Document Transport Routing via Length Detection
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Solution Overview
Problem
Existing image reading apparatuses struggle to accurately detect the length of documents in transport direction, especially when multi-feed occurs, leading to improper routing and potential paper jams.
Innovation Solution
The apparatus employs a controller that calculates the length of the document based on detection time points from leading and trailing edge detectors and a multi-feed sensor, switching the transport route accordingly between curved and linear paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thickness sensor is used to detect document thickness and route accordingly, then thick documents can be routed to linear transport route, but the document length detection remains inaccurate especially during multi-feed conditions
Solution Approach 1:
The patent segments the detection process into three distinct detection points: leading edge detector, trailing edge detector, and multi-feed detector positioned at different locations along the transport route. This segmentation allows the system to detect document characteristics at multiple stages, enabling accurate length measurement even during multi-feed conditions by identifying the specific detection time points of each sensor.
Solution Approach 2:
The system uses feedback from multiple detectors to continuously monitor and determine document length. The controller receives signals from the leading edge detector, trailing edge detector, and multi-feed detector, and uses the detection time points feedback to calculate document length dynamically, adjusting the routing decision based on real-time detection results.
2Measurement precision
If multiple detectors are added to improve document length detection accuracy, then detection precision improves, but device complexity and production costs increase
Solution Approach 1:
The patent makes the detectors serve multiple functions: the leading edge detector identifies document start, the trailing edge detector identifies document end, and the multi-feed detector identifies abnormal conditions. Each detector is positioned to provide specific information needed for length calculation, allowing the system to handle both normal single-document transport and abnormal multi-feed conditions using the same detection infrastructure.
Solution Approach 2:
The system changes the parameter being measured from document thickness (in previous systems) to document length. This parameter change is achieved by using the time points when detectors are triggered during transport, converting spatial detection into temporal measurement, which enables accurate length determination without adding complex mechanical measurement devices.
Data Source
AI summary
An image reading apparatus includes a document tray, a common transport route, a curved transport route, a linear transport route, a switching device, a document transport device, a first image sensor, a second image sensor, a trailing edge detector, a multi feed detector, a leading edge detector, and a controller. The controller determines a length of the document in the transport direction, on a basis of a time point that the leading edge detector has detected the leading edge of the document, a time point that the trailing edge detector has detected the trailing edge of the document, and a time point that a detection status of the multi feed detector has been switched to a non-detection state, and guides the document to the curved transport route or the linear transport route from the common transport route, according to the length of the document, by controlling the switching device.