Doctor Member Gap Variation for Developing Sleeve Adherence
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the developing sleeve adherence issue occurs due to high adhesion forces of certain toners, leading to background stains and uneven image density, especially at the ends of the developing sleeve where the pressure is greater, causing the toner to adhere excessively.
Innovation Solution
The developing device incorporates a doctor blade with a regulating portion that maintains a specific distance from the developing sleeve, adjusting the scooping amount and developing gap to keep the adjustment amount below the adherence threshold, preventing excessive toner adherence by shaping the doctor blade to be almost parallel at the ends and convex in the center, and using a linear or grooved design to ensure uniform developer distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the doctor member is disposed with a small doctor gap to the developing roller, then the amount of developer supplied onto the developing roller is reduced, but the developing sleeve adherence occurs due to excessive pressure
Solution Approach 1:
The doctor member is designed with different gap distances at different locations: a first distance (smaller gap) at the center portion and a second distance (larger gap) at the end portions. This local variation in gap distance allows the center to supply sufficient developer while the ends maintain larger gaps to prevent adherence, resolving the contradiction between developer supply and adherence prevention.
Solution Approach 2:
The doctor member is segmented into functionally distinct regions: a center portion for active developer supply and end portions for adherence prevention. This segmentation allows each region to optimize its local function, with the center providing developer and the ends preventing adherence issues.
2Manufacturing precision
If the amount of developer on the developing sleeve is increased to ensure adequate coverage, then the image density is improved, but the developer adheres excessively to the developing sleeve causing background stains
Solution Approach 1:
By creating local quality differences in the doctor member gap distances, the invention ensures adequate developer coverage at the center (improving image density) while preventing excessive developer accumulation at the ends (preventing background stains). This resolves the contradiction between image density and background stain prevention.
3Productivity
If the doctor gap is uniformly small across the entire doctor member, then the developer supply is efficient, but the pressure at the ends causes toner to adhere excessively
Solution Approach 1:
The doctor member implements local quality variation with smaller gap distances at the center for efficient developer supply and larger gap distances at the ends to prevent toner adherence. This resolves the contradiction between overall developer supply efficiency and local adherence prevention at the ends.
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 developing sleeve adherence and ensures stable image quality with reduced background stains by maintaining the adjustment amount below the adherence threshold, even after forming a large number of sheets, and is adaptable to different toner types and environmental conditions.
Implementation Method 1
The developing roller includes a developing sleeve bearing the developer, a magnet roller in the developing sleeve
Data Source
AI summary
A developing device includes a developer container, a developing roller, and a doctor member. The developer container contains a developer including a toner and a developer. The developing roller includes a developing sleeve bearing the developer, a magnet roller in the developing sleeve. The doctor member includes a regulating portion regulating an amount of the developer home on the developing sleeve to be a predetermined amount. The regulating portion is disposed with a first distance from the developing sleeve. The developing sleeve is disposed with a second distance from an image hearer, and when the developing sleeve bearing the predetermined amount of developer passes a vicinity of the image bearer, a value obtained by dividing the predetermined amount by the second distance is less than a threshold of occurrence of adherence of the developer to the developing sleeve.