Variable Mount Elements for Camera Lens FFL Compensation
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Solution Overview
Problem
The challenge in manufacturing integrated camera optics for electronic devices, such as mobile phones, is the high rejection rate of lens modules due to variable flange focal lengths (FFL) caused by fabrication tolerances, leading to issues with image sharpness and increased assembly costs from focusing steps.
Innovation Solution
A method involving the replication of lens modules on a wafer scale using molding or embossing, followed by determining individual focusing parameter values and using mount elements with variable section lengths to adjust the distance between the lens modules and image sensor planes, ensuring the focal plane aligns with the image sensor plane, thereby reducing rejects and eliminating the need for additional focusing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lens modules are manufactured on a wafer scale with fixed focus, then manufacturing efficiency is improved, but fabrication tolerances cause variable FFL values leading to high rejection rates
Solution Approach 1:
The patent applies preliminary action by pre-determining the FFL value of each lens module during wafer-scale manufacturing and pre-selecting mount elements with corresponding compensation values before final assembly. This advance preparation eliminates the need for post-assembly focusing adjustments and ensures that each lens module is paired with the appropriate mount element to achieve the target FFL, thereby maintaining high manufacturing efficiency while achieving precise FFL control.
Solution Approach 2:
The patent changes the parameter of the mount element (specifically the mount section length) to compensate for variations in lens module FFL values. By varying the mount section length parameter across different mount elements, the system can offset the harmful FFL variations caused by fabrication tolerances, transforming the fixed-focus limitation into a compensated system that achieves consistent focusing across all lens modules.
2Manufacturing precision
If additional focusing steps are performed after assembly, then image sharpness is improved, but assembly costs and device complexity increase
Solution Approach 1:
The patent extracts the focusing adjustment function from the final assembly process and integrates it into the mount element design itself. Instead of performing separate focusing steps after assembly, the focusing compensation is built into the mount element's structure (via variable mount section lengths), eliminating the need for additional focusing operations and reducing assembly complexity while maintaining image sharpness.
Solution Approach 2:
The mount element performs the focusing compensation function automatically based on the pre-determined FFL value of the lens module. The system is designed so that the combination of lens module and corresponding mount element self-adjusts to achieve the correct focus, eliminating the need for external focusing adjustments or additional focusing steps during assembly.
3Ease of manufacture
If mount elements with fixed separation distance are used, then assembly is simplified, but FFL variations cause misalignment between focal plane and image sensor plane
Solution Approach 1:
The patent applies local quality by making the mount section length of mount elements location-specific and value-specific rather than uniform. Different mount elements have different mount section lengths tailored to compensate for the specific FFL characteristics of their corresponding lens modules. This localized customization of the mount element geometry maintains assembly simplicity while achieving precise focal plane alignment for each lens module.
Data Source
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AI summary
The invention concerns a method of manufacturing a plurality of optical devices (20a) for cameras, each optical device (20a) having a fix focus lens module (2a) for assembling with an image sensor comprising an image sensor plane (5), each fix focus lens module (2a) comprising one or more lenses (17a, 18a) or lens parts, the method comprises the steps of: ° manufacturing a plurality of lens modules (2a..d); ° determining a lens module value for each lens module (2a.. d), wherein the lens module value is in relationship with the flange focus length FFL (6a..d) of the corresponding lens module (2a..d); ° providing and allocating mount elements (3a..b) to the lens modules (2a.. b, whereas the mount elements (3a..b) are to be arranged within the optical devices (20a) to define a fixed separation distance (6a..b) between the lens modules (2a..b) and the image sensor plane (5), the mount elements (3a..b) having variable mount FFL sections (7a..b) by means of which the geometrical distance (6a) between the lens module (2a) and the image sensor plane (5) is adjusted for each lens module (2a..d) individually or in groups dependent on the optical properties of the lens modules (2a..b), to compensate the variation of the lens module values between the plurality of lens modules (2a.. d), so that the focal planes of the lens modules falls into the image sensor plane (5); ° assembling the lens modules (2a) and the mount elements (2a) to form optical devices (20a).