Arc-Shaped Sliding Portions for Vibration-Free Optical Unit Scanning

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Solution Overview

Problem

Image reading devices with sliding optical units experience vibration and reduced accuracy due to tolerated dimensional errors between circular or oval rail portions and semi-circular or semi-oval sliding portions, leading to rattling issues during sub scanning.

Innovation Solution

An image reading device with a rail portion formed of sheet metal, featuring sliding portions with a substantially arc-shaped cross section and gripping portions that contact the rail portion at two points, preventing rattling and maintaining precise alignment during sub scanning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a circular or oval shaft with a semi-circular or semi-oval bearing recess is used, then the structure is simple and easy to manufacture, but dimensional errors cause rattling and vibration during sub scanning

Engineering Contradiction:

Improveease of manufactureVSAvoidreliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The bearing recess is designed with a spherical surface that matches the curvature of the shaft. This curved interface allows the bearing recess to accommodate dimensional errors and misalignments through its spherical geometry, preventing rattling and vibration while maintaining manufacturing simplicity.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The bearing recess parameters are specifically designed with a spherical surface and appropriate dimensions to compensate for manufacturing tolerances. By optimizing the curvature radius and contact area, the design maintains reliability despite dimensional errors in the shaft or bearing recess.

Inventive Principle:

Principle #35Parameter changes

2Strength

If a square-cornered U-shaped sliding portion is used to contact a circular shaft on three surfaces, then the contact area is increased, but dimensional errors still cause rattling and vibration

Engineering Contradiction:

ImprovestrengthVSAvoidreliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The sliding portion uses a spherical bearing recess instead of a square-cornered U-shape. This curved design maintains contact strength while eliminating the rattling problem by allowing the spherical surface to adapt to dimensional variations, ensuring smooth operation during sub scanning.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Adaptability or versatility

If the optical unit is moved in the sub scanning direction for fixed-document method, then document reading is enabled, but vibration and reduced accuracy occur due to rattling

Engineering Contradiction:

ImproveadaptabilityVSAvoidmeasurement precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The spherical bearing recess design eliminates rattling and vibration during optical unit movement. By providing a smooth, adaptive contact interface that accommodates dimensional errors, the spherical geometry ensures stable operation throughout the sub scanning motion, maintaining measurement precision for document reading.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS8928958B2Image reading device including an optical unit for reading a document image, image forming apparatus therewith, and optical unit for reading a document image

Publication Date: 2015.01.06 KYOCERA DOCUMENT SOLUTIONS INC

AI summary

An image reading device has an optical unit and a rail portion formed of sheet metal. The optical unit is scanned in the sub scanning direction to read an image on a document on a contact glass. The rail portion slidably supports the optical unit. The optical unit has a sliding portion which slides on the rail portion while making contact therewith, and at least one pair of gripping portions which grip the rail portion. The surface of the sliding portion has a substantially arc-shaped cross section. The rail portion has two inclined surfaces that make contact with the substantially arc-shaped surface at two points.