Paper Feeding Unit with Adjustable Elastic Force for Consistent Paper Feed
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Solution Overview
Problem
Conventional paper feeding units in image forming apparatuses experience variable paper feeding forces due to paper size, leading to inconsistent paper feeding, particularly with smaller paper sizes like A5, resulting in multiple feeding issues.
Innovation Solution
A paper feeding unit with a knock-up plate elastically biased by adjustable elastic members, where guide sides and force adjusting units adjust the elastic force based on paper width, maintaining a constant paper feeding force through lever mechanisms that alter the height and compression of the elastic members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a spring with constant elastic force supports the knock-up plate, then the structure is simple, but the paper feeding force varies with paper size causing multiple feeding
Solution Approach 1:
The patent applies the dynamics principle by making the elastic member adjustable rather than fixed. The elastic member's compression amount can be dynamically changed according to paper size, allowing the paper feeding force to be maintained at an appropriate level regardless of whether A4 or A5 paper is used. This resolves the contradiction by transforming a static structure into a dynamic one that adapts to different conditions.
Solution Approach 2:
The patent applies parameter changes by adjusting the compression amount of the elastic member based on paper size. When A5 paper is detected, the compression amount is reduced compared to A4 paper, thereby maintaining consistent paper feeding force. This directly addresses the reliability issue caused by varying paper sizes while preserving structural simplicity through a straightforward adjustment mechanism.
2Reliability
If the elastic force of the spring is increased to feed smaller paper, then small paper can be fed reliably, but larger paper experiences excessive feeding force causing multiple feeding
Solution Approach 1:
The adjustable elastic member allows the system to dynamically adapt its force output based on paper size. For small paper (A5), the elastic member is compressed less to provide appropriate feeding force without causing multiple feeding. For large paper (A4), the elastic member is compressed more to ensure reliable feeding. This dynamic adjustment eliminates the harmful effect of excessive or insufficient force.
Solution Approach 2:
The patent changes the compression parameter of the elastic member according to paper size. By reducing the compression amount for A5 paper and increasing it for A4 paper, the system maintains optimal paper feeding force across different paper sizes, preventing both multiple feeding and feeding failures.
3Device complexity
If the knock-up plate is elastically supported with constant force, then the mechanism is simple, but the paper feeding force considerably increases for small paper sizes
Solution Approach 1:
The patent transforms the constant force mechanism into a variable force mechanism by making the elastic member adjustable. The compression amount can be changed based on paper size, allowing the paper feeding force to be maintained at an appropriate level. This preserves mechanism simplicity while enabling force control through a straightforward adjustment of the elastic member's compression state.
Solution Approach 2:
The patent applies parameter changes by adjusting the compression amount of the elastic member. For A5 paper, the compression amount is reduced to prevent excessive paper feeding force. For A4 paper, the compression amount is increased to ensure adequate feeding force. This simple parameter adjustment effectively controls the force without complicating the overall mechanism.
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 ensures a consistent paper feeding force across various paper sizes, preventing multiple feeding errors and maintaining stable paper feeding operations by dynamically adjusting the elastic force of the elastic members in response to paper width changes.
Implementation Method 1
at least one elastic member to elastically bias the knock-up plate toward the pickup device
Implementation Method 2
The paper feeding force can be arithmetically derived from a frictional coefficient and a normal force of the pickup roller
Implementation Method 3
force adjusting units adjust the elastic force of the elastic members when the distance between the guide sides is adjusted
Data Source
AI summary
A paper feeding unit and an image forming apparatus having the same capable of maintaining a constant paper feeding force regardless of a size of paper. The image forming apparatus includes a main body, a printing unit provided in the main body to form an image on paper, a paper feeding unit to supply the paper into the main body, and a force adjusting unit. The paper feeding unit includes a paper feeding cassette to load paper therein, a knock-up plate to guide the paper loaded in the paper feeding cassette to a pickup device, an elastic member to elastically bias the knock-up plate toward the pickup device, and guide sides provided at both sides of the knock-up plate. The guide sides are adjusted along a distance therebetween according to a width of the paper. The force adjusting unit adjusts an elastic force of the elastic member when the distance between the guide sides is adjusted according to a size of the paper. Accordingly, since the elastic force of the elastic member supporting the knock-up plate is adjusted through the force adjusting unit which interlocks with the guide sides moving corresponding to the change of the size of the paper loaded on the knock-up plate of the paper feeding cassette, the paper feeding force can be maintained constant all of the time.