Image Reading Device Home Position Detection via Optical Boundary
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Solution Overview
Problem
Existing image reading devices face challenges in accurately positioning the reading unit due to increased device size and cost when using sensors, and complications arise from voltage drops causing misalignment, especially when distinguishing a simple home position mark from the document.
Innovation Solution
The implementation of a transparent document table with a frame, a moving mechanism, and a white reference member, where the reading unit includes both a first and second reading part to detect the boundary between the frame and the reference member, allowing the controller to position the unit at a predetermined distance from the boundary, thereby simplifying the positioning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor such as a photo interrupter is used to detect the reading unit position, then positioning accuracy is improved, but device size and cost are increased
Solution Approach 1:
The patent replaces the mechanical sensor-based positioning system with an optical reading system. The reading unit, originally designed to read documents, is utilized to optically detect the mark on the document table, thereby eliminating the need for separate sensors like photo interrupters and reducing device complexity while maintaining positioning accuracy
Solution Approach 2:
The reading unit serves dual purposes: it functions both as the document reading device and as the positioning detection mechanism. By making the reading unit multi-functional, the patent eliminates the need for dedicated positioning sensors, thus reducing device size and cost while achieving accurate positioning
2Device complexity
If a simple mark is used to indicate the home position, then device complexity is reduced, but positioning reliability is worsened due to difficulty in distinguishing from documents
Solution Approach 1:
The patent applies local quality by creating a mark with distinct visual characteristics (different color or pattern) that is localized at the home position. This differentiated local property allows the reading unit to easily distinguish the mark from the document content, ensuring reliable positioning without requiring complex detection algorithms
Solution Approach 2:
The patent utilizes color changes or visual contrast as the key characteristic of the home position mark. By making the mark visually distinct through color or pattern differences, the reading unit can reliably detect the home position by identifying this unique visual feature, thereby improving positioning reliability while keeping the mark simple
3Productivity
If the reading unit stops at a position other than home position due to voltage drop, then productivity is reduced, but using a complicated mark increases detection time
Solution Approach 1:
The patent implements preliminary action by positioning the reading unit at the home position before the reading job begins. The simple, distinct mark allows for rapid detection and positioning, ensuring the reading unit is ready at the correct starting position before document reading commences, thereby maintaining productivity without requiring complex detection algorithms that would increase detection time
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 configuration enables precise and efficient positioning of the reading unit at the home position, reducing the risk of misalignment and complexity, even in the presence of voltage drops or foreign substances, while maintaining a compact and cost-effective design.
Implementation Method 1
a reading unit which irradiates light on a document and introduces the reflected light from the document to a photoelectric conversion element
Implementation Method 2
a reading unit which irradiates light on a document and introduces the reflected light from the document to a photoelectric conversion element
Data Source
AI summary
Then image reading device includes a transparent document table, a frame, a reading unit, a moving mechanism, a white reference member, and a controller. The frame is provided around a peripheral of the document table. The white reference member is provided on the frame adjacent to the document table in the sub scanning direction and has a length in the main scanning direction longer than the document table. The reading unit includes a first reading part which reads an area corresponding to the document table and a second reading part which reads an area corresponding to the frame. The controller detects a boundary between the frame and the reference member based on a read value of the second reading part while moving the reading unit by the moving mechanism, and positions the reading unit at a home position apart from the boundary by a predetermined distance.