Sheet Feed Device Retard Roller Pressing Force Adjustment
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Solution Overview
Problem
Conventional image forming apparatuses face difficulties in reducing sheet convey failures across various paper types due to inconsistent pressing forces of the retard roller against the feed roller, leading to issues with thin and thick paper feeding.
Innovation Solution
A sheet feeding device with a pressing force change mechanism that includes a rotation shaft, cam member, and movement member to adjust the biasing force of the retard roller, allowing for customizable pressing force based on paper thickness, ensuring reliable sheet conveyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressing force of the retard roller to the feed roller is increased, then thin paper can be fed successfully, but thick paper experiences convey failure
Solution Approach 1:
The pressing force mechanism is made dynamic by introducing a cam member that converts rotational motion into linear displacement. The cam member rotates together with the rotation shaft, and its cam surface profile varies the pressing force applied by the movement member to the retard roller throughout the rotation cycle, enabling adaptation to different paper thicknesses
Solution Approach 2:
The pressing force parameter is changed by adjusting the position of the movement member along the cam surface. By rotating the rotation shaft, the cam member changes the pressing force parameter dynamically, allowing the system to adapt to different paper types (thin vs. thick) and maintain reliable sheet conveyance across various paper conditions
2Reliability
If the pressing force of the retard roller to the feed roller is decreased, then thick paper can be fed successfully, but thin paper experiences convey failure
Solution Approach 1:
The system employs a dynamic pressing force adjustment mechanism where the cam member's rotation creates varying pressing forces. The cam surface geometry is designed to provide higher pressing force for thin paper and lower pressing force for thick paper, making the system adaptable to different paper types while maintaining reliability
Solution Approach 2:
The pressing force parameter is dynamically changed through the cam mechanism. By rotating the rotation shaft, the system adjusts the pressing force parameter to match the requirements of different paper types, ensuring successful conveyance whether handling thin or thick paper
3Device complexity
If a fixed pressing force mechanism is used, then the structure is simple, but sheet convey failure occurs with large number of sheet types
Solution Approach 1:
Instead of a simple fixed pressing force mechanism, the patent introduces a dynamic adjustment mechanism comprising a rotation shaft, cam member, and movement member. This dynamic system allows the pressing force to vary according to paper type, significantly improving sheet convey reliability across diverse paper types while adding controlled complexity to the mechanism
Solution Approach 2:
The patent changes the pressing force parameter from a fixed value to a dynamically adjustable value through the cam mechanism. This parameter change capability enables the system to handle a large number of sheet types reliably, justifying the increased mechanical complexity by achieving universal adaptability
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 mechanism effectively reduces sheet convey failures by dynamically adjusting the pressing force of the retard roller, ensuring successful feeding of both thin and thick paper sheets.
Implementation Method 1
a cam member which is attached to the rotation shaft and which is rotated together with the rotation shaft; and a movement member which is brought into contact with the cam member and moved in the axial direction in conjunction with the rotation of the cam member
Data Source
AI summary
Provided are: a sheet feed device that is capable of suppressing the occurrence of a sheet feeding fault by changing the pressing contact force of a retard roller against a feed roller; and an image formation device equipped with the same. This sheet feed unit (50) is provided with: a pickup roller (29); a feed roller (31); a retard roller (32); a holding member (40) that holds the retard roller (32); a first biasing member (42) that biases the holding member (40); and a pressing contact force changing mechanism (60) that changes the pressing contact force of the retard roller (32) against the feed roller (31). The pressing contact force changing mechanism (60) has: a rotary shaft (61) disposed parallel to the axial direction of the retard roller (32); a cam member (70) that rotates with the rotary shaft (61); and a movable member (80) that contacts the cam member (70), moves in the axial direction in conjunction with the rotation of the cam member (70), and changes the biasing force generated by the first biasing member (42).