Image Forming Apparatus Toner Pattern Registration Error Detection
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately detecting registration errors in the main-scanning direction due to the eccentricity and inconstant-speed rotation of photosensitive drums, leading to incomplete prevention of color registration errors.
Innovation Solution
The apparatus includes a controller that forms first toner patterns as lines in the main-scanning direction and second toner patterns slanting from this direction, ensuring these patterns are arranged on an intermediate transfer medium at intervals equal to the circumferential length of the photoreceptors, allowing for accurate detection of positional errors using a sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If test patterns are formed using conventional image stabilization control, then the apparatus can detect positional errors in the main-scanning direction, but the detection accuracy is degraded due to drum eccentricity and inconstant-speed rotation
Solution Approach 1:
The invention divides the test pattern into multiple independent toner marks instead of using continuous lines. By segmenting the pattern into discrete marks at specific positions (including half-circumferential offset), the system can detect positional errors more accurately despite drum eccentricity. Each toner mark serves as an independent measurement point, allowing the system to overcome the reliability issues caused by non-constant drum rotation speed.
2Device complexity
If only horizontal lines are used for test patterns, then the structure is simple, but the detection accuracy is insufficient due to dependency on drum rotation position
Solution Approach 1:
The invention introduces asymmetric positioning of toner marks at half-circumferential intervals. By placing marks not only at standard positions but also at positions offset by half the drum circumference, the system creates an asymmetric reference framework. This asymmetry compensates for the effects of drum eccentricity and variable rotation speed, significantly improving measurement precision without substantially increasing structural complexity.
Solution Approach 2:
The invention adds a dimensional aspect by incorporating toner marks at half-circumferential offsets in addition to standard positional marks. This creates a two-dimensional distribution of reference marks around the drum circumference. By utilizing this additional dimensional information, the system can detect and compensate for positional errors more accurately, transforming a one-dimensional line-based approach into a multi-dimensional mark-based approach.
Data Source
AI summary
An image forming apparatus including a plurality of photoreceptors; a plurality of developing devices for forming toner patterns on the plurality of photoreceptors; an intermediate transfer medium for receiving the toner patterns transferred from the plurality of photoreceptors; a controller for controlling the plurality of developing devices to form first toner patterns that are lines extending in a main-scanning direction and second toner patterns that are lines slanting from the main-scanning direction on the plurality of photoreceptors such that the first toner pattern and the second toner pattern transferred from the same photoreceptor will be arranged on the intermediate transfer medium at an interval in a sub-scanning direction of a circumferential length of the photoreceptor from which the first toner pattern and the second tone pattern are transferred; and a sensor for detecting the toner patterns transferred onto the intermediate transfer medium.