Single Lens Image Pickup Design for Back Focus and Reflow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Compact image pickup lenses for solid-state image pickup devices, such as 1/10-inch or 1/12-inch devices, face challenges with dust contamination due to narrow light flux, and existing biconvex lenses provide insufficient back focus.
Innovation Solution
An image pickup lens design featuring an aperture stop and a single lens, with specific conditional formulae for focal length and shaping factor, and made of heat-resistant energy-curable resin, to achieve sufficient back focus and telecentric property, while allowing for a reflow process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact image pickup lens is made with a single biconvex lens to reduce size and cost, then the lens becomes more compact and cheaper, but the back focus becomes insufficient and dust contamination influence increases
Solution Approach 1:
The patent changes the parameters of the single lens by introducing an aspherical shape with specific curvature values (r1 and r2) and controlling the thickness (d), refractive index (nd), and Abbe number (νd) within defined ranges. These parameter changes enable the lens to achieve both compact size and sufficient back focus, resolving the contradiction between miniaturization and optical performance reliability.
Solution Approach 2:
The patent employs a composite lens structure combining a plastic lens with specific optical properties (nd: 1.50-1.65, νd: 20-40) and an aspherical shape. This composite approach allows optimization of both mechanical compactness and optical performance, achieving sufficient back focus while maintaining small lens dimensions.
2Reliability
If the light flux is made thicker to reduce dust contamination influence, then the back focus increases, but the lens structure becomes more complex and overall length increases
Solution Approach 1:
The patent achieves thicker effective light flux and increased back focus by optimizing the aspherical shape parameters (r1, r2) and lens thickness (d) within specific ranges, rather than adding structural complexity. This parameter optimization resolves the contradiction by achieving the desired optical path length through geometric design alone.
3Ease of manufacture
If a single lens is used to reduce cost and size, then manufacturing cost and lens size decrease, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific ranges for lens parameters (thickness d: 0.5-2.0mm, refractive index nd: 1.50-1.65, Abbe number νd: 20-40) that balance manufacturing feasibility with optical performance. These parameter specifications allow mass production while maintaining sufficient precision, resolving the contradiction between low cost and manufacturing accuracy.
Solution Approach 2:
The patent employs an aspherical shape for the lens surfaces, which can be manufactured using standard molding techniques while achieving superior optical performance. The aspherical curvature parameters (r1, r2) are designed to be compatible with conventional manufacturing processes, reducing the precision gap between simple single-lens structures and high-performance optics.
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 design provides a compact, high-performance image pickup lens with sufficient back focus, reduced manufacturing errors, and cost-effective mass production, suitable for both 1/10-inch and 1/12-inch devices, and portable terminals.
Implementation Method 1
a single lens arranged in this order from an object side... focusing an image of a subject on a photoelectric converting portion
Implementation Method 2
it is possible to locate an exit pupil farther away from an imaging plane, reduce the angle of incidence of principal ray (i.e., the angle between the principal ray and an optical axis) of flux of light focused on a peripheral portion of the imaging plane
Data Source
AI summary
Disclosed are an image pickup lens which provides a sufficient back focus and can be subjected to a reflow process while offering a capability to be used with either a 1/10-inch-sized or a 1/12-inch-sized solid-state image pickup device, as well as an image pickup apparatus and a portable terminal employing such an image pickup lens. An image pickup lens for focusing an image of a subject on a photoelectric converting portion of a solid-state image pickup device, the image pickup lens comprising an aperture stop and a single lens arranged in this order from an object side, wherein the image pickup lens satisfies the following conditional formulae:0.70 mm<f<1.60 mm (1)0.70<(r1+r2)/(r1−r2)<1.60 (2)wheref: focal length of the image pickup lens (mm);r1: paraxial radius of curvature of an object-side surface of the single lens (mm); andr2: paraxial radius of curvature of an image-side surface of the single lens (mm).