LED Optical Output Control with Updatable Temperature Coefficients
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Solution Overview
Problem
Existing optical output control systems for LEDs face challenges in achieving high accuracy and quick responsiveness due to individual differences among light source devices and changes in characteristics over time, and conventional feedforward methods require extensive data tables and processing, making them unsuitable for applications requiring fine optical output adjustments.
Innovation Solution
An optical output control system that uses a control unit to determine current amounts based on a defined relationship among optical output, environmental temperature, and current supply, with coefficients that can be updated to account for individual device differences and changes, allowing for high accuracy and responsiveness through simple arithmetic processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a data table with relationship among optical output, temperature, and current is used for feedforward control, then optical output control accuracy is improved, but device complexity and data processing requirements increase significantly
Solution Approach 1:
The patent transforms the complex three-dimensional relationship (optical output, temperature, current) into a simplified linear model using temperature compensation coefficients. Instead of storing extensive data tables, the system uses a mathematical expression with coefficients that are determined through measurement and stored in a register, dramatically reducing data storage and processing requirements while maintaining control accuracy.
Solution Approach 2:
The patent extracts the essential temperature compensation characteristics from the complex data table and represents them through a simplified mathematical model. By taking out only the critical compensation coefficients rather than storing complete data tables, the system achieves accurate control with minimal data storage and processing complexity.
2Measurement precision
If a large data table is used for accurate optical output control, then control precision is improved, but processing speed decreases due to extensive data reading and complement processing
Solution Approach 1:
The patent changes the control approach from extensive data table lookup to a simple linear calculation using temperature compensation coefficients. This parameter transformation enables the system to quickly compute the required current adjustment based on temperature changes, achieving fast responsiveness while maintaining accurate optical output control.
3Ease of operation
If conventional feedforward control is used without considering individual device differences, then ease of operation is improved, but optical output control accuracy deteriorates due to individual differences and characteristic changes over time
Solution Approach 1:
The patent applies local quality by determining specific temperature compensation coefficients for each individual light source device based on its unique characteristics. Instead of using a universal control approach, the system measures and stores device-specific coefficients that account for individual differences and characteristic changes over time, enabling accurate control while maintaining ease of operation through automated coefficient determination.
4Stability of the object's composition
If feedback control using a photosensor is used, then optical output stabilization is improved, but control accuracy deteriorates because the photosensor itself is affected by temperature
Solution Approach 1:
The patent introduces temperature compensation coefficients as an intermediary that mediates between temperature changes and optical output control. Instead of directly measuring optical output with a temperature-sensitive photosensor, the system uses temperature measurements combined with compensation coefficients to calculate the required current adjustment, eliminating the temperature sensitivity problem of the photosensor while maintaining stabilization capability.
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 achieves high accuracy and quick responsiveness in controlling optical output by updating coefficients based on device characteristics, addressing individual differences and temporal changes, even with a smaller amount of data than conventional methods.
Implementation Method 1
a temperature detecting unit that detects an environmental temperature of the light source unit
Implementation Method 2
a light-emitting element such as a light-emitting diode (LED) varies in an amount of light emission depending on the temperature even when the same amount of electric current is applied
Implementation Method 3
a part of emitted light from the LED is received by a photosensor, and the amount of current supplied from a power supply circuit to the LED is adjusted on the basis of the amount of received light
Data Source
AI summary
An optical output control system includes: a light source unit; a current supply unit supplying current to the light source unit; a temperature detecting unit detecting an environmental temperature of the light source unit; and a control unit controlling a current amount supplied from the current supply unit to the light source unit on the basis of an execution control function in which a relationship among a first variable corresponding to a target value related to optical output of the light source unit, a second variable corresponding to the environmental temperature detected by the temperature detecting unit, and a third variable corresponding to the current amount supplied to the light source unit is defined by using one or a plurality of coefficients. The control unit can update at least one of the coefficients constituting the execution control function on the basis of coefficient update information that is input.