Projection Lens Thermal Stability via dn/dt Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-brightness image projection devices face challenges in maintaining image quality due to temperature changes, which cause shifts in focus position and aberrations, leading to unstable performance and degraded image quality.
Innovation Solution
A projection lens system with specific configurations of positive and negative lenses, including conditions for internal transmittance, linear expansion coefficients, and temperature coefficients, is designed to reduce the influence of heat and stabilize the system's performance, improving image quality by correcting aberrations and maintaining focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the brightness of the image projection device is increased, then the illumination intensity is improved, but the temperature increases causing focus position shift and aberrations
Solution Approach 1:
The patent applies parameter changes by selecting lens materials with specific temperature coefficients of refractive index (dn/dt) and linear expansion coefficients (α) within defined ranges. This allows the optical system to maintain stable focus position and aberration characteristics even when temperature increases due to higher brightness operation, as the controlled material parameters compensate for thermal effects.
Solution Approach 2:
The patent uses composite material strategies by combining multiple lens materials with different thermal properties in the optical system. Specifically, it employs positive lenses and negative lenses with carefully selected dn/dt and α values to create a composite optical system where thermal expansion and refractive index changes of different materials offset each other, maintaining image quality at high brightness levels.
2Illumination intensity
If the brightness of the image projection device is increased, then the illumination intensity is improved, but the image quality deteriorates due to aberrations
Solution Approach 1:
The patent maintains image quality at high brightness by changing material parameters - specifically selecting lenses with controlled dn/dt and α values. This ensures that even under thermal stress from high illumination, the optical system maintains proper focus and minimal aberrations, preserving image quality.
Solution Approach 2:
The patent converts the harmful thermal effects into a beneficial balancing mechanism. By selecting materials with specific thermal properties, the heat-induced changes in one lens are compensated by opposite changes in another lens, turning the potential harm of temperature rise into a self-correcting system that maintains image quality.
3Illumination intensity
If the brightness of the image projection device is increased, then the illumination intensity is improved, but the performance becomes unstable due to temperature changes
Solution Approach 1:
The patent achieves performance stability at high brightness by carefully selecting lens materials with specific dn/dt and α parameters within defined ranges. These controlled parameter changes ensure that thermal expansion and refractive index variations remain within acceptable limits, maintaining consistent optical performance.
Solution Approach 2:
The patent uses composite material combinations with complementary thermal properties to achieve stable performance. The combination of positive and negative lenses with carefully selected dn/dt and α values creates a thermally stable optical system where material expansions and refractive index changes balance each other, ensuring reliable performance under varying temperature conditions.
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 solution effectively reduces the impact of heat on the projection lens system, stabilizing performance and enhancing image quality by ensuring high internal transmittance, controlling thermal expansion, and offsetting refractive index changes, thereby maintaining image clarity even at high brightness levels.
Implementation Method 1
Projection lens system that projects an image of a reduction side into a magnification side
Implementation Method 2
αn1 indicates a linear expansion coefficient of the lens material of the first negative lens at room temperature
Implementation Method 3
dn/dt indicates a temperature coefficient of a relative refractive index of a lens material of the at least one positive lens at room temperature
Data Source
AI summary
A projection lens system that projects an image of a reduction side into a magnification side includes a diaphragm, a plurality of positive lenses, and a plurality of negative lenses. The plurality of positive lenses include a first positive lens closer to the magnification side than the diaphragm is and closest to the diaphragm, a second positive lens second closest to the diaphragm after the first positive lens on the magnification side, a third positive lens closer to the reduction side than the diaphragm is and closest to the diaphragm. The plurality of negative lenses include a first negative lens closer to the magnification side than the diaphragm is and closest to the diaphragm, and a second negative lens closer to the reduction side than the diaphragm is and closest to the diaphragm. The lenses have transmittances larger than threshold values, respectively.