Flexible Flat Cable Stress Adjustment for Scanner Lifespan
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Solution Overview
Problem
Conventional image reading devices using flexible flat cables (FFCs) experience a short lifespan due to repetitive bending, which causes stress and eventual disconnection, especially when the FFCs have asymmetrical structures with shielding or impedance adjusting layers.
Innovation Solution
The image reading device incorporates a stress adjusting layer on the FFC to center the transmitting layer in the thickness direction, combined with an elastic sheet member to inhibit reverse bending, and positions the shielding or impedance adjusting layers on the outer side of the U-shaped bend to reduce stress and prevent noise leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the FFC is arranged in a bent manner to connect the scanning unit and housing, then the scanning unit can move reciprocally, but the repetitive reversal of bend direction causes FFC fatigue and disconnection
Solution Approach 1:
The patent applies asymmetry by providing a stress adjusting layer only on one surface of the transmitting layer, creating an asymmetrical FFC structure. This asymmetry positions the neutral axis of bending away from the center of the transmitting layer, reducing tensile stress on the conductors during reciprocating movement and extending FFC life.
Solution Approach 2:
The patent changes the physical parameters of the FFC by adding a stress adjusting layer with specific thickness and material properties. This modifies the bending characteristics and stress distribution within the FFC, allowing it to withstand repetitive bending without fatigue failure.
2Object-affected harmful factors
If the transmitting layer is positioned off-center in the thickness direction to accommodate shielding or impedance adjusting layers, then electromagnetic shielding is improved, but the transmitting layer experiences increased stress during bending
Solution Approach 1:
The patent resolves this contradiction by creating an asymmetrical structure where the stress adjusting layer compensates for the off-center positioning of the transmitting layer. The asymmetrical thickness distribution balances the stress during bending while maintaining the shielding layer configuration for electromagnetic interference protection.
Solution Approach 2:
The patent uses composite material structure by combining the transmitting layer with a stress adjusting layer made of different material properties. This composite structure allows the FFC to simultaneously achieve electromagnetic shielding and stress resistance during reciprocating movement.
3Adaptability or versatility
If the FFC is made flexible to allow reciprocating movement, then the scanning unit can operate, but the repetitive bending reduces the FFC lifespan
Solution Approach 1:
The patent changes the physical parameters of the FFC by adding a stress adjusting layer that modifies the bending stress characteristics. This allows the FFC to maintain flexibility for reciprocating movement while significantly extending its operational lifespan by reducing fatigue.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly extends the lifespan of the FFC by reducing stress during repetitive bending and maintaining signal transmission integrity, achieving a long-life FFC that can handle high-frequency image signals effectively.
Implementation Method 1
the FFC includes a transmitting layer which transmits an electric signal between the scanning unit and the control unit, a shielding layer or an impedance adjusting layer provided on one surface side of the transmitting layer, and a stress adjusting layer provided on a side opposite to the shielding layer or the impedance adjusting layer across the transmitting layer
Implementation Method 2
an elastic sheet member to inhibit reverse bending
Implementation Method 3
a shielding layer or an impedance adjusting layer provided on one surface side of the transmitting layer
Data Source
AI summary
An image reading device which reads an image to obtain an image signal includes: a scanning unit; a chassis member; a control unit provided in a position which does not move together with the scanning unit; and a flexible flat cable which connects the scanning unit to the control unit, includes one end attached to a side of the chassis member and a position other than the one end fixed to a position which does not move with the scanning unit, includes a range closer to the one end than the fixed position parallel to a moving direction of the scanning unit, and is arranged to extend from the one end to one side, be bent into a U-shape, enter between the scanning unit and the chassis member, and reach the fixed position, and the flexible flat cable includes a transmitting layer, a shielding layer, and a stress adjusting layer.