Image Reading Apparatus Inclined Background Shadow Detection
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Solution Overview
Problem
Conventional image reading apparatuses face challenges in accurately detecting document shadows due to their faint nature, which reduces detection accuracy.
Innovation Solution
The apparatus includes a conveyance member, a transparent member, and a background member with an inclined planar shape, where the light source emits light inclined downstream in the conveyance direction, allowing the reading sensor to read the shadow projected onto the background member through the transparent member, enhancing shadow detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional light source and background member configuration is used, then the apparatus structure is simple, but the shadow detection accuracy is reduced due to faint shadow formation
Solution Approach 1:
The patent introduces a third dimension by inclining the background member at a specific angle (α) relative to the sheet conveyance direction. This angular inclination transforms the two-dimensional shadow projection into a three-dimensional optical path configuration, enhancing shadow contrast by creating a longer optical path through the shadow region and reducing background interference.
Solution Approach 2:
The patent changes the geometric parameter of the background member from a conventional horizontal or vertical orientation to a specific inclined angle (α). This parameter change optimizes the shadow formation by adjusting the angle between the light source, sheet, and background member, thereby enhancing shadow detection accuracy without requiring complex additional components.
2Measurement precision
If the shadow is faint in conventional configurations, then the apparatus is simple to operate, but the detection accuracy of the shadow is reduced
Solution Approach 1:
By inclining the background member at angle (α), the patent creates an extended optical path in the third dimension, allowing the reading sensor to detect shadows with enhanced contrast. The inclined configuration increases the path length of light through the shadow region, amplifying the optical density difference and improving detection accuracy.
Solution Approach 2:
The inclined background member acts as an intermediary element that mediates between the light source and the reading sensor. It transforms the faint shadow into a more detectable form by creating a geometric configuration that enhances shadow projection and reduces background light interference, thereby improving shadow contrast without modifying the light source itself.
3Measurement precision
If the light source emits light perpendicular to the sheet, then the illumination is uniform, but the shadow projection onto the background member is faint and difficult to detect
Solution Approach 1:
The patent introduces asymmetry in the optical configuration by inclining the background member at angle (α) relative to the sheet. This asymmetric arrangement creates a non-uniform light path distribution that enhances shadow contrast, as the inclined background member intercepts light at angles that maximize shadow projection visibility while maintaining sufficient illumination on the sheet.
Solution Approach 2:
The inclined background member adds a dimensional component to the shadow projection geometry. Instead of projecting shadows directly onto a flat surface perpendicular to the light source, the inclined configuration extends the projection path in three-dimensional space, enhancing shadow visibility and detection accuracy through increased optical path length and reduced background interference.
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 improves the detection accuracy of document shadows, leading to more precise digital skew correction and image formation by increasing the contrast between the background and shadow.
Implementation Method 1
the reading sensor being configured to read a shadow, projected onto the background member, of a sheet
Implementation Method 2
an image of the sheet through the transparent member
Data Source
AI summary
An image reading apparatus includes a conveyance member, a transparent member, a background member, and a reading unit. The reading unit arranged on an opposite side to the background member with respect to the transparent member. The reading unit includes a light source and a reading sensor. The light source emits light toward a sheet. The reading sensor reads a shadow of a sheet and an image of the sheet through the transparent member. The shadow of the sheet is projected onto the background member. As viewed in a width direction perpendicular to a conveyance direction, an irradiating direction of the light inclines downstream in the conveyance direction toward a downstream side in the irradiating direction. The background member has a planar shape that is inclined to approach the transparent member from an upstream side toward a downstream side in the conveyance direction.