Toner Supply Opening Positioning to Prevent Exposure Slit Contamination
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Solution Overview
Problem
In electrophotographic full-color image forming apparatuses of the tandem type, the small distance between exposure slits increases the likelihood of toner contamination, leading to defective images due to toner adherence and transfer onto the exposure slits, despite existing dust shields and shutters.
Innovation Solution
The image forming apparatus positions toner supply openings outside the exposure slits' scanning direction and employs an air flow generating mechanism to direct fallen toner away from exposure areas, ensuring that toner does not contaminate the exposure slits during the mounting or removal of process cartridges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the exposing apparatus is positioned below the photosensitive drums to reduce apparatus size, then the overall apparatus size is reduced, but toner is more likely to fall and contaminate the exposure slits
Solution Approach 1:
The patent repositions the toner supply opening from a vertical arrangement (above the exposure slit in the conventional manner) to a horizontal arrangement (side-by-side with the exposure slit). This dimensional change in the spatial layout ensures that toner supplied horizontally does not fall vertically onto the exposure slit, thereby preventing contamination while maintaining the compact below-drum apparatus configuration
2Object-affected harmful factors
If a dust shield made of glass plate is provided over the exposure slit to prevent toner accumulation, then toner accumulation is reduced, but the laser beam projection is interfered with by the contaminated glass plate
Solution Approach 1:
The patent removes the dust shield component entirely and instead addresses the contamination problem at its source by repositioning the toner supply opening. This extraction of the problematic dust shield and relocation of the toner supply mechanism eliminates the contamination issue without introducing alternative components that could interfere with the laser beam
3Device complexity
If the toner supply opening is positioned directly above the exposure slit, then the structure is simple, but toner falls and contaminates the exposure slit surface
Solution Approach 1:
The patent changes the spatial arrangement from a vertical stacking configuration (toner supply opening above exposure slit) to a horizontal side-by-side configuration. This dimensional repositioning ensures that toner supplied horizontally cannot fall vertically onto the exposure slit, preventing contamination while maintaining structural simplicity without requiring additional protective components
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 toner contamination of exposure slits, maintaining image quality and extending the service life of the apparatus without requiring complex mechanisms or altering the laser beam projection angle.
Implementation Method 1
employs an air flow generating mechanism to direct fallen toner away from exposure areas
Data Source
AI summary
An image forming apparatus includes a rotatable image bearing member; an exposure unit, disposed below the image bearing member, including a transmitting portion for transmitting a laser beam to which the image bearing member is exposed; a developing unit disposed above the exposure unit for developing, with toner, a electrostatic latent image formed on the image bearing member; and a toner supply opening for supplying toner into the developing unit above the exposure unit, wherein the toner supply opening is in a range, with respect to a rotation axial direction of image bearing member, inside an end of the exposure unit and outside the transmission portion.