Split Line Sensor Placement for Sheet Edge Detection
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Solution Overview
Problem
In image forming apparatuses, the complexity of processing image data from multiple blocks of line sensors increases due to sheet displacement during conveyance, leading to complications in recognizing sheet edges and skew correction, especially when sheet ends fall within or outside block boundaries.
Innovation Solution
The use of split line sensors arrayed along the main scanning direction, placed at non-stretching positions where the distance from one sensor to the ideal edge position exceeds a permissible displacement value, reduces data processing by allowing edge detection with fewer split line sensors and enabling skew correction without stopping the sheet conveyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple blocks of line sensors are used to read the conveyed sheet, then the reading coverage is improved, but the complexity of processing image data increases due to sheet displacement during conveyance
Solution Approach 1:
The line sensor is divided into multiple blocks (first block, second block, third block) arranged in the main scanning direction. Each block independently reads image data from different regions of the conveyed sheet, enabling comprehensive coverage while maintaining simplified processing within each block.
Solution Approach 2:
A registrationless unit is introduced as an intermediary component between the line sensor and the image forming part. This unit corrects sheet displacement and skew during conveyance, allowing each sensor block to process data independently without complex inter-block coordination, thus reducing overall data processing complexity.
2Measurement precision
If multiple blocks of line sensors are used, then the reading capability is enhanced, but the difficulty of recognizing sheet edges and performing skew correction increases
Solution Approach 1:
The line sensor is segmented into multiple blocks with dedicated functions: the first block reads the sheet edge position, the second block reads the main body, and the third block assists with skew detection. This segmentation allows each block to focus on specific measurement tasks, simplifying edge recognition and skew correction.
Solution Approach 2:
The system uses feedback from the first block's sheet edge position reading to adjust the reading positions of subsequent blocks. This feedback mechanism enables dynamic adaptation to sheet displacement, improving edge recognition accuracy while maintaining manageable processing complexity.
3Productivity
If the line sensor reads the conveyed sheet during motion, then productivity is improved, but sheet displacement causes alignment errors beyond permissible limits
Solution Approach 1:
The registrationless unit acts as a mediator that compensates for sheet displacement during conveyance. It adjusts the relative positioning between the moving sheet and the line sensor, ensuring that reading precision remains within permissible limits while maintaining continuous conveyance for productivity.
Solution Approach 2:
The system dynamically adjusts reading parameters based on detected sheet displacement. By changing the reading positions of sensor blocks in response to measured displacement, the system maintains alignment precision within permissible limits while continuing the conveyance process.
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 solution simplifies edge position recognition and skew correction by reducing the amount of data processing required and maintaining sheet alignment within permissible displacement limits, ensuring accurate image formation and conveyance.
Implementation Method 1
The sheet reading unit includes a lamp and a line sensor. The lamp throws light to the conveyed sheet.
Implementation Method 2
The line sensor reads the conveyed sheet. The line sensor includes a plurality of split line sensors. Light-receiving elements of each of the split line sensors are arrayed along a main scanning direction.
Data Source
AI summary
The image forming apparatus includes a sheet conveyance part, an image forming part, and a sheet reading unit. The sheet reading unit includes a line sensor. The line sensor includes split line sensors. The line sensor reads a conveyed sheet. The line sensor includes a plurality of split line sensors. The split line sensors are placed at non-stretching positions, respectively. Each non-stretching position is such a position that as in the main scanning direction, a main-scanning-direction distance from a gap between one split line sensor and another split line sensor to an ideal edge position of every usable regular size exceeds a permissible value.