Scanner Pushing Member Gap Design for Thin Document Transport
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Solution Overview
Problem
Existing image reading apparatuses face challenges in maintaining low transport resistance and high reading accuracy, especially when handling thin documents, due to high transport resistance caused by pushing members pressing against transparent members, which can lead to poor document transport and reduced image reading accuracy.
Innovation Solution
The image reading apparatus incorporates a pushing member with a contact portion that comes into contact with the transparent member downstream of the reading region and a gap forming surface upstream, allowing the medium to be transported between the pushing member and the transparent member, while the pressing position is shifted from the contact portion, reducing transport resistance and ensuring accurate image reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressing member presses the pushing member from above a contact position between the pushing member and the transparent member, then the pushing member is pressed toward the transparent member to improve contact, but the transport resistance becomes high and transport becomes poor
Solution Approach 1:
The pressing position is extracted from the contact position between the pushing member and transparent member. The pressing member presses the pushing member at a position shifted in the medium transporting direction, separating the pressing function from the contact function to reduce transport resistance while maintaining reliable contact.
Solution Approach 2:
The pressing position is shifted along the medium transporting direction (longitudinal dimension) rather than pressing directly at the contact point. This dimensional shift allows the pushing member to be pressed toward the transparent member while maintaining a gap at the contact portion, reducing friction and transport resistance.
2Measurement precision
If the pushing member is pressed toward the transparent member to improve reading accuracy, then contact is improved, but transport resistance increases and reading accuracy decreases
Solution Approach 1:
The pressing function is separated from the contact function by shifting the pressing position in the medium transporting direction. This allows the pushing member to maintain reliable contact with the transparent member for accurate reading while the pressing force is applied at a different location, preventing excessive transport resistance.
Solution Approach 2:
Different portions of the pushing member have different functions: the contact portion maintains contact with the transparent member for reading accuracy, while the pressing position (shifted in the transporting direction) applies force to push the medium. This local differentiation of function resolves the contradiction between contact quality and transport resistance.
Data Source
AI summary
A scanner unit includes a first reading section that reads a medium via a transparent member; and a bracing member that pushes the medium toward the transparent member by a coil spring. The bracing member includes a contact portion coming into contact with the transparent member in a downstream of a first reading region, and a gap forming surface that is positioned in a direction further away from the transparent member than the contact portion, which includes the first reading region, in an upstream of the contact portion, and is formed with a gap in which the medium is configured to be transported between the pushing member and the transparent member. A pressing position of the pushing member by the coil spring is shifted from a position of the contact portion in a medium transporting direction.