of linear LED drivers and voltage regulating elements, leading to inefficiencies and reduced measurement accuracy in determining peripheral oxygen saturation.
Innovation Solution
Implementing an inductor-based driver system that eliminates linear LED drivers and voltage regulators, utilizing variable amplitude current pulses and charge recycling to reduce power consumption and enhance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If linear LED drivers and voltage regulating elements are used in photometry systems, then the system can provide stable power to light emitting elements, but a large amount of power is wasted in the electronics (e.g., 100 mW wasted in LED driver while 150 mW provided to light emitting elements)
Solution Approach 1:
The patent removes the linear LED driver and voltage regulating elements from the photometry system, extracting only the essential power delivery function. The simplified system uses a power supply directly coupled to light emitting elements through a current driver, eliminating the intermediate regulation stages that caused power loss while maintaining adequate power delivery for accurate measurements.
Solution Approach 2:
The patent changes the power delivery parameters by using pulse-width modulation (PWM) instead of linear voltage regulation. The system switches between power supply states (on/off) at high frequencies, effectively delivering average power to light emitting elements while minimizing energy loss in the power delivery path, thereby reducing power waste without compromising measurement stability.
2Loss of energy
If an inductor based driver is used to reduce power waste, then power consumption is reduced, but the system complexity changes requiring variable amplitude current pulses and charge recycling mechanisms
Solution Approach 1:
The patent employs periodic pulse-width modulation to control the light emitting elements. The system uses periodic switching of the power supply through a current driver, creating variable amplitude current pulses that drive the LEDs. This periodic action enables efficient power delivery while allowing the inductor to recycle charge, reducing overall power waste without requiring complex continuous regulation circuitry.
Solution Approach 2:
The patent implements charge recycling through the inductor, recovering energy that would otherwise be wasted. The inductor stores energy during portions of the cycle and releases it during other portions, effectively recycling charge and reducing the total power required from the supply. This energy recovery mechanism reduces power waste while the periodic nature of the operation keeps the control electronics relatively simple.
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 inductor-based driver system reduces power waste, maintains measurement accuracy, and improves the precision of peripheral oxygen saturation determination by compensating for voltage variations.
Implementation Method 1
an inductor, such as can be coupled to the first and second LEDs, such as to store energy associated with at least one of the first and second currents
Implementation Method 2
a first LED, such as to emit light to a target in response to a first current through the first LED
Implementation Method 3
a light source (e.g., an LED)
Implementation Method 4
a photosensitive element, such as to receive emitted light from the first LED and the second LED
Data Source
AI summary
A photometry device can include a first LED to emit light to a target in response to a first current through the first LED, a second LED to emit light to the target in response to a second current through the second LED, and an inductor, coupled to the first and second LEDs, to store energy associated with at least one of the first and second currents.