Document Reading Device Conveyance Control
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Solution Overview
Problem
In document reading devices with a single drive motor for multiple conveying rollers, maintaining a predetermined document interval is challenging, leading to defective images due to temporary conveyance stops caused by storage medium capacity shortages and operational environmental factors.
Innovation Solution
A controller is implemented to manage the conveyance of document sheets by stopping the conveyance when a read request is not received, ensuring that the image from a second document sheet is invalidated if its trailing edge has not passed through the reading position, and validated once it has, thereby preventing defective image output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single drive motor is used to drive multiple conveying rollers, then device cost is reduced, but it becomes difficult to individually block drive force to each roller, making it hard to maintain predetermined document intervals
Solution Approach 1:
The patent applies dynamics by making the drive force transmission flexible and adjustable. Instead of fixed mechanical connections, the system uses a controller to dynamically control the rotation of each conveying roller independently, even though they are all driven by a single motor. This allows the drive force to be selectively transmitted or blocked to each roller based on real-time needs, enabling precise document interval control without adding complex mechanical transmission components.
Solution Approach 2:
The patent changes the control parameter from mechanical force transmission to electrical motor control. By controlling the rotation speed and timing of each conveying roller through the controller, the system can precisely manage document intervals. The controller adjusts the rotational parameters of each roller independently, allowing flexible control of document conveyance timing and interval without requiring additional mechanical transmission parts like clutches or solenoids.
2Productivity
If conveying rollers are always rotated when drive motor is driven, then continuous document conveyance is achieved, but document sheets may be pulled together and fed simultaneously, making it difficult to maintain proper spacing
Solution Approach 1:
The system dynamically controls the rotation of each conveying roller based on the position and state of document sheets. The controller can independently adjust the rotation timing of each roller, allowing continuous conveyance while preventing multiple sheets from being pulled simultaneously. This dynamic control ensures that sheets are separated and conveyed one by one, maintaining proper spacing throughout the continuous conveyance process.
Solution Approach 2:
The system uses feedback from sensors to detect the position and state of document sheets, and the controller adjusts the rotation of conveying rollers based on this feedback. This closed-loop control ensures that each sheet is properly separated and conveyed at the correct timing, preventing sheets from being pulled together while maintaining continuous operation.
3Reliability
If reading is temporarily stopped due to storage medium capacity shortage, then storage overflow is prevented, but document conveyance speed reduces causing elongated defective images
Solution Approach 1:
The system performs preliminary action by controlling the conveyance speed and timing of document sheets based on the storage medium's capacity status. Before reading begins or during the reading process, the controller can adjust the conveyance speed to match the processing capacity, preventing storage overflow while maintaining proper image quality. This preliminary coordination between conveyance and reading operations avoids the need for abrupt stops that cause defective images.
Solution Approach 2:
The system dynamically adjusts the conveyance speed of document sheets based on real-time storage capacity and reading status. When storage capacity is low, the controller slows down or pauses conveyance temporarily, then resumes at appropriate timing to prevent elongated images. This dynamic speed control ensures that reading operations complete successfully without storage overflow, while maintaining proper image quality by avoiding abrupt conveyance interruptions.
Data Source
AI summary
A document reading device includes a conveyer for conveying a document sheet using a single drive source, a reader for reading an image of the document sheet being conveyed through a reading position, and a controller for stopping the conveyance by the conveyer if a read request for a first document sheet, which is being conveyed upstream of the reading position in a conveyance direction, has not received. The controller invalidates the image read from a second document sheet which is being conveyed downstream of the first document sheet if the trailing edge of the second document sheet has not passed through the reading position at a timing when the conveyance is stopped because of the read request having not been received, and validates the image read from the second document sheet if the trailing edge of the second document sheet has passed through the reading position.