Image Reading Apparatus Interrupted Position Resumption
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Solution Overview
Problem
Conventional image reading apparatus experience image degradation due to interruptions in document reading processes, particularly when the buffer becomes full, and require high-resolution encoders to maintain reading resolution, leading to increased costs and sensitivity to fluctuations in object conveyance speed.
Innovation Solution
An image reading apparatus with a signal output unit that periodically outputs a line start signal, a conveyance unit controlled by a motor to adjust position trajectories, and a position specifying unit to accurately restart reading operations without synchronizing the line start signal with the encoder signal, allowing for precise resumption of reading from the interrupted position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the line start signal is made synchronous with the encoder signal to accurately specify the interrupted position, then the reading resolution can be maintained, but high-resolution encoders are required which increases manufacturing costs
Solution Approach 1:
The patent introduces a position detecting unit that detects the position of the line sensor or document using a different mechanism (such as a lower-resolution encoder combined with trajectory calculation) rather than directly using high-resolution encoder signals synchronized with the line start signal. This intermediary position detection method allows accurate interrupted position specification without requiring expensive high-resolution encoders.
Solution Approach 2:
The patent replaces the direct mechanical coupling between high-resolution encoder and line start signal synchronization with a computational approach. The control unit calculates the interrupted position based on detected position data and trajectory information, substituting the need for mechanically synchronized high-resolution encoding with software-based position tracking.
2Measurement precision
If the line start signal is synchronized with the encoder signal, then the interrupted position can be accurately specified, but image degradation occurs when conveyance speed fluctuates due to control errors
Solution Approach 1:
The patent implements a feedback mechanism where the position detecting unit continuously monitors the actual position of the line sensor or document, and the control unit uses this feedback information to calculate and adjust the interrupted position. This closed-loop feedback system compensates for speed fluctuations and control errors, maintaining image quality stability while accurately specifying the interrupted position.
Solution Approach 2:
The patent performs preliminary position detection and trajectory calculation before the interruption occurs. By continuously tracking position and predicting the intended trajectory, the system can accurately determine where reading should resume even after speed fluctuations or interruptions, preventing image degradation at the restart point.
3Productivity
If constant speed conveyance is used to read the document, then reading efficiency is maintained, but the buffer becomes full when downstream processing is delayed, requiring interruption of reading
Solution Approach 1:
The patent performs preliminary detection of the interrupted position using the position detecting unit before the buffer becomes full. By accurately identifying where reading should resume in advance, the system can quickly restart reading operations without losing efficiency, minimizing the impact of buffer interruptions on overall productivity.
Solution Approach 2:
The patent creates a computational model or copy of the intended reading trajectory and position information. This copied trajectory data allows the system to rapidly recalculate and resume reading from the correct position after buffer interruptions, maintaining reading efficiency without requiring continuous uninterrupted operation.
Data Source
AI summary
The image reading apparatus conveys a reading unit or a document to read the document. Conveyance is implemented by motor control based on a target position trajectory. The reading unit reads the document each time a line start signal is inputted. When a predetermined condition is satisfied, the reading operation is invalidated. A conveyance position at a timing to start the first reading operation invalidated is specified as an interrupted position. The object is arranged at a conveyance restart position moved back from the interrupted position. A target position trajectory is newly set. A conveyance time from the conveyance restart position to the interrupted position defined by the target position trajectory is an integral multiple of an output cycle of the line start signal. The motor control based on the target position trajectory is started at a timing coinciding with an output timing of the line start signal.