Camera Module Lens Groups with Opposite Focal Lengths
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Solution Overview
Problem
Conventional camera modules with multiple lenses face challenges in achieving compact size and efficient autofocus due to increased thickness and energy consumption, as the movement of lens groups required for zoom and autofocus functions becomes exponential, leading to larger device sizes and higher power consumption.
Innovation Solution
An optical system with first and second lens groups having opposite focal lengths, where the effective diameter of the lenses is smaller than the image sensor diagonal, and one lens group is disposed in the optical axis direction, allowing for minimized movement and power consumption while maintaining autofocus functionality across various distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple lenses are included in the optical system to improve image quality and resolution, then optical performance is improved, but the entire optical system increases in size and thickness
Solution Approach 1:
The optical system is divided into two lens groups with opposite focal length signs. The first lens group has positive focal length and the second lens group has negative focal length, allowing each group to contribute differently to image formation while maintaining a compact overall structure. This segmentation enables high-resolution imaging without requiring a single large lens element.
Solution Approach 2:
Instead of using multiple positive focal length lenses in sequence, the patent employs a lens group with negative focal length following a positive focal length lens group. This inverted arrangement (positive then negative) allows for compact design while maintaining optical performance, as the negative lens group can correct aberrations and enable focusing without adding proportional thickness.
2Adaptability or versatility
If the lens or lens group moves to perform autofocus and zoom functions, then focusing and zooming capabilities are achieved, but the movement amount increases exponentially and energy consumption increases
Solution Approach 1:
The patent enables dynamic focusing and zooming by moving the second lens group (with negative focal length) along the optical axis. The movable lens group adjusts its position relative to the first lens group to achieve different focus distances and magnification levels, providing autofocus and zoom functionality through controlled mechanical movement.
Solution Approach 2:
The optical system achieves different focusing states and magnification levels by changing the positional parameter of the second lens group. By varying the distance between the two lens groups, the system can focus on subjects at different distances and achieve zoom effects without requiring exponential movement distances.
3Adaptability or versatility
If the lens or lens group moves to perform autofocus and zoom functions, then focusing and zooming capabilities are achieved, but the device size increases due to required movement space
Solution Approach 1:
Dividing the optical system into two lens groups with opposite focal lengths allows for compact movement mechanisms. The negative focal length lens group can achieve focusing and zooming effects with smaller displacement distances compared to traditional single-group systems, reducing the overall device volume required to accommodate movement.
Solution Approach 2:
The inverted lens group arrangement (positive then negative focal lengths) enables the movable group to achieve greater optical effect per unit of movement. This configuration allows autofocus and zoom functions to be implemented within a smaller physical envelope, reducing the device size while maintaining functionality.
4Measurement precision
If a plurality of imaging lenses with positive or negative refractive power are used to implement high-performance optical system, then image quality is improved, but it becomes difficult to derive excellent optical and aberration characteristics
Solution Approach 1:
The optical system segments the imaging function into two distinct lens groups with opposite focal length signs. This segmentation allows each group to be optimized for specific optical functions: the first group primarily for light gathering and initial focusing, and the second group for aberration correction and fine focusing, simplifying the overall optimization process.
Solution Approach 2:
By using a negative focal length lens group after a positive focal length lens group, the system naturally corrects certain types of optical aberrations. The negative lens group can counterbalance chromatic and spherical aberrations introduced by the positive lens group, achieving excellent optical characteristics without complex multi-element designs.
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 improved optical performance and a slimmer camera module structure by minimizing the movement distance of lens groups, reducing power consumption, and maintaining constant total track length, thus providing a compact and efficient autofocus function for subjects at infinity or near distances.
Implementation Method 1
an optical system according to an embodiment of the invention includes first and second lens groups sequentially arranged along an optical axis from an object side to a sensor direction and including at least one lens, respectively
Data Source
AI summary
An optical system disclosed to an embodiment of the invention includes first and second lens groups sequentially arranged along an optical axis from an object side to a sensor direction and including at least one lens, respectively, and a focal length sign of the first lens group and a focal length sign of the second lens group are opposite to each other and satisfy the following equation: −1.5<f_2/f_1/0 (f_1 is the focal length of the first lens group, and f_2 is the focal length of the second lens group), the effective diameter (clear aperture) of the lenses included in the first and second lens groups is smaller than a diagonal length of the image sensor, and one lens group of the first and second lens groups may be disposed in the optical axis direction.