Light-Emitting Element with Temperature Compensation for Reference Light Source
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Solution Overview
Problem
In the weak light region corresponding to femto to milli W, it is challenging to accurately evaluate the absolute light quantity of a luminous body due to variations in temperature and the lack of suitable reference light sources, leading to unreliable measurements.
Innovation Solution
A light-emitting element with a Lambert's or uniform isotropic emission angle distribution is used as a reference source, equipped with a temperature sensor and controller to adjust its brightness, ensuring consistent light emission despite environmental temperature changes, and is integrated into a system for precise light quantity measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional light source is used for measurement in the weak light region, then the measurement system is simple, but the measurement precision deteriorates due to temperature variation affecting the reference light source
Solution Approach 1:
The patent applies parameter changes by actively controlling the drive current or voltage of the light-emitting element based on temperature sensor feedback. The controller adjusts electrical parameters (current/voltage) to compensate for temperature-induced brightness variations, maintaining stable reference light output across different environmental temperatures.
Solution Approach 2:
The patent implements feedback control by using a temperature sensor to continuously monitor the light-emitting element's temperature and feeding this information back to the controller. The controller then adjusts the drive parameters accordingly, creating a closed-loop system that automatically compensates for temperature effects on light output.
2Illumination intensity
If the brightness of the light-emitting element is increased to improve signal strength, then the measurement sensitivity improves, but the temperature variation effect on brightness becomes more significant
Solution Approach 1:
The patent uses parameter changes to dynamically adjust the drive current or voltage based on temperature conditions. When temperature increases cause brightness to drop, the controller increases the drive parameters to maintain the desired light output level, effectively decoupling the reference light intensity from temperature variations.
Solution Approach 2:
The system applies preliminary anti-action by preemptively adjusting the drive parameters in response to temperature changes before they significantly affect the measurement. The temperature sensor detects changes and the controller compensates by adjusting brightness, counteracting the temperature effect before it degrades measurement accuracy.
3Reliability
If a temperature compensation system is added to the light source, then the measurement reliability improves, but the device complexity increases
Solution Approach 1:
The patent employs feedback control with a temperature sensor and controller to monitor and adjust the light-emitting element's operating conditions. This closed-loop system automatically compensates for temperature effects, providing reliable measurements while keeping the complexity manageable through the use of standard sensor and controller components.
Solution Approach 2:
The controller serves multiple functions: it drives the light-emitting element, reads temperature sensor data, processes the feedback information, and adjusts drive parameters accordingly. By making the controller multi-functional, the patent reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving temperature compensation.
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 allows for accurate evaluation of absolute light quantities in the weak light region, providing reliable and consistent measurements by stabilizing the light emission and accounting for temperature variations.
Implementation Method 1
a light-emitting element, wherein a light whose emission angle distribution is one of Lambert's emission distribution (based on Lambert's emission law) or uniform Isotropic emission distribution (uniform Isotropic emission), is extracted from a light extraction opening window
Implementation Method 2
a temperature sensor configured to measure a temperature of the light-emitting element
Implementation Method 3
based on temperature information received from the temperature sensor, the controller is configured to vary a current value or a voltage value for driving the light-emitting element by the light-emitting element drive part, so as to suppress a variation of the brightness of a light-emitting surface
Data Source
AI summary
A light-emitting element, in which a light whose emission angle distribution is one of Lambert's emission law or uniform Isotropic emission, is extracted from a light extraction opening window, and an in-plane distribution of a light intensity on a light extraction surface of the light extraction opening window is uniform, and which can be used as a reference light source when measuring an absolute light quantity of a weak light emitted from a luminous body which is a measurement object.