Flexible Flat Cable Folded-Ridge Design for Low-Friction Scanning
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Solution Overview
Problem
The flexible flat cable (FFC) in image reading devices can come into contact with the document table glass due to the movement of the sensor unit, leading to increased friction, potential entanglement, and operation failures.
Innovation Solution
The FFC is designed with a curved portion that includes a folded ridge facing outward, forming a fold region along the longitudinal direction where the image reading unit and control unit are not electrically coupled, minimizing friction and preventing entanglement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the FFC is used to electrically couple the moving sensor unit and control unit, then electrical connection is maintained, but the cable may come into contact with the document table glass causing friction and entanglement
Solution Approach 1:
The FFC is segmented into a first region with conductors for electrical coupling and a second fold region without conductors that can be folded to reduce friction. This segmentation allows the cable to maintain electrical connection where needed while creating a friction-reducing fold in the region that contacts the document table.
Solution Approach 2:
The FFC incorporates a folded ridge forming a curved structure in the fold region, changing the contact geometry from flat to curved. This curvature allows the cable to roll or glide more smoothly over the document table surface, reducing frictional forces and preventing entanglement during sensor unit movement.
2Object-affected harmful factors
If the FFC is folded to reduce friction, then contact with document table is minimized, but electrical coupling in the fold region is interrupted
Solution Approach 1:
The FFC is divided into functional segments: the first region contains conductors for electrical coupling, while the second fold region deliberately excludes conductors. This segmentation allows the fold region to be optimized for friction reduction without compromising electrical connection integrity in the active region.
Solution Approach 2:
Conductors are extracted from the fold region of the FFC, removing the electrical coupling function from the friction-prone area. This extraction allows the fold region to be dedicated solely to mechanical flexibility and friction reduction, while electrical coupling is maintained in the protected first region.
3Ease of operation
If the sensor unit moves in scanning direction, then document reading is enabled, but the FFC may be caught by the document table glass
Solution Approach 1:
The folded ridge creates a curved, rounded profile in the FFC that contacts the document table. This curved geometry reduces the coefficient of friction compared to a flat cable, allowing the sensor unit to move smoothly during scanning without the cable being caught or snagged on the table surface.
Solution Approach 2:
The physical parameters of the FFC are changed by introducing a folded structure that alters the contact surface properties. This structural modification changes the friction characteristics and mechanical behavior of the cable, enabling reliable operation during sensor unit movement while maintaining electrical connection.
Data Source
AI summary
An image reading device includes: an image reading unit that moves in a scanning direction and thus reads a document; a control unit that controls the image reading unit; and a cable that electrically couples the image reading unit and the control unit to each other, the cable including a curved portion and being folded so that a folded ridge faces outward at the curved portion, in a fold region folded along a longitudinal direction, the image reading unit and the control unit not being electrically coupled in the fold region.