LED Calibration Current Control for Stable Low-Light Detection
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Solution Overview
Problem
Existing calibration devices for optical detectors in bioluminescent or fluorescent light-based chemical and biological analyses face challenges in providing a stable and reliable calibration due to temperature-dependent LED output variations and complex control circuits, especially when low light levels are required.
Innovation Solution
A system comprising a calibration device with a constant current generator that supplies a low driving current (0.5 to 25 µA, preferably 1.5 to 4.5 µA) to a light-emitting diode, using an electronic circuit with operational amplifiers to stabilize the current, and a setting device for adjusting calibration points, ensuring consistent light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an LED based light source is driven with a constant voltage in the range of several Volts, then the light output is sufficient for calibration, but the temperature rises due to high power consumption which destabilizes the light output
Solution Approach 1:
The patent changes the electrical parameter from constant voltage to constant current control, and reduces the current magnitude from several mA to sub-µA range (0.1-10 µA). This parameter change allows sufficient light output for calibration while minimizing self-heating effects that cause temperature-dependent instability in LED output.
Solution Approach 2:
The patent employs pulsed or intermittent illumination rather than continuous operation. The LED is activated only when calibration measurements are taken, allowing the device to cool down between measurements. This periodic action reduces average power consumption and temperature rise while providing sufficient light output during active measurement periods.
2Illumination intensity
If optical filters or apertures are used to reduce the amount of emitted light, then the light output is reduced to calibration levels, but the device complexity increases
Solution Approach 1:
Instead of adding optical components (filters, apertures) to reduce light output, the patent changes the electrical control parameters of the LED driver. By using constant current control in the sub-µA range, the light output is directly reduced to calibration-appropriate levels without requiring additional optical attenuation components, thereby simplifying the overall device structure.
3Illumination intensity
If a pulsed voltage is used to drive the LED, then the light output is reduced, but the temperature within the device increases and the control circuit becomes complex and expensive
Solution Approach 1:
The patent uses constant current control in the sub-µA range instead of pulsed voltage control. This approach achieves low light output suitable for calibration without the temperature spikes associated with pulsed operation, and avoids the complexity of pulse generation circuits by using a simple constant current generator topology.
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 system provides a stable and reliable calibration by minimizing temperature effects and heat generation, allowing for precise calibration of optical detectors with minimal light output variation, suitable for bioluminescence detection devices.
Implementation Method 1
comprising a light emitting diode, an electronic circuit for driving the light emitting diode
Implementation Method 2
the emission of bioluminescent or fluorescent light has been proven to be a useful tool
Implementation Method 3
the emission of bioluminescent or fluorescent light has been proven to be a useful tool
Data Source
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AI summary
The present invention provides a calibration device for an optical detector comprising a light emitting diode (1), and an electronic circuit (3) for driving the light emitting diode (1), wherein the electronic circuit (3) is a constant current generator configured to supply a constant driving current to the light emitting diode (1) in the range of 0.5 to 25 μΑ. Furthermore, the present invention provides a setting device for setting at least one calibration point for a calibration device as described above. The setting device comprises a light detector configured to output a signal representing the light emission intensity of a calibration device under examination, a controller for controlling the constant driving current of the calibration device under examination, and a calibration point setting means for setting at least one calibration point for the calibration device under examination. The calibration device comprises a setting unit (11) for setting the driving current, the setting unit further comprising an interface (13) for connecting the setting device.