Projection Lens Thermal Drift Compensation via Third Lens Focal Length
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Solution Overview
Problem
Large-aperture projection lenses require multiple lenses for optimal imaging quality, but aspherical lenses near the aperture stop are sensitive to imaging quality and temperature changes, making mass production challenging and leading to thermal drift issues.
Innovation Solution
A projection lens configuration with specific refractive powers and focal lengths, including a third lens with a focal length between 20-200 mm, which reduces sensitivity to imaging quality and compensates for thermal expansion by varying optical parameters, improving thermal drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aspherical lenses are used to reduce aberration in large-aperture projection lenses, then optical imaging quality is improved, but sensitivity to imaging quality increases making mass production difficult
Solution Approach 1:
The patent specifies a focal length range for the third lens (20-200mm) and defines specific refractive power signs for each lens element. These parameter ranges create a design space where multiple lens configurations can achieve acceptable imaging quality, reducing sensitivity to manufacturing variations and enabling mass production while maintaining optical performance.
2Manufacturing precision
If aspherical lenses are used to reduce aberration, then optical imaging quality is improved, but thermal drift effect occurs causing blurred projected image at higher temperatures
Solution Approach 1:
The patent defines specific focal length ranges and refractive power characteristics for each lens element that remain stable across temperature variations. By optimizing these parameters within specified ranges, the lens system maintains consistent optical performance and minimizes thermal drift effects.
3Manufacturing precision
If multiple lenses are used in large-aperture projection lens, then optical imaging quality is improved, but device complexity increases
Solution Approach 1:
The patent designs a six-element lens system where each lens element serves multiple optical functions. The specific arrangement and characteristics of each lens contribute to aberration correction, focus control, and thermal stability simultaneously, achieving high imaging quality without excessive complexity.
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 configuration achieves clear imaging quality and increased mass production yield while effectively mitigating thermal drift in optical engines.
Implementation Method 1
compensates an optical effect generated from thermal expansion for the housing
Implementation Method 2
a thermal drift effect may occur accordingly, such that a gradually blurred projected image may been seen after the projector being turned on
Implementation Method 3
The first lens is disposed between the enlarged side and the reduced side and has a negative refractive power. The second lens is disposed between the first lens and the reduced side and has a positive refractive power.
Data Source
AI summary
A projection lens disposed between an enlarged side and a reduced side is provided. The projection lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, which are sequentially arranged from the enlarged side to the reduced side. Refractive powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are respectively negative, positive, positive, negative, positive and positive. A focal length of the third lens is greater than or equal to 20 mm and is less than or equal to 200 mm. An optical engine is also provided.