Optical Scanner Unit Positioning via Central Sliders
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Solution Overview
Problem
Existing image reading apparatuses face challenges in accurately determining the position of contact image sensors relative to document reading surfaces, especially due to shallow focal depth and potential misalignment issues when scanning documents in both placed and conveyed modes.
Innovation Solution
The design incorporates a pair of central sliders that are disposed on both sides of the contact image sensor, allowing for accurate positioning and stable scanning by maintaining a certain clearance and enabling smooth movement over varying document surfaces, including those with steps, by attaching to the optical scanner unit and supporting the contact image sensor's carriage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the contact image sensor is pressed against the contact glass through an abutment part to determine position, then the positioning accuracy is improved, but the risk of collision damage increases when documents are heavy or have steps
Solution Approach 1:
The patent introduces a cushioning member (elastic element) between the optical scanner unit and the contact glass that absorbs impact forces before they reach the contact image sensor. This cushioning mechanism prevents collision damage when the scanner encounters heavy documents or documents with steps, while still allowing the abutment part to maintain positioning accuracy through the elastic deformation of the cushioning member.
2Stability of the object's composition
If the optical scanner unit is pressed upward by a pressing member to maintain contact with the contact glass, then the scanning stability is improved, but the device complexity increases due to additional pressing mechanisms
Solution Approach 1:
The patent employs a spring-based pressing member that uses elastic force to maintain continuous contact between the optical scanner unit and the contact glass. The spring acts as a counterbalancing force that automatically adjusts to maintain stable scanning pressure without requiring complex control systems or multiple actuating mechanisms, thereby achieving scanning stability with relatively simple device structure.
3Measurement precision
If the contact image sensor is positioned with high accuracy relative to the contact glass, then the image reading precision is improved, but the ease of manufacture decreases due to tighter tolerances
Solution Approach 1:
The patent designs the optical scanner unit with self-aligning features where the abutment part automatically positions the contact image sensor relative to the contact glass through geometric constraints and elastic deformation. The spring-loaded mechanism allows the sensor to self-adjust to the correct position during assembly, eliminating the need for precise pre-positioning or complex adjustment procedures, thereby achieving high positioning accuracy while simplifying the manufacturing process.
Data Source
AI summary
An image reading apparatus includes a for-still-document contact glass serving as a reading face for a placed document, a for-moving-document contact glass serving as a reading face for a document conveyed by an automatic document feeder, and an optical scanner unit to move in a scanning range of the for-still-document contact glass back and forth in a sub-scanning direction to scan the document. The optical scanner unit moves to a scanning range of the for-moving-document contact glass and scans the document in a static manner when the document is conveyed in an automatic manner, and the optical scanner unit includes a contact image sensor, a carriage that holds the contact image sensor in a movable manner in the sub-scanning direction, and a pair of end sliders arranged on both ends of a plane facing the reading face in a longer-side direction of the optical scanner unit.