Carriage Protrusion for Image Reader Light Interference
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Solution Overview
Problem
Image readers face reduced accuracy when reading thick documents due to inadequate closure of the document cover, allowing outside light to enter and interfere with the reading process.
Innovation Solution
The image reader incorporates a carriage with a protruding portion or reflection reduction feature on its bottom surface to minimize outside light incidence and reflection towards the image sensor, and a saw-tooth shaped surface to prevent light from entering and being reflected towards the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the document cover is closed to cover the document table, then outside light entry is prevented and image reading accuracy is improved, but when reading thick documents the document cover cannot be adequately closed causing outside light to enter the reading unit
Solution Approach 1:
The light blocking function is segmented from the document cover to a separate protruding portion on the carriage. This allows the protruding portion to independently block light without being constrained by the document cover closure, enabling both thick document handling and light exclusion.
Solution Approach 2:
The protruding portion acts as an intermediary light-blocking element between the document cover and the reading unit. It provides the light blocking function that the document cover cannot adequately provide when reading thick documents, while maintaining document cover closure capability.
2Measurement precision
If the document cover is closed to prevent outside light entry, then reading accuracy is improved, but the structure becomes more complex and may interfere with thick document placement
Solution Approach 1:
The light blocking protruding portion is merged with the existing carriage structure rather than being a separate component. This integration achieves light blocking functionality without adding significant structural complexity or interfering with document placement.
3Ease of manufacture
If a flat bottom surface on the carriage is used, then manufacturing is simple, but light reflects toward the reading unit reducing reading accuracy
Solution Approach 1:
The bottom surface of the carriage is changed from a flat symmetric surface to an asymmetric saw-tooth shape. This asymmetric geometry causes incident light to reflect away from the reading unit rather than toward it, improving reading accuracy while remaining manufacturable.
Solution Approach 2:
The bottom surface uses a saw-tooth geometric shape instead of a flat plane. The angled surfaces of the saw-tooth structure redirect light at specific angles away from the reading unit, preventing light reflection interference.
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 design effectively reduces outside light interference, enhancing image reading accuracy and enabling better shading correction, particularly when reading thick documents.
Implementation Method 1
the carriage including a protruding portion formed to protrude toward the reading unit... reduce an amount of outside light incident to the reading unit
Implementation Method 2
the carriage including a reflection reduction portion formed on a bottom surface of the carriage that faces a lower surface of the reading unit, so as to reduce an amount of light incident to the bottom surface of the carriage and reflected toward the reading unit
Implementation Method 3
a carriage configured to hold the image sensor and move along a sub-scanning direction perpendicular to the main-scanning direction, the carriage having a surface that faces toward the document table and is formed in a saw-tooth shape to prevent light incident through the document table from being reflected toward the image sensor unit
Data Source
AI summary
An image reader is provided, which includes a housing, a document table, a reading unit disposed between the housing and the document table and configured to read an image of a document sheet on the document table, and a carriage configured to hold the reading unit and move along a moving direction, the carriage including a protruding portion formed to protrude toward the reading unit, on a bottom surface of the carriage that faces a lower surface of the reading unit.