Image Reading Apparatus Command Signal Timing Control
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Solution Overview
Problem
Conventional image reading apparatuses face challenges in maintaining high-quality image data generation due to deviations in the original-reading position caused by differences between the generation period of the command signal and the output time interval of the displacement signal, leading to inefficient correction of transfer timing signals and storage of positional information.
Innovation Solution
An image reading apparatus with a control unit that adjusts the generation timing of the command signal based on the elapsed time since the displacement signal was outputted, ensuring the command signal is generated only when the elapsed time meets a reference value, thereby maintaining an appropriate original-reading position without the need for successive storage of positional information or updating control target values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the command signal is generated periodically with a fixed generation period, then the reading operation can be executed regularly, but the original-reading position deviates from the appropriate position due to velocity variations
Solution Approach 1:
The generation period of the command signal is made variable rather than fixed. The control unit adjusts the generation period dynamically based on the elapsed time from the displacement signal output timing, allowing the reading operation frequency to adapt to velocity variations and maintain accurate original-reading position.
Solution Approach 2:
The control unit uses feedback from the displacement signal timing to adjust the command signal generation timing. By measuring the elapsed time from when the displacement signal is outputted, the system feedback-controls the generation period to ensure the reading unit operates at the correct position despite velocity fluctuations.
2Productivity
If the generation period of the command signal is shorter than the output time interval of the displacement signal, then multiple reading operations can be executed during one displacement interval, but the original-reading position becomes inappropriate
Solution Approach 1:
The system dynamically adjusts the command signal generation timing based on actual displacement signal timing. Even though multiple reading operations may occur during one displacement interval, the generation period is variable-controlled to ensure each reading operation occurs at the appropriate original-reading position.
3Manufacturing precision
If the transfer timing signal is corrected based on encoder signal pulse edge counting, then the original-reading position accuracy can be maintained, but complicated processing such as storage of counting value and updating control target value is required
Solution Approach 1:
The invention extracts the essential timing information directly from the displacement signal output timing without requiring intermediate steps of pulse edge counting and value storage. The control unit simply uses the elapsed time from displacement signal output to determine command signal generation timing, eliminating complex processing while maintaining position accuracy.
Solution Approach 2:
The displacement signal timing itself serves as the reference for adjusting the command signal generation timing. The system uses its own internal timing signals (displacement signal and command signal) in a self-contained manner, eliminating the need for external encoder signal processing and complex control target value updates.
Data Source
AI summary
An image reading apparatus includes: a command unit which generates a command signal periodically; a reading unit which reads an original in accordance with the command signal every time the command signal is generated; a conveying unit which conveys at least one of the reading unit and the original so as to change a relative position between the reading unit and the original; a signal output unit which outputs a displacement signal every time the relative position is changed by a predetermined amount corresponding to a reading interval; and a control unit which controls a generation timing of the command signal by the command unit. A generation period of the command signal is less than an output time interval of the displacement signal.