Scanner Home Positioning via Color Reference Detection
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Solution Overview
Problem
Existing image reading apparatuses face challenges in quickly and accurately positioning the scanning unit at the home position without colliding with the movable area's edges, often requiring dedicated sensors which increase component count and complexity.
Innovation Solution
The apparatus employs a control device that uses a plurality of trial drive operations with different directions or distances, executing a color determination process to position the scanning unit at the home position by selecting appropriate drive operations and varying speed command signals based on moving distances, utilizing reference portions of different colors to determine the unit's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mark detection method is used to position the scanning unit at the home position, then the positioning accuracy is improved, but the component count and system complexity increase due to requiring dedicated sensors
Solution Approach 1:
The patent combines the home position detection function with the existing image sensor used for document scanning. The image sensor serves dual purposes: reading document images and detecting the colored reference portion for home position detection. This eliminates the need for dedicated sensors while maintaining positioning accuracy.
Solution Approach 2:
The image sensor is designed to perform multiple functions: it acts as both the primary document reading sensor and the home position detection sensor. By making the sensor universal, the patent reduces component count while achieving accurate positioning through the color determination process.
2Speed
If the scanning unit moves quickly to the home position, then the positioning speed is improved, but the risk of collision with movable area edges increases
Solution Approach 1:
The patent uses colored reference portions positioned at known locations within the movable area as advance indicators. The scanning unit detects these reference portions before reaching the home position or potential collision zones, allowing the control device to adjust speed and direction in advance to prevent collisions while maintaining fast positioning.
Solution Approach 2:
The system continuously monitors the scanning unit's position by detecting colored reference portions and provides feedback to the control device. Based on this feedback, the control device dynamically adjusts the drive operations to optimize both speed and safety, reducing collision risk while maintaining fast positioning.
3Measurement precision
If multiple trial drive operations are executed to position the scanning unit accurately, then the positioning accuracy is improved, but the time required for positioning increases
Solution Approach 1:
The patent executes a limited number of trial drive operations (first, second, and third trial drive operations) rather than exhaustive searches. Each trial operation moves the scanning unit a predetermined distance in a specific direction based on detected reference portion positions. This partial action approach achieves sufficient positioning accuracy without excessive time consumption.
Solution Approach 2:
The control device dynamically adjusts the drive operations based on real-time detection results. The number, direction, and distance of trial drive operations are adapted according to the positions of detected colored reference portions, optimizing the balance between positioning accuracy and time efficiency for each specific situation.
Data Source
AI summary
A first reference portion has a lower surface of a first color. A second reference portion is adjacent to the first reference portion in a first direction and has a lower surface of a second color. A data processing portion executes a color determination process of determining whether one or more reference pixel data of a reference area in line image data is data of the first color or the second color. A control device sequentially selects a plurality of drive operations from a plurality of trial drive operations and causes the unit drive device to execute the plurality of drive operations, thereby positioning a scanning unit at a home position. When causing the unit drive device to execute the plurality of drive operations, the control device outputs, to the unit drive device, a speed command signal of a different level according to a moving distance of the scanning unit.