Image Reading Apparatus Position Specification via Target Trajectory
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Solution Overview
Problem
Conventional image reading apparatus experience image degradation due to fluctuations in document conveyance speed, leading to inaccurate specification of interrupted reading positions when the line start signal is synchronized with the encoder signal.
Innovation Solution
An image reading apparatus with a position detecting unit, conveyance control unit, and position specifying unit that uses a target position trajectory to accurately determine the interrupted position, allowing for precise resumption of reading operations without synchronization with the encoder signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the line start signal is synchronized with the encoder signal to accurately specify the interrupted position, then the position specification precision is improved, but image degradation occurs due to speed fluctuations causing encoder signal cycle variations
Solution Approach 1:
The patent introduces a timing signal that is independent of the encoder signal as an intermediary to trigger the line start signal. This timing signal is generated based on a predetermined timing relationship with the conveyance operation start timing, rather than being synchronized with the encoder signal. This mediator decouples the line start signal from speed fluctuations, allowing accurate position specification without image degradation.
2Stability of the object's composition
If the document conveyance speed is maintained at constant speed, then the encoder signal cycle remains stable, but the interrupted position cannot be accurately specified when speed fluctuations occur due to control errors
Solution Approach 1:
The patent establishes a predetermined timing relationship between the conveyance operation start timing and the timing signal generation before actual conveyance begins. This preliminary timing setup allows the system to anticipate and compensate for speed fluctuations, generating the line start signal at the correct timing even when speed variations occur, thereby maintaining both stability and precision.
3Reliability
If the line start signal timing is adjusted to compensate for speed fluctuations, then image quality is improved, but the interrupted position specification becomes inaccurate
Solution Approach 1:
The timing signal serves as an intermediary that independently controls both the line start signal timing and the position specification, rather than directly adjusting one based on the other. This intermediary approach allows the system to maintain accurate position specification while compensating for speed fluctuations, resolving the trade-off between image quality and position precision.
Data Source
AI summary
An image reading apparatus including a reading unit that reads a document as an object to be read in a main scanning direction; a conveyance unit that conveys one of the reading unit and the object to be read as an object to be conveyed in a sub-scanning direction; a detecting unit that detects a position of the object to be conveyed; a control unit that controls conveyance of the object to be conveyed, based on the position of the object to be conveyed and a preset target position trajectory; a specifying unit that specifies, based on the target position trajectory, the position of the object to be conveyed at a time when a period of invalidation or interruption of reading operation by the reading unit is started. The reading operation is invalidated or interrupted when a predetermined interruption condition is satisfied.