Developing Sleeve Speed Control for Toner Density Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional functional separation type developing devices face issues with locally uneven developer density and unplanned downtime due to immobile developer layers and inefficient developer recovery, particularly during toner layer movement control.
Innovation Solution
The image forming apparatus incorporates a developing device with a partitioned chamber system, featuring a first chamber for developer supply, a second chamber for recovery, and a third chamber for additional developer conveyance, along with independent drive systems for conveying screws and the developing sleeve, allowing for controlled rotational speed ratios to manage developer distribution and prevent overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If toner layer movement control is executed by reducing Vsc/Vs1 ratio during non-image forming periods, then immobile developer layer is collapsed and locally uneven density is prevented, but developer may overflow from the recovery chamber due to insufficient recovery space
Solution Approach 1:
The recovery chamber is divided into a first region where the second conveying screw is arranged and a second region where the third conveying screw is arranged. This segmentation allows different zones of the recovery chamber to handle developer flow differently, with the third conveying screw specifically managing developer movement in the second region to prevent overflow during toner layer movement control.
Solution Approach 2:
The third conveying screw acts as an intermediary mechanism between the developer supply system and the recovery chamber. It specifically controls developer conveyance in the second region of the recovery chamber, mediating the developer flow to prevent overflow while maintaining the benefits of toner layer movement control.
2Ease of operation
If functional separation type developing device is used with separate supply and recovery chambers, then developer supply and recovery functions are independent, but developer distribution becomes uneven with higher concentration at downstream sides of both chambers
Solution Approach 1:
Different regions of the recovery chamber are given different functions through the arrangement of multiple conveying screws. The second conveying screw handles developer conveyance in the first region while the third conveying screw manages the second region, creating local quality differences that counteract the natural accumulation tendency and achieve more uniform developer distribution.
Solution Approach 2:
The system uses multiple conveying screws that can operate independently to dynamically adjust developer distribution. The third conveying screw specifically compensates for the downstream accumulation effect by actively managing developer flow in the second region, making the distribution dynamic rather than static.
3Device complexity
If conventional single chamber developing device is used, then structure is simpler, but immobile developer layer forms on upstream side of regulating blade causing toner charge amount difference and locally uneven density
Solution Approach 1:
The developing device separates the chamber into distinct supply and recovery regions with independent conveying mechanisms. This segmentation prevents the formation of a large immobile developer layer by continuously actively managing developer flow through multiple conveying screws positioned at different locations.
Solution Approach 2:
The multiple conveying screws work continuously to maintain developer movement and prevent stagnation. The third conveying screw in particular ensures continuous developer circulation in the second region of the recovery chamber, eliminating the conditions that lead to immobile layer formation and charge inconsistency.
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 effectively prevents locally uneven developer density and reduces downtime by ensuring stable developer supply and recovery, maintaining optimal developer distribution and preventing overflow during both image forming and non-image forming periods.
Implementation Method 1
a magnet, which has a plurality of magnetic poles and generates a magnetic field for causing the developer to be borne on the surface of the developing device
Implementation Method 2
a first conveying screw arranged in the first chamber and configured to convey the developer in a first direction, a second conveying screw arranged in a first region of the second chamber and configured to convey the developer in a second direction opposite to the first direction
Data Source
AI summary
An image forming apparatus includes an image bearing member, a developing device, first and second drive portions, and a controller. The developing device includes first, second, and third conveying screws, and a developer bearing member. A ratio of a rotational driving speed (Vsc) of the first and second conveying screws by the first drive portion to a rotational driving speed (Vs1) of the developer bearing member by the second drive portion is Vsc/Vs1. A ratio of a rotational driving speed (Vsc3) of the third conveying screw by the second drive portion to the developer bearing member rotational driving speed (Vs1) is Vsc3/Vs1. In a control mode, the controller controls the first and second drive portions so that Vsc/Vs1 in a non-image forming period becomes less than Vsc/Vs1 in an image forming period such that Vsc3/Vs1 in the non-image forming period is equal to Vsc3/Vs1 in the image forming period.