Scanner Carriage Homing Using a White Reference Plate
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Solution Overview
Problem
Existing image reading apparatuses require additional parts, such as single-purpose sensors, to set the carriage at the home position, which increases cost, particularly in low-end models.
Innovation Solution
An image reading apparatus that uses a first white reference plate positioned between the document setting region and the carriage path, along with a controller that moves the carriage based on image data analysis to determine the home position without a single-purpose sensor, by checking for a white reference plate edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single-purpose sensor (such as a photo interrupter) is used to detect the carriage home position, then the carriage positioning accuracy is improved, but the number of parts and cost increase
Solution Approach 1:
The imaging device originally designed for reading document images is made to serve a dual function: it also detects the carriage home position by reading the white reference plate. This eliminates the need for a separate single-purpose sensor while maintaining positioning accuracy. The controller distinguishes between document reading mode and home position detection mode based on the carriage position and operational context.
Solution Approach 2:
The white reference plate, which is already present in the system for imaging calibration purposes, is utilized to provide home position detection functionality. The system uses its own existing components (imaging device and white reference plate) to accomplish the positioning task, rather than adding external dedicated sensors.
2Reliability
If a single-purpose sensor is used to set the carriage at home position, then the positioning reliability is improved, but the manufacturing cost increases
Solution Approach 1:
The imaging device performs both document imaging and home position detection functions. By reusing the existing imaging device and white reference plate, the system avoids additional component costs while maintaining reliable positioning through the same high-precision imaging technology used for document scanning.
Solution Approach 2:
The white reference plate serves as a simple, inexpensive visual marker that can be easily manufactured and replaced if needed. It provides a reliable detection target without requiring complex or expensive sensor components, making the overall system more cost-effective.
3Productivity
If the carriage is positioned using image data analysis of the white reference plate, then the positioning speed is improved, but the measurement complexity increases
Solution Approach 1:
The patent replaces traditional mechanical or electrical sensor-based positioning detection with an optical/image processing approach. The controller analyzes image data from the imaging device to detect the white reference plate's position, substituting physical contact or dedicated sensors with non-contact optical measurement and digital image analysis algorithms.
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
Accurately sets the carriage at the home position without additional sensors, reducing costs and shortening the positioning time, while maintaining precision.
Implementation Method 1
The imaging device reads an image of the document placed on the contact glass, by receiving the light emitted from the light source and reflected
Data Source
AI summary
An image reading apparatus includes a carriage, a drive mechanism, an imaging device, a controller, and a first white reference plate. The controller controls the drive mechanism, thereby moving the carriage to a search start position, located on a side of a document setting region with respect to a region occupied by the first white reference plate, decides, on a basis of image data on an outer side of the document setting region in the main scanning direction, sequentially read by the imaging device while the carriage is being moved in a first direction, from the search start position toward the region occupied by the first white reference plate, whether a read image is white, and positions the carriage at a home position, by moving the carriage from a position thereof when the read image was decided as white, by a predetermined distance in the first direction.