Photosensitive Drum Exposure Control to Limit Toner Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image forming apparatuses struggle to adjust toner amount on the photosensitive drum accurately when switching between different rotational speeds, leading to excessive toner adhesion in low-speed modes.
Innovation Solution
The apparatus employs a control unit to manage the rotational speed and light emission of light-emitting units, adjusting the light emission timing and intensity to maintain consistent toner application across varying drum speeds by implementing specific control modes and coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the photosensitive drum rotational speed is reduced to convey sheets at lower speed, then sheet conveyance speed is reduced, but the amount of emitted light increases causing excessive toner adhesion
Solution Approach 1:
The patent applies parameter changes by adjusting the light emission parameters (emission amount, emission timing cycle, and number of emitting rows) based on the photosensitive drum rotational speed. When the drum rotates at a lower speed, the control unit increases the light emission timing cycle and/or reduces the number of light-emitting rows to compensate for the increased light accumulation time, thereby maintaining appropriate toner adhesion levels despite the speed reduction.
2Adaptability or versatility
If the light emission timing cycle is extended to match slower drum rotation, then rotational speed adaptation is improved, but exposure amount control becomes insufficient leading to excessive toner
Solution Approach 1:
The patent implements dynamics by making the light emission parameters variable rather than fixed. The control unit dynamically adjusts the light emission timing cycle, emission amount, and number of active light-emitting rows based on the detected photosensitive drum rotational speed. This dynamic adjustment ensures that exposure amount control precision is maintained across different rotational speeds, preventing both insufficient and excessive toner adhesion.
3Quantity of substance
If all light-emitting units emit light continuously, then exposure coverage is maximized, but toner amount cannot be adjusted for different rotational speeds
Solution Approach 1:
The patent applies segmentation by dividing the light-emitting units into multiple rows and selectively controlling which rows emit light based on the rotational speed. The control unit can reduce the number of light-emitting rows that are actively emitting light when the drum rotates slower, thereby reducing total exposure coverage proportionally. This segmented control enables toner amount adjustability while maintaining adequate exposure coverage through the remaining active rows.
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 approach ensures precise toner adjustment and uniform image quality across different conveyance speeds, preventing excessive toner adhesion and enhancing image stability.
Implementation Method 1
an exposure head including a plurality of light-emitting units that emit light on a basis of an image data signal for exposure of the photosensitive drum
Implementation Method 2
a photosensitive drum that rotates about a rotation axis direction
Implementation Method 3
The toner image transferred to a sheet is heated by a fixing unit to fix the toner image to the sheet and form an image
Data Source
AI summary
An image forming apparatus comprises a photosensitive drum, an exposure head and a control unit. The control unit can execute a first mode and a second mode in which the drum is rotated at a second rotational speed that is a/b times of the first rotational speed of the first mode. In exposure of the second mode, the control unit controls a cycle of a light emission timing at a cycle of b/a times of a cycle of the first mode, controls the light-emitting units to cause, among n rows, the light-emitting units of (n×((d−c)/d)) rows to not emit light, and sets a drive current so that an amount of light matches (a×d)/(b×c) times of the first mode.