Sheet Feeding Device With Stable Retard Roller Contact
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Solution Overview
Problem
Conventional sheet feeding devices experience unstable push contact force between the retard roller and the feed roller, leading to issues such as double sheet feeding or sheet feed errors due to inconsistent force application.
Innovation Solution
The sheet feeding device incorporates a retaining member supported in a rockable manner with a rocking axis parallel to the retard roller's rotation shaft, utilizing a pushing mechanism with a biasing member to stabilize the contact force by positioning the retard roller at either a retract or push contact position based on the cassette's mounting state, ensuring a 45 degrees or less angle between the pushing direction and the connection line of the rollers' centers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the push contact force of the retard roller against the feed roller is increased to prevent sheet feed errors, then sheet feeding reliability improves, but double sheet feeding occurs
Solution Approach 1:
The retaining member is designed to be movable between a retracted position and a push contact position, allowing the retard roller to dynamically adjust its contact force with the feed roller. This dynamic adjustment enables the system to apply sufficient force to prevent sheet feed errors while avoiding excessive force that would cause double sheet feeding, thereby resolving the contradiction between reliability and harmful effects
Solution Approach 2:
The pushing mechanism changes the contact force parameter by positioning the retaining member at different locations along the feed roller's circumference. By adjusting the pushing position and force, the system optimizes the retard roller's contact pressure to achieve reliable single sheet feeding without causing double sheets to be fed, thus resolving the contradiction
2Object-generated harmful factors
If the push contact force of the retard roller against the feed roller is decreased to avoid double sheet feeding, then harmful effects reduce, but sheet feed errors occur
Solution Approach 1:
The movable retaining member enables dynamic control of contact force, allowing the system to apply just enough force to prevent sheet feed errors without exceeding the threshold that causes double sheet feeding. This dynamic adjustment resolves the contradiction by adapting the force level to the actual feeding conditions
Solution Approach 2:
The pushing mechanism provides feedback control by adjusting the retaining member's position based on the interaction between the retard roller and feed roller. This feedback mechanism ensures that the contact force remains within the optimal range to prevent both sheet feed errors and double sheet feeding, resolving the contradiction between reducing harmful effects and maintaining reliability
3Device complexity
If the pushing member directly pushes the retaining member perpendicular to the roller axis, then the structure is simple, but the push contact force becomes unstable
Solution Approach 1:
The pushing member acts as an intermediary that translates motion into a controlled pushing force on the retaining member. By positioning the pushing member to push at a specific location and angle, it mediates between the simple actuating motion and the stable contact force requirement, resolving the contradiction between structural simplicity and force stability
Solution Approach 2:
The pushing mechanism changes the directional parameters of the pushing force by positioning the pushing member to apply force at an optimized angle and location on the retaining member. This parameter optimization ensures stable transmission of pushing force to the retard roller, resolving the contradiction between simple structure and stable contact force
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
Stabilizes the push contact force between the retard roller and feed roller, preventing double sheet feeding and reducing sheet feed errors by efficiently transmitting the biasing force, thereby enhancing the reliability of the sheet conveyance process.
Implementation Method 1
a first biasing member that biases the pushing member
Data Source
AI summary
A sheet feeding device includes a cassette storage part, a sheet feed cassette, a pickup roller, a feed roller, a retard roller, a retaining member, and a pushing mechanism. The pushing mechanism pushes the retaining member so that the retard roller is pushed to contact with the feed roller. The pushing mechanism includes a pushing member that contacts and pushes the retaining member, and a biasing member that biases the pushing member. In a plane perpendicular to a rotation shaft of the retard roller, a pushing direction of the pushing member in a push contact position against the retaining member forms an angle of 45 degrees or less, with a straight line connecting the center of the rotation shaft of the retard roller and the center of a rotation shaft of the feed roller.