Composite Torque Transfer Body and Spline Assembly for Jitter Reduction
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Solution Overview
Problem
The existing gear driven retraction spline mechanism in image forming devices, such as printers, is torsionally weak, leading to fine line jitter and banding on printed pages due to low frequency oscillations, which are not adequately addressed by previous composite gear designs.
Innovation Solution
A composite torque transfer body and spline assembly is introduced, comprising a plastic torque transfer component and a metal spline component with enhanced stiffness, utilizing press-fitting and fastening elements to secure them together, allowing for increased torsional stiffness and improved torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an all-plastic gear driven retraction spline mechanism is used, then the device complexity is reduced and ease of manufacture is improved, but the torsional stiffness is insufficient leading to fine line jitter and banding
Solution Approach 1:
The patent applies composite materials by combining a metal hub assembly with a plastic gear component. The metal hub provides the necessary torsional stiffness to eliminate jitter and banding, while the plastic gear maintains ease of manufacture and low complexity. The composite structure integrates these two materials through mechanical coupling elements (keys, keyways, splines) to achieve both high strength and manufacturing efficiency.
2Strength
If a composite gear design with metal and plastic parts clamped by bolts is used, then the torsional stiffness is improved, but the manufacturing complexity and assembly complexity increase
Solution Approach 1:
The patent segments the composite gear into distinct functional components: a metal hub assembly and a plastic gear component. Each component can be manufactured independently using optimal processes (metal forming for the hub, injection molding for the plastic gear), then assembled through precision-machined mechanical interfaces. This segmentation maintains ease of manufacture while achieving the required torsional stiffness.
Solution Approach 2:
The patent applies local quality by using metal only where high stiffness is needed (the hub and mounting interface), while the gear teeth and peripheral components remain in plastic. This localized material assignment optimizes manufacturing complexity by limiting complex composite fabrication to only the critical stress zones.
3Manufacturing precision
If the natural frequency of the drive system is low, then the manufacturing cost is reduced, but fine line jitter and banding occur on printed pages
Solution Approach 1:
The patent changes the physical parameters of the drive system by introducing a metal hub assembly with higher density and stiffness. This increases the natural frequency of the drive system, moving it away from the excitation frequencies that cause jitter and banding. The parameter change in material properties directly improves print quality by eliminating vibration-induced defects.
Data Source
AI summary
A composite torque transfer body and spline assembly includes a torque transfer component made of a first material and having a central body portion and a peripheral torque transfer portion integrally attached to and extending about the central body portion, a spline component made of a second material different from and having stiffness greater than that of the first material of the torque transfer component and also having an elongated tubular spline portion and a collar portion integrally attached to and extending about and radially outward from an end of the spline portion, and a plurality of elements on the central body portion of the torque transfer component and the collar portion of the spline component providing separate press-fitting and securing of the components to one another such that the components are mated and rotatable together about a central axis.