Telecentric Microlens Layout for Stable Image Reading Depth of Field
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Solution Overview
Problem
The existing image reading devices suffer from a decrease in depth of field and precision of image processing due to the inclination of microlens optical axes, which affects the overlap of visual fields between adjoining imaging optical systems, especially when the distance between the light receiving part and the subject changes.
Innovation Solution
The image reading device is designed with object-side telecentric microlenses, a zigzag pattern of light receiving pixel units, and strategically arranged light blocking members to ensure that light reflected by the object enters the correct light receiving pixels, maintaining image quality and increasing the depth of field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the optical axis of each microlens is inclined with respect to a direction orthogonal to the XY plane, then the resolution increases, but the depth of field decreases and precision of image processing deteriorates when the distance between the light receiving part and the subject changes
Solution Approach 1:
The patent changes the optical configuration parameter from an inclined optical axis to an object-side telecentric optical axis. This parameter change allows the microlens array to maintain a fixed optical axis orientation while achieving the desired resolution, thereby resolving the contradiction between resolution and depth of field.
2Manufacturing precision
If the optical axis of each microlens is inclined with respect to a direction orthogonal to the XY plane, then the resolution increases, but the precision of image processing deteriorates when the distance between the light receiving part and the subject changes
Solution Approach 1:
The patent changes the optical configuration parameter from an inclined optical axis to an object-side telecentric optical axis. This parameter change ensures that the optical axis remains orthogonal to the XY plane, thereby maintaining consistent image processing precision across different object distances while preserving resolution.
3Adaptability or versatility
If the distance between the light receiving part and the subject changes, then the overlap of visual fields between adjoining imaging optical systems changes, but this causes precision of image processing to deteriorate
Solution Approach 1:
The patent changes the optical configuration to object-side telecentric, which makes the visual field overlap between adjoining imaging optical systems invariant to object distance changes. This parameter change allows the system to adapt to different distances while maintaining consistent image processing precision.
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 enhances the depth of field while improving resolution and preventing visual field overlap or loss between microlenses, ensuring accurate image capture regardless of distance changes.
Implementation Method 1
a plurality of microlenses arrayed corresponding respectively to the plurality of first openings. Each microlens included in the plurality of microlenses is object side telecentric
Data Source
AI summary
An image reading device includes a plurality of light receiving parts arrayed regularly, a first light blocking member including a plurality of first openings arrayed corresponding respectively to the plurality of light receiving parts, and a plurality of microlenses arrayed corresponding respectively to the plurality of first openings. Each light receiving part included in the plurality of light receiving parts includes a plurality of light receiving pixels arrayed in a first direction as a main scanning direction. Each microlens included in the plurality of microlenses is object side telecentric. The plurality of microlenses, the first light blocking member and the plurality of light receiving parts are arranged so that light reflected by an object and passing through the microlens and the first opening corresponding to the microlens enters the plurality of light receiving pixels included in the light receiving part corresponding to the first opening.