Image Reader Optical Layout for Depth of Field and Stray Light
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Solution Overview
Problem
The depth of field in image reading devices decreases when the opening is enlarged to increase the amount of light received by light-receiving pixels.
Innovation Solution
An image reading device is designed with a plurality of light-receiving pixels, a first light-shielding member with first openings, a second light-shielding member with second openings, and condenser lenses disposed between the openings and the reference surface, allowing reflected light to sequentially pass through the condenser lenses, second openings, and first openings before entering the light-receiving pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the opening is enlarged to increase the amount of light received by light-receiving pixels, then the amount of light received is improved, but the depth of field decreases
Solution Approach 1:
The patent divides the single opening into multiple openings (first openings and second openings) arranged in a specific pattern. This segmentation allows each opening to be smaller, maintaining depth of field, while the collective arrangement of multiple openings provides sufficient light transmission area to increase the amount of light received by the light-receiving pixels.
Solution Approach 2:
The patent employs a nested structure where the first light-shielding member with first openings is positioned between the light-receiving pixels and the reference surface, and the second light-shielding member with second openings is positioned between the first openings and the reference surface. This nested arrangement of multiple shielding members with openings creates a multi-level light control structure that maintains depth of field while enabling sufficient light reception.
2Illumination intensity
If the opening is enlarged to increase the amount of light received, then the amount of light received is improved, but image degradation from stray light occurs
Solution Approach 1:
By segmenting the opening into multiple smaller openings arranged in specific patterns, the patent reduces stray light entry while maintaining sufficient light transmission. The segmented structure allows for better control of light paths, preventing off-axis light from entering the light-receiving pixels while still providing adequate illumination intensity.
Solution Approach 2:
The patent introduces light-shielding members as intermediary structures between the reference surface and the light-receiving pixels. These intermediaries (first and second light-shielding members with openings) act as mediators that selectively transmit desired light while blocking stray light, thus improving image quality by preventing harmful stray light from reaching the sensor.
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 increases the depth of field while maintaining or increasing the amount of light received by light-receiving pixels, preventing image degradation from stray light and enhancing image quality.
Implementation Method 1
a plurality of condenser lenses disposed between the plurality of second openings and the reference surface and disposed at a distance from the plurality of second openings, wherein the plurality of first openings are arranged to correspond to the plurality of light-receiving pixels respectively, the plurality of second openings are arranged to correspond to the plurality of light-receiving pixels respectively, the plurality of condenser lenses are arranged to correspond to the plurality of light-receiving pixels respectively
Data Source
AI summary
An image reading device includes a plurality of light-receiving pixels configured to receive reflected light; a first light-shielding member including a plurality of first openings and disposed between the plurality of light-receiving pixels and a reference surface; a second light-shielding member including a plurality of second openings and disposed between the plurality of first openings and the reference surface; and a plurality of condenser lenses disposed at a distance from the plurality of second openings. The plurality of condenser lenses, the second light-shielding member, the first light-shielding member, and the plurality of light-receiving pixels are disposed at positions at which reflected light sequentially passes through one of the condenser lenses corresponding to each light-receiving pixel, one of the second openings corresponding to the each light-receiving pixel, and one of the first openings corresponding to the each light-receiving pixel and enters the each light-receiving pixel.