LED Array Layout for Wavelength Uniformity in Exposure Light Sources
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Solution Overview
Problem
The use of LED arrays in exposure apparatuses leads to wavelength unevenness due to temperature dependency among LEDs, affecting illuminance uniformity and resolution, which existing techniques like Japanese Patent Laid-Open No. 2024-035053 fail to address effectively.
Innovation Solution
The arrangement of LEDs in a matrix with different temperature characteristics, aligning peak wavelengths by positioning LEDs with longer wavelengths in cooler regions and shorter wavelengths in warmer regions, and using a coolant system to manage temperature uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a plurality of LEDs are used as the light source, then the total light output is sufficient, but wavelength unevenness occurs due to temperature dependency
Solution Approach 1:
The patent applies local quality by assigning different initial peak wavelengths to LEDs based on their position in the array. LEDs in the central region are designed with longer peak wavelengths, while LEDs in the peripheral region are designed with shorter peak wavelengths. This local differentiation compensates for the temperature-induced wavelength shifts, as the central region experiences higher temperatures and thus requires longer initial wavelengths to maintain uniformity after thermal expansion.
2Ease of operation
If individual current control is applied to each LED, then light output can be adjusted, but temperature unevenness occurs leading to wavelength variation
Solution Approach 1:
The patent implements preliminary action by pre-configuring the LEDs with different initial peak wavelengths according to their positions in the array before operation. This preliminary arrangement of wavelength characteristics compensates for the temperature distribution that will occur during operation, eliminating the need for complex real-time individual current control to maintain wavelength uniformity.
3Illumination intensity
If high degree of integration is used in LED array, then total luminance increases, but heat generation increases causing temperature unevenness
Solution Approach 1:
The patent addresses temperature uniformity by implementing local quality in the wavelength characteristics of LEDs. The central region LEDs are designed with longer peak wavelengths to compensate for the higher temperatures expected in that region due to heat accumulation from high integration. This local differentiation maintains overall wavelength uniformity across the array despite the temperature gradient caused by high integration density.
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 arrangement reduces wavelength unevenness, ensuring consistent peak wavelengths and improving resolution and illuminance in the exposure apparatus.
Implementation Method 1
a coolant system to manage temperature uniformity
Implementation Method 2
a first light emitting element and a second light emitting element that differ from each other in peak wavelength when a current flows
Data Source
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AI summary
A light source apparatus includes an element array in which a plurality of light emitting elements are arrayed, wherein the plurality of light emitting elements include a first light emitting element, and a second light emitting element having temperature characteristic, which indicates a relationship between an element temperature and a peak wavelength, different from a temperature characteristic of the first light emitting element, and the first light emitting element and the second light emitting element are arrayed in accordance with temperature unevenness in the element array.