Single Focal Length Lens System for Automotive Cameras
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing single focal length lens systems face challenges in achieving a wide angle of view, compact size, and maintaining optical characteristics stability across varying temperatures, particularly in automotive camera applications where temperature fluctuations are significant.
Innovation Solution
A single focal length lens system design comprising a first lens unit with negative optical power and a second lens unit with positive optical power, utilizing cemented lens elements made of resin with aspheric surfaces, and specific refractive index temperature coefficients to minimize temperature-induced defocusing, while ensuring a wide diagonal angle of view and compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a wide angle of view is achieved through lens design, then the diagonal angle of view increases to 90° or more, but the lens system size and complexity increase
Solution Approach 1:
The lens system is divided into multiple lens units with specific optical powers (first lens unit with negative power, second lens unit with positive power). Each lens unit contains specific lens elements with defined focal lengths and materials, segmenting the complex wide-angle requirement into manageable functional modules that achieve the 90°+ diagonal angle of view without excessive overall complexity
Solution Approach 2:
The patent employs composite material construction with cemented lens elements combining different glass types (positive and negative optical power elements) and resin materials. This composite approach allows achieving wide angle of view through optimized optical path control using material properties rather than simply increasing lens count and size
2Ease of manufacture
If resin lens elements are used to reduce manufacturing cost, then cost-effectiveness improves, but temperature-induced optical characteristic changes increase
Solution Approach 1:
The patent carefully selects and controls the relative refractive index temperature coefficient parameter for resin lens elements, specifying that |dn/dt|MAX≤2.67×10−5. This parameter control allows using cost-effective resin materials while maintaining temperature stability by choosing resin types and formulations with appropriate thermal-optical properties
Solution Approach 2:
The patent combines resin lens elements with glass lens elements in cemented configurations. The glass elements provide temperature stability reference, while resin elements provide cost advantage and specific optical properties. This composite structure balances manufacturing cost with temperature-induced optical characteristic stability
3Manufacturing precision
If cemented lens elements with aspheric surfaces are used to correct aberrations, then optical performance improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates aspheric surfaces on specific lens elements within the cemented lens units. These aspheric surfaces correct spherical aberration and other optical imperfections, improving overall optical performance. The aspheric profiles are strategically placed where they provide maximum benefit while remaining manufacturable with standard precision molding or grinding techniques
4Volume of moving object
If the lens system is compacted to reduce size, then the overall dimensions decrease, but temperature-induced defocusing increases
Solution Approach 1:
The patent optimizes the focal length ratios of individual lens elements and units (e.g., fG2/f between 1.5-3.5, fLN/f between -3.5 and -0.5) to create a compact configuration. These parameter optimizations ensure that the reduced physical dimensions do not compromise the optical path stability, maintaining resistance to temperature-induced defocusing through balanced optical power distribution in the compact form factor
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 lens system achieves a diagonal angle of view of 90° or more, maintains optical performance across a 20-80°C temperature range, and reduces temperature-induced aberrations, making it suitable for automotive camera applications with improved environmental resistance and cost-effectiveness.
Implementation Method 1
the second lens unit is composed of a cemented lens element, the cemented lens element is obtained by cementing two lens elements made of resin
Implementation Method 2
includes a lens element having negative optical power and a lens element having positive optical power, and has a joint surface which is an aspheric surface
Implementation Method 3
where |dn/dt|MAX is a maximum value of absolute values of relative refractive index temperature coefficients in an atmosphere at 0 to 20° C. with respect to light having a wavelength range of 580 to 640 nm
Data Source
AI summary
A single focal length lens system, in order from an object side to an image side, includes a first lens unit having optical power, an aperture diaphragm, and a second lens unit having positive optical power is provided. The first lens unit, in order from the object side to the image side, includes a first sub-lens unit having negative optical power, and a second sub-lens unit having positive optical power. The single focal length lens system satisfies the following condition: |dn/dt|MAX≤2.67×10−5 (|dn/dt|MAX: a maximum value of absolute values of relative refractive index temperature coefficients in the atmosphere at 0 to 20° C. with respect to light having a wavelength range of 580 to 640 nm, which is calculated for each lens element constituting the second sub-lens unit).