Image Reading Device Rear End Detection Streak Reduction
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Solution Overview
Problem
Existing image reading devices struggle to accurately detect the rear end of a sheet, leading to incomplete removal of streaks on non-standard sized sheets, as the behavior of the rear end becomes unstable after passing through a front-side reading roller.
Innovation Solution
An image reading device equipped with a tray, paper feed roller, first and second sensors, scanner, and controller, where the controller determines the time duration for reading the back side of the sheet based on the detection of the front and rear ends, ensuring consistent reading lengths on both sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rear end of the sheet is detected by a sensor after passing through the front-side reading roller, then the streaks on the rear end can be removed by masking, but the detection becomes unreliable because the behavior of the rear end becomes unstable
Solution Approach 1:
The patent applies preliminary action by measuring the sheet length before the rear end passes through the front-side reading roller. The sensor detects the rear end at an earlier position (upstream of the roller), and the controller calculates the reading duration based on this preliminary measurement. This ensures accurate streak removal masking without relying on unstable detection after the sheet passes through the roller.
2Ease of operation
If the reading duration for the back side is determined based on standard sheet sizes, then the reading process is simple, but non-standard sized sheets produce streaks because the reading extends beyond the sheet length
Solution Approach 1:
The patent applies dynamics by making the reading duration variable rather than fixed. The controller dynamically adjusts the reading duration based on the actual sheet length detected by the sensor. For non-standard sheets, the reading duration is extended or reduced accordingly, ensuring the reading stops exactly at the rear end without producing streaks, while maintaining simple operation for standard sheets.
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 enables stable reading of both sides of non-standard sized sheets by accurately determining the reading duration for the back side, reducing streaks and ensuring consistent image quality.
Implementation Method 1
a first sensor that detects a front end and a rear end of the sheet as the sheet is conveyed
Implementation Method 2
a second sensor that detects the front end of the sheet as the sheet is conveyed
Implementation Method 3
read an image on the back side of the sheet at a back-side reading position
Data Source
AI summary
An image reading device includes a tray, a paper feed roller that conveys a sheet, a first sensor that detects a front end and a rear end of the sheet, a second sensor that detects the front end of the sheet, and a scanner that reads an image on a front side of the sheet and reads an image on a back side of the sheet. A controller determines a first time duration that elapses from the detection of the front end of the sheet by the first sensor to the detection of the rear end of the sheet by the first sensor and operates the scanner to read the image on the back side of the sheet over a second time duration equal in length to the first time duration. The second time duration begins after the front end of the sheet is detected by the second sensor.