Movable Sensor Carriage for Edge Detection in Image Forming Apparatus
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately sensing the edge position of a recording medium, particularly in ink-jet systems where high precision is required to prevent ink from soaking through to the rear face, necessitating advanced edge detection mechanisms for double-sided printing.
Innovation Solution
A sensor unit comprising an edge detection sensor, a sensor carriage, and a carriage moving mechanism that supports the sensor in the sheet width direction, allowing it to reciprocate and adjust positions to accurately detect the edge of the recording medium, utilizing a CIS (contact image sensor) to sense the edge position and adjust ink nozzle alignment accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed CIS sensor is used to detect sheet edge position, then the device structure is simple, but the measurement precision deteriorates when sheets of different sizes are processed
Solution Approach 1:
The patent applies the dynamics principle by making the sensor carriage movable along the sheet width direction instead of fixed. The carriage can be positioned at different locations to detect edges of sheets with different sizes, enabling accurate edge detection for both small and large sheets. This dynamic positioning capability resolves the contradiction between measurement precision and device complexity.
2Adaptability or versatility
If the sensor carriage is always positioned at one location, then the device operation is simple, but the adaptability to different sheet sizes deteriorates
Solution Approach 1:
The patent applies preliminary action by automatically positioning the sensor carriage to appropriate locations before edge detection begins. The control unit pre-positions the carriage based on the detected sheet size, so that when detection is needed, the sensor is already in the correct location. This eliminates manual positioning operations while maintaining adaptability to different sheet sizes.
3Adaptability or versatility
If the sensor carriage reciprocates to different positions, then the adaptability to different sheet sizes is improved, but the loss of time increases due to movement
Solution Approach 1:
The patent applies periodic action by making the carriage reciprocate between two extreme positions (first and second positions) rather than moving to arbitrary locations. This limited reciprocating motion reduces the time required compared to continuous positioning, while still enabling detection of edges for sheets of various sizes by selecting the appropriate extreme position.
4Manufacturing precision
If high precision edge detection is implemented, then the printing accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the detection mechanism into a movable sensor carriage and a stationary unit housing. The carriage can be independently positioned and moved, while the housing remains fixed. This segmentation allows the detection function to be separated from the structural support function, achieving high precision edge detection without requiring the entire device to be complex.
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
Enhances printing accuracy by precisely detecting the edge of the recording medium, ensuring high precision in double-sided printing and reducing ink spread, thereby improving the overall quality and reliability of the printing process.
Implementation Method 1
This image forming apparatus senses the position of an end part of a sheet in its width direction based on the difference in the intensity of the light received by the CIS with and without a sheet
Data Source
AI summary
A sensor unit includes an edge detection sensor, a sensor carriage, a unit housing, and a carriage moving mechanism. The edge detection sensor is arranged in a conveying portion for conveying a sheet and senses edge positions at both sides in a sheet width direction perpendicular to a sheet conveying direction. The sensor carriage has a carriage main body in which the edge detection sensor is incorporated, and is reciprocatably supported on the unit housing in the sheet width direction. The carriage moving mechanism makes the sensor carriage reciprocate in the sheet width direction. The sensor carriage is selectively positioned at a first position where it makes contact with a first side face at one end side of the unit housing in the sheet width direction or a second position where it makes contact with a second side face at the other end side in the sheet width direction.