Four-Lens Camera Optics for Thin High-Resolution ToF Modules
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Solution Overview
Problem
Existing camera modules in portable terminals face challenges in achieving high-resolution optical performance while maintaining a small thickness, low power consumption, and light weight, particularly when incorporating a time of flight (ToF) function.
Innovation Solution
An optical system comprising a sequence of lenses with specific focal lengths, refractive indices, and surface configurations, including a first lens with positive power and a fourth lens with negative power, optimized for an F value of 1.7 or less and a TTL/F value ratio of 2.1 to 3, along with a filter tilted to shift light paths for improved depth map extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a camera module with ToF function is embedded in a portable terminal, then depth map acquisition capability is improved, but device size and thickness increase
Solution Approach 1:
The patent combines the imaging lens and ToF lens into a single integrated optical system with four lenses that serves dual functions: capturing visible light images and measuring time of flight for depth map generation. This merging eliminates the need for separate optical paths and reduces overall device volume while maintaining both imaging and depth sensing capabilities.
Solution Approach 2:
The optical system is designed as a multi-functional component where the same four-lens assembly performs both imaging (photoelectric conversion) and ToF measurement (depth detection). The universal design allows a single optical module to replace what would traditionally require separate components, thereby reducing device size and thickness.
2Measurement precision
If high-resolution optical performance is achieved, then image quality is improved, but device thickness increases
Solution Approach 1:
The patent achieves high resolution with reduced thickness by optimizing key optical parameters: setting the F value to 1.7 or less (enlarging aperture relative to focal length), controlling the TTL/F value ratio between 2.1 and 3, and carefully selecting refractive indices and curvature radii for each lens. These parameter changes enable compact form factor while maintaining optical performance.
Solution Approach 2:
The patent employs aspheric surfaces on multiple lens elements (first, third, and fourth lenses) to correct optical aberrations such as spherical aberration and distortion. The aspheric design allows for more compact lens spacing and reduced thickness compared to traditional spherical lenses, while maintaining high imaging quality and resolution.
3Use of energy by moving object
If low power consumption is achieved, then energy efficiency is improved, but optical performance may deteriorate
Solution Approach 1:
The optical system is designed to efficiently utilize ambient light and the projected infrared structured light for both imaging and depth measurement without requiring additional power-intensive components. The integrated design allows the system to self-optimize by using the same optical path for dual functions, reducing redundant power consumption while maintaining performance.
4Weight of moving object
If light weight is achieved, then portability is improved, but manufacturing precision requirements increase
Solution Approach 1:
By merging the imaging and ToF functions into a single four-lens module, the patent reduces the total number of components and assembly steps. The integrated structure inherently improves alignment precision compared to separate modules, as all lenses are positioned relative to a common reference frame, thereby reducing manufacturing complexity despite the lightweight design.
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 enables a compact camera module with high resolution and effective ToF functionality, suitable for low-illuminance environments, by minimizing size and correcting chromatic aberration and distortion.
Implementation Method 1
An optical system includes a first lens, a second lens, a third lens, and a fourth lens that are sequentially arranged from an object side to an image side
Implementation Method 2
a filter tilted to shift light paths for improved depth map extraction
Data Source
AI summary
An optical system according to one embodiment of the present invention includes a first lens, a second lens, a third lens, and a fourth lens, which are sequentially arranged from an object side to an image side, and has an F value of 1.7 or less and a ratio (total top length (TTL)/F value) of a TTL to the F value of 2.1 to 3.