Image Reading Apparatus Noise Detection via Platen Oscillation
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Solution Overview
Problem
Conventional image reading apparatuses struggle to accurately detect noise caused by dust on the platen, often leading to erroneous detection of patterns in the original image.
Innovation Solution
An image reading apparatus with multiple line sensors arranged in the sub scanning direction and a movable platen, where the platen moves at a different rate relative to the sensors, allowing for precise detection of noise pixels and prediction of noise length based on the order of detection and sensor arrangement, thereby improving noise detection precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pattern-matching is used to detect noise waveform, then noise detection capability is improved, but false detection of actual patterns increases
Solution Approach 1:
The platen is oscillated during the reading process, creating dynamic movement between the dust particles and the line sensor. This oscillation causes dust-generated noise to manifest as characteristic waveforms that differ from static patterns in the original, enabling reliable differentiation between noise and actual image content through temporal dynamics
Solution Approach 2:
The platen oscillation employs periodic motion at a specific frequency and amplitude. This periodic action creates repeating noise waveforms with identifiable characteristics that can be distinguished from non-periodic or differently-periodic patterns in the original image, improving noise detection reliability
2Device complexity
If a single line sensor is used, then device complexity is reduced, but noise detection precision is insufficient
Solution Approach 1:
The detection system is segmented into multiple line sensors positioned at different locations. Each sensor detects noise independently, and the results are combined to improve overall detection precision. The segmentation allows for spatial distribution of detection functions while maintaining manageable complexity
Solution Approach 2:
Multiple line sensors are merged into a unified detection system where their outputs are processed together. The combination of detection results from multiple sensors enhances noise detection precision by providing redundant information and enabling cross-validation of detected noise patterns
Data Source
AI summary
An image reading apparatus includes, with the purpose of detecting noise in an image due to dust on a platen, three line sensors, a platen between an original and the line sensors, a moving mechanism for moving the platen, a noise detection processor detecting noise pixels from multiple data output from the line sensors, an order determination unit determining the order in which the noise pixel is detected, based on the order in which the line sensors are arranged and the direction in which the platen is moved, and a noise length calculator predicting the noise length in the sub scanning direction based on the number of noise pixels successive in the main scanning direction, the original transport rate, the platen moving rate, and the distance between the line sensors.