Ultra-Short Throw Projection Lens Temperature Compensation
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Solution Overview
Problem
Ultra-short throw projectors face challenges in maintaining resolution due to imaging surface curvature caused by temperature increases, which existing technologies fail to adequately address, especially in achieving high luminance and compact size with favorable temperature characteristics.
Innovation Solution
A projection device incorporating a dioptric system with positive and negative lenses satisfying specific conditional expressions, combined with a reflection optical system, including a free-form surface concave mirror, to correct temperature-induced focal length changes and imaging surface curvature, achieving high resolution and temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a dioptric system and curved mirror are combined to achieve ultra-short projection distance, then projection distance is shortened, but imaging surface curvature occurs due to temperature increase causing resolution degradation
Solution Approach 1:
The patent applies parameter changes by selecting specific lens materials with appropriate temperature coefficients of refractive index and Abbe numbers that satisfy conditional expressions. This allows the optical system to compensate for temperature-induced focal length changes and imaging surface curvature, maintaining resolution while achieving ultra-short projection distance
Solution Approach 2:
The patent uses composite material principles by combining positive and negative lenses made from different glass materials with specific optical properties. The cemented lens structure integrates materials with complementary temperature characteristics to counteract thermal effects and maintain imaging quality in ultra-short throw configuration
2Stability of the object's composition
If lens materials with specific temperature coefficients are used to compensate for temperature changes, then temperature stability is improved, but device complexity increases due to multiple conditional expressions
Solution Approach 1:
The patent manages complexity by establishing specific parameter ranges for lens materials (temperature coefficient of refractive index between -6 to -4 × 10^-6/K and Abbe number between 70 to 75) that satisfy conditional expressions. These constrained parameters enable temperature compensation while maintaining manageable optical system design
3Illumination intensity
If higher luminance is achieved through increased light source power, then brightness is improved, but temperature increase causes greater focal length changes and imaging surface curvature
Solution Approach 1:
The patent converts the harmful effect of temperature increase into a beneficial compensation mechanism. By using lens materials with specific temperature coefficients, the thermal expansion and refractive index changes are harnessed to counteract imaging surface curvature, allowing high luminance operation without resolution degradation
Solution Approach 2:
The optical system is designed with lens materials whose temperature-dependent optical parameters (refractive index, Abbe number) are specifically selected to compensate for thermal effects. This allows the system to maintain imaging quality even under high luminance conditions that generate significant heat
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 provides a projection device with an ultra-short projection distance, high luminance, and compact size, maintaining resolution and temperature stability across varying conditions.
Implementation Method 1
a dioptric system including at least one positive lens P1 and at least one negative lens N1; and a reflection optical system having at least one reflection optical element
Implementation Method 2
a reflection optical system having at least one reflection optical element
Data Source
AI summary
A projection device to magnify and project, on a screen, an image displayed at an image display element, includes: a dioptric system including at least one positive lens and at least one negative lens; and a reflection optical system having at least one reflection optical element.