Partially Toothless Gear Cam Drive for Smooth Pick Arm Meshing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional driving force transmission devices using partially toothless gears in image forming apparatuses experience torque variation issues due to elastic forces from springs, leading to potential clogging and striking sounds during pick arm operations.

Innovation Solution

A driving force transmission device with a drive gear, a driven gear having both toothed and toothless portions, and cam members that manage elastic forces through specific cam surfaces to limit or assist rotation, reducing torque variation without additional components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a feeding spring is used to urge the pick arm during descent, then the pick arm can be driven from the retreating position to the feeding position, but torque variation occurs due to elastic force release causing backlash clogging and striking sounds

Engineering Contradiction:

Improvepick arm descent operationVSAvoidgear meshing smoothness

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The cancel cam surface is designed to generate an elastic force from the first elastic member that opposes and cancels the elastic force release from the second elastic member during pick arm descent. This preliminary anti-action prevents torque variation before it can cause backlash clogging or striking sounds in the gear meshing.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The invention converts the harmful elastic force release from the second elastic member into a beneficial effect by using the cancel cam surface to trigger the first elastic member. The first elastic member's elastic force, originally potentially harmful as torque variation, is now harnessed to counteract the second elastic member's elastic force, transforming the problem into a solution that ensures smooth gear meshing.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Extent of automation

If the cam rotates in conjunction with the trigger cam, then the pick arm can be controlled for rotational motion, but torque variation from spring elastic forces causes inverse input torque affecting cam rotation stability

Engineering Contradiction:

Improvepick arm rotational controlVSAvoidcam rotation stability

Core Design Contradiction:

Extent of automationVSStability of the object's composition

Solution Approach 1:

The first elastic member acts as a counterweight system, providing an opposing elastic force through the cancel cam surface that balances the torque variation caused by the second elastic member. This counterbalancing mechanism stabilizes the cam rotation by neutralizing the inverse input torque that would otherwise disrupt the synchronized rotation between the cam and trigger cam.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Adaptability or versatility

If a partially toothless gear is used to transmit driving force, then the gear can engage and disengage smoothly, but torque variation causes backlash clogging when the gear meshes with the connection gear

Engineering Contradiction:

Improvegear engagement flexibilityVSAvoidbacklash freedom

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The cancel cam surface generates the elastic force from the first elastic member in advance to counteract the torque variation before it reaches the partially toothless gear. This preliminary anti-action ensures that when the gear engages and disengages, the backlash remains free and smooth without clogging, maintaining both engagement flexibility and reliability.

Inventive Principle:

Principle #9Preliminary anti-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

The solution effectively reduces torque variation and prevents clogging and striking sounds by managing elastic forces, enhancing the accuracy and reliability of the pick arm operations in image forming apparatuses.

Implementation Method 1

a first elastic member configured to apply an urging force to the first cam member

Methodology Applied

Scientific EffectElastic force: Elasticity

Implementation Method 2

a follower member configured to be urged by a second elastic member and be moved by the second cam member

Methodology Applied

Scientific EffectElastic force: Elasticity

Data Source

PatentUS11834292B2Driving force transmission device and image forming apparatus

Publication Date: 2023.12.05 CANON KK

AI summary

A driving force transmission device includes a drive gear, a driven gear, which includes a gear portion and a partially toothless gear portion, rotates by the gear portion meshing with the drive gear, stops rotating in response to the partially toothless gear portion facing the drive gear, a first cam member and a second cam member which operate in conjunction with the driven gear, a first elastic member for urging the first cam member, a follower member to which urging force is applied by a second elastic member and which is moved by the second cam member, and a contact portion for coming into contact with the first cam member by urging force of the first elastic member. The first cam member includes a home cam surface for coming into contact with the contact portion so that rotation of the driven gear is limited.