Image Reading Apparatus Rod Lens Array Chromatic Aberration
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Solution Overview
Problem
Conventional image reading apparatuses using reduction optical systems or non-magnification optical systems face challenges in achieving optimal imaging performance due to chromatic aberration and light efficiency, particularly in maintaining accurate reflection and light passage across the image reading area.
Innovation Solution
The image reading apparatus incorporates a reflection mirror unit with multiple reflection areas and a beam regulating aperture unit, along with a line image sensor with successively arranged light receiving areas, to ensure accurate reflection and light passage, reducing chromatic aberration and enhancing light efficiency by using a telecentric optical system and light shielding to prevent image blur and flare phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a reduction optical system is used, then the image reading area can be enlarged, but chromatic aberration increases and imaging precision deteriorates
Solution Approach 1:
The optical system is segmented into multiple rod lenses arranged in an array, each rod lens independently imaging a portion of the reflected light. This segmentation approach eliminates chromatic aberration by using multiple discrete optical paths rather than a single reduction lens system, thereby maintaining imaging precision while enabling a larger image reading area.
2Area of stationary object
If a reduction optical system is used, then the image reading area can be enlarged, but the system complexity increases due to multiple mirrors and lenses
Solution Approach 1:
The invention extracts and eliminates the complex mirror system from the optical path by using a rod lens array that directly images reflected light from the document surface. This extraction of unnecessary components (mirrors and reduction lenses) simplifies the system while maintaining the ability to read images from a large area.
3Measurement precision
If light shielding is increased to prevent flare, then image quality improves, but light efficiency decreases
Solution Approach 1:
The aperture unit is designed with local quality by providing specific light shielding portions only where needed to prevent flare and ghost images, while leaving other areas open for light passage. This selective light shielding maintains image quality by blocking unwanted light paths while preserving light efficiency by allowing necessary light to reach the image 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 enhances imaging performance by minimizing chromatic aberration, reducing the need for high illuminance, and preventing image blur and flare, resulting in improved depth of field and energy efficiency.
Implementation Method 1
The reflection mirror unit reflects the reflected light from the document to the photoelectric converter and images the reflected light on the photoelectric converter
Implementation Method 2
The aperture unit is arranged on an imaging optical path from the reflection mirror unit to the photoelectric converter. This aperture unit includes a light shielding portion having light shielding properties
Implementation Method 3
a line image sensor configured to convert each optical image into an electrical signal
Data Source
AI summary
An image reading apparatus includes a light irradiator, an optical system and a photoelectric converter. The optical system includes a reflection mirror unit and an aperture unit. The reflection mirror unit includes first and second reflection areas successively provided in a main scanning direction. The aperture unit includes a light shielding portion and first and second light passing holes for allowing the passage of the light reflected by each of the first and second reflection areas. The photoelectric converter includes a light receiving surface having first and second light receiving areas configured to receive the light passed through each of the first and second light passing holes and successively arranged in the main scanning direction. A length of the light receiving surface along the main scanning direction is set to be equal to or longer than that of the image reading area along the main scanning direction.