Contactless Current Sensing for Light Source Power Monitoring
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Solution Overview
Problem
Conventional methods for monitoring the optical output power of a light source, such as using monitor photodiodes or shunt resistors, suffer from power loss, heat dissipation issues, and increased complexity, which are particularly problematic in mobile applications.
Innovation Solution
An illumination device that includes a light source, a current path for the supply current, a contactless sensor to measure the current strength, and processing circuitry to determine the optical output power based on the measured current strength, thereby eliminating the need for shunt resistors and monitor photodiodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shunt resistor is used to sense the laser diode forward current, then the optical output power can be monitored, but considerable energy loss and heat dissipation occur
Solution Approach 1:
The patent replaces the electrical measurement system (shunt resistor) with an optical measurement system (photodiode). The photodiode converts a small fraction of the optical output power directly into current or voltage signals for monitoring, eliminating the need for electrical current sensing through resistors and thus avoiding the associated power losses and heat generation.
Solution Approach 2:
The patent introduces a photodiode as an intermediary element that senses the optical output power directly. This intermediary converts optical energy into electrical signals for monitoring purposes, allowing accurate measurement without interfering with the main illumination circuit and avoiding the harmful effects of shunt-based measurement.
2Measurement precision
If a monitor photodiode is integrated inside the illumination module, then direct sensing of optical output power is achieved, but additional readout circuitry and installation complexity are required
Solution Approach 1:
The patent makes the photodiode serve multiple functions: it acts as both the monitoring sensor and provides a built-in signal processing capability through its direct conversion of optical power to electrical signals. This multi-functionality reduces the need for separate readout circuitry and simplifies the overall system architecture.
3Measurement precision
If conventional monitoring methods are used, then optical output power can be measured, but power consumption increases and battery life decreases
Solution Approach 1:
The patent replaces energy-intensive electrical current sensing with optical energy harvesting. The photodiode utilizes a small fraction of the existing optical output power to generate the measurement signal, eliminating the need for additional power consumption and thereby extending battery life in mobile applications.
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 solution allows for efficient monitoring of optical output power with minimal power consumption and reduced heat dissipation, leading to improved battery life and reduced complexity in mobile applications.
Implementation Method 1
a sensor configured to contactlessly measure a current strength of the supply current in the current path
Data Source
AI summary
An illumination device is provided. The illumination device includes a light source and a current path configured to transport a supply current to the light source. Further, the illumination device includes a sensor configured to contactlessly measure a current strength of the supply current in the current path and to output a measurement signal indicative of the measured current strength. The illumination device additionally includes processing circuitry coupled to the sensor and configured to determine the optical output power of the light source based on the measured current strength indicated by the measurement signal.