Sheet Holder Biasing Mechanism for Accurate Rotation Detection

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Solution Overview

Problem

Existing sheet holders in image forming apparatuses face challenges in accurately determining the size of sheets due to dimensional variations, leading to incorrect detection of sheet positions and sizes, especially when using a D-shaped shaft and D-cut engagement configurations that can result in gaps and unreliable contact states.

Innovation Solution

Incorporating a biasing body, such as a spring, to maintain a consistent contact state between the rotary body and detection target, ensuring accurate rotation angle detection and position grasping, even with gaps between the D-cut face and inner wall flat portion, by applying a biasing force that prevents excessive external forces and damage to the rotational position detector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a D-shaped shaft and D-cut engagement configuration is used between the rotary body and detection target, then the rotational position can be detected, but gaps between the D-cut face and inner wall flat portion cause unreliable contact states and inaccurate detection

Engineering Contradiction:

Improverotation angle detection accuracyVSAvoidcontact state reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The biasing body is pre-installed between the rotary body and detection target to apply a preliminary biasing force that ensures continuous contact. This preliminary action prevents gaps from forming during operation, maintaining reliable contact state and accurate rotation angle detection throughout the device's operational life.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The biasing body acts as a cushioning element that compensates for dimensional variations and manufacturing tolerances beforehand. By continuously applying force to maintain contact, it prevents the harmful effect of gaps from occurring during operation, ensuring stable detection accuracy.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If the rotary body and detection target are pressed together to eliminate gaps, then contact reliability improves, but excessive external forces may damage the rotational position detector

Engineering Contradiction:

Improvecontact state reliabilityVSAvoiddamage risk to rotational position detector

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The biasing body applies a controlled, moderate biasing force that optimizes the contact pressure between the rotary body and detection target. This parameter change ensures sufficient contact reliability for accurate detection while maintaining the force within safe limits to prevent damage to the rotational position detector.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The biasing body serves as a protective cushion that prevents excessive forces from being transmitted to the rotational position detector. By absorbing and distributing the contact forces, it protects the sensitive detector from damage while maintaining reliable contact for accurate measurement.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If dimensional variations in sheets are accommodated by the D-shaped engagement configuration, then adaptability improves, but gaps are created that lead to incorrect detection of sheet positions and sizes

Engineering Contradiction:

Improvesheet size accommodationVSAvoidsheet position and size detection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The biasing body is pre-installed to maintain continuous contact between the rotary body and detection target, preventing gaps from forming when sheets of different sizes are accommodated. This ensures that the rotational position detector consistently accurately detects sheet positions and sizes regardless of dimensional variations.

Inventive Principle:

Principle #10Preliminary action

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

This configuration ensures accurate detection of the rotary body's rotation angle and regulator position, leading to precise sheet size determination, while minimizing the risk of damage to the rotational position detector and maintaining a reliable contact state.

Implementation Method 1

a biasing body that applies a biasing force between the rotary body and the detection target

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11279573B2Sheet holder, sheet feeding device incorporating the sheet holder, and image forming apparatus incorporating the sheet holder

Publication Date: 2022.03.22 RICOH CO LTD

AI summary

A sheet holder includes a regulator, a rotary body, a detection target, a rotational position detector, and a biasing body. The regulator moves in directions to approach and separate from an end portion of a sheet. The rotary body has a contact portion and rotates according to movement of the regulator. The detection target is attached to the rotary body, has a contact target portion, and rotates together with the rotary body by contacting of the contact portion of the rotary body with the contact target portion of the detection target in a rotational direction of the rotary body. The rotational position detector detects a rotational position of the detection target. The biasing body applies a biasing force between the rotary body and the detection target to maintain a contact state of the contact portion of the rotary body and the contact target portion of the detection target.