Image Scanner Buffer Control for Jammed Document Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses with automatic document feeders, there is a challenge in preventing the output of image data generated from abnormal image signals due to jams, where the jam may not be detected until after some data has already been output.
Innovation Solution
The apparatus includes a conveyance mechanism, a scanner, a buffer memory, and a passage sensor, where the controller determines whether to output image data after a passage prediction time based on the time required for the trailing edge of the document to reach the reading position, preventing the storage of erroneous data in case of a jam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If image data is output immediately after scanning, then productivity is improved, but reliability deteriorates because image data generated from abnormal image signals due to jams may be output before the jam is detected
Solution Approach 1:
The system performs preliminary actions by storing image data in a buffer memory before final output, and calculates passage prediction time in advance based on document length and conveyance speed. This allows the system to prepare for potential jams before they occur, enabling timely detection and prevention of erroneous data output while maintaining continuous processing.
Solution Approach 2:
The system uses feedback from passage sensors that detect document passage at multiple positions. The controller continuously monitors these sensor signals and compares actual document movement against the predicted passage time. When a discrepancy is detected (indicating a jam), the system adjusts its output control to prevent erroneous image data from being output, thus maintaining reliability while preserving productivity.
2Reliability
If passage sensors are positioned upstream of the reading position, then reliability is improved by enabling early jam detection, but loss of time increases because the system must wait for the prediction time to elapse before outputting image data
Solution Approach 1:
The system dynamically adjusts the passage prediction time parameter based on document characteristics (length, conveyance speed) and sensor positions. By calculating the exact time required for a document to travel from the upstream passage sensor to the reading position, the system minimizes the waiting period before image data output while ensuring sufficient time for jam detection. This optimization reduces unnecessary delays while maintaining reliable jam detection.
Data Source
AI summary
According to one embodiment, an image forming apparatus includes a conveyance mechanism, a scanner, a buffer memory, a passage sensor, and a controller. The conveyance mechanism conveys a document along a conveyance path. The scanner reads an image on the document at a reading position along the conveyance path and generates image signals corresponding to the image that is read. The buffer memory stores image data corresponding to the image signals. The passage sensor is on the conveyance path upstream of the reading position. The controller determines whether to output the image data from the buffer memory after a sheet passage prediction time elapses based on the length of time required during a normal operation for the trailing edge of the document to reach the reading position.