Rib-Structured Agitating Screw for Toner Density Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses, the accumulation of developer at the detection surface of the density detection unit leads to erroneous toner density detection, especially when the fluidity of the developer is reduced, causing image defects like fogging, and existing solutions such as magnetic plates on agitating members can introduce errors and increase costs.
Innovation Solution
A developing apparatus with a conveyance portion featuring a shaft and a conveying blade, along with a projected agitating portion that overlaps with the detection surface, effectively removes developer accumulation by positioning the projected portion upstream in the rotation direction, ensuring accurate toner density detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plate-like agitating member is disposed at the conveyance screw to stabilize developer conveyance, then developer conveyance stability is improved, but developer accumulation occurs at the detection surface causing erroneous detection
Solution Approach 1:
The agitating member is segmented into multiple rib portions (first rib, second rib, third rib) arranged at different angular positions. This segmentation allows different ribs to perform different functions: some ribs agitate the developer while others create gaps to prevent accumulation at the detection surface, resolving the contradiction between conveyance stability and detection accuracy.
Solution Approach 2:
Different portions of the agitating member have different structural characteristics. The rib portions have specific heights and spacing configurations that create localized gaps at the detection surface position. This local quality variation ensures that agitation is provided where needed while preventing accumulation at the detection area, simultaneously achieving conveyance stability and detection accuracy.
2Volume of moving object
If the density detection unit is disposed below the developer container to downsize the apparatus, then apparatus size is reduced, but developer accumulation on the detection surface increases causing erroneous detection
Solution Approach 1:
The rib portions of the agitating member are configured to proactively prevent developer accumulation before it occurs at the detection surface. By creating gaps and maintaining developer flow in advance, the system prevents the harmful effect of accumulation even when the detection unit is positioned below the container, thus maintaining detection accuracy in a compact configuration.
3Reliability
If a magnetic plate is provided on the agitating member to remove developer accumulation, then developer accumulation is removed, but detection accuracy deteriorates due to magnetic plate interference and costs increase
Solution Approach 1:
The invention extracts the harmful magnetic plate component from the system and replaces it with a simple rib-structured agitating member made of non-magnetic material. The rib portions mechanically create gaps and agitate the developer to prevent accumulation, achieving the same accumulation removal function without the detrimental side effects of magnetic interference with the detection unit, thus maintaining detection accuracy and reducing costs.
Data Source
AI summary
A developing apparatus includes a developer bearing member configured to bear and convey a developer containing toner and carrier, a first conveyance screw arranged in a first chamber to convey the developer, a second conveyance screw arranged in the second chamber to convey the developer, and a permeability sensor configured to detect a permeability of the developer. A detection portion of the sensor is arranged below a rotational axis of the second conveyance screw, and a rib portion is formed so as to protrude in a radial direction from a rotation shaft of the second conveyance screw for supplying the developer toward the detection portion.