Rod Lens Array Refractive Index Distribution for High Resolution Imaging

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Solution Overview

Problem

Conventional lens arrays used in high-resolution image forming apparatuses suffer from insufficient contrast between bright and dark sections, leading to deteriorated image quality due to fluctuations in the refractive-index distribution and light absorbing layer thickness, particularly at high resolutions like 1200 dpi.

Innovation Solution

A lens array is formed with rod lenses having a refractive-index distribution and an effective radius, where the outer periphery is modified by etching and roughening, and a filler is applied to stabilize optical characteristics, with specific radius ratios and light-impervious portions to control light scattering and improve resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light absorbing layer is formed using a dye to improve image quality, then the contrast between bright and dark sections improves, but the thickness variation occurs making it difficult to form a uniform layer

Engineering Contradiction:

Improvecontrast between bright and dark sectionsVSAvoidthickness uniformity of light absorbing layer

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent extracts the light-absorbing function from a separate dye layer and integrates it into the rod lens material itself. By incorporating a light absorbent into the resin or glass material during manufacturing, the need for a separate light absorbing layer is eliminated, thus avoiding thickness uniformity issues while maintaining the contrast improvement benefit

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses composite materials by combining the resin or glass base material with a light absorbent substance. This creates a unified material that simultaneously provides structural integrity and light-absorbing properties, eliminating the interface between separate layers and ensuring uniform optical characteristics throughout the rod lens

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If the outer periphery of rod lenses is removed to improve optical characteristics, then image quality improves, but the manufacturing complexity increases

Engineering Contradiction:

Improveoptical characteristics uniformityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent performs preliminary action by incorporating the light absorbent into the rod lens material during the initial manufacturing process, before the rod lenses are assembled into the array. This preliminary incorporation of the light-absorbing property eliminates the need for subsequent complex processing steps to add light-absorbing layers or modify the rod lens periphery

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent merges the light-absorbing function with the rod lens structural function by integrating the light absorbent into the rod lens material itself. This consolidation eliminates the need for separate light-absorbing components or complex multi-step manufacturing processes, simplifying both the device structure and manufacturing workflow

Inventive Principle:

Principle #5Merging (Combining)

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

The solution achieves clear images with high contrast and improved printing characteristics by stabilizing optical characteristics and controlling light scattering, effectively addressing the issues of granular quality and blur in high-resolution imaging.

Implementation Method 1

A rod lens is an optical lens made of a cylindrical-shaped resin or glass material with a refractive-index distribution in a radial direction

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

The light absorbing layer contains a light absorbent for absorbing at least part of the light transmitted through the rod lens

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS7630137B2Lens array, exposure device, and image forming apparatus

Publication Date: 2009.12.08 OKI ELECTRIC INDUSTRY CO LTD

AI summary

A lens array has a plurality of rod lenses with optical axes in parallel with one another, in which the rod lens has a refractive-index distribution in a radial direction. The lens array has a radius ratio r0/r set to 0.9 or smaller, in which a radius r of the rod lens is set as the radius of the rod lens when the refractive-index distribution is formed, and in which a radius r0 of the rod lens is set as the radius of the rod lens when all or part of an outer periphery of the rod lens is removed after formation of the refractive-index distribution.