Optical Print Head Relative Position Detection

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Solution Overview

Problem

Conventional methods for detecting the relative position of a light-emitting element substrate to a rod lens array in line optical type optical print heads are inadequate, particularly due to variance in rod lens diameters, limiting accurate positioning and leading to image defects like density unevenness.

Innovation Solution

A relative position detection method that involves causing light-emitting elements to emit light and detecting the optical intensity distribution at a position displaced from the image positions along the optical axis, allowing for precise positioning of the light-emitting member relative to the lens array or vice versa, irrespective of lens diameter variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the alignment mark on the light-emitting element substrate is matched to the outer circumferential line of the rod lenses, then the relative position detection can be performed, but error in positions occurs due to variance of diameters of the rod lenses

Engineering Contradiction:

Improverelative position detection accuracyVSAvoidpositioning accuracy

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

A new mark is introduced as an intermediary element that is not affected by rod lens diameter variations. This mark serves as a stable reference for position detection, mediating between the light-emitting element substrate and the rod lens array without being influenced by the variability of the rod lenses themselves.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The position detection reference is extracted from the rod lens array structure itself and separated into an independent mark on the light-emitting element substrate. This extraction eliminates the dependency on rod lens diameter for position detection, allowing the reference to be established independently of the rod lens variability.

Inventive Principle:

Principle #2Taking out (Extraction)

2Productivity

If the rod lenses are arrayed along the main scanning direction, then the line optical type optical print head can be constructed, but relative position detection can only be performed in the sub scanning direction

Engineering Contradiction:

Improveimage formation efficiencyVSAvoiddetection direction coverage

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The mark design incorporates features that extend in both the main scanning direction and the sub scanning direction, adding dimensional capability to the position detection system. This allows the same mark structure to provide reference information for position detection in both scanning directions simultaneously.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 method enables accurate detection and adjustment of the light-emitting element substrate's position relative to the rod lens array in both main and sub scanning directions, ensuring consistent image quality by compensating for lens diameter variations and preventing image defects.

Implementation Method 1

causing the light-emitting elements to emit light

Methodology Applied

Scientific EffectLight emission: Light

Implementation Method 2

detecting, at a position displaced from the image positions along an optical axis direction, optical intensity distribution of light emitted from the light-emitting elements and transmitted through the lens array

Methodology Applied

Scientific EffectLight transmission: Light

Implementation Method 3

the lens array includes lenses arranged in the first direction and condenses light emitted from the light-emitting elements to image positions of the light-emitting elements

Methodology Applied

Scientific EffectLight condensation: Lens

Data Source

PatentUS10737507B2Relative position detection method, optical print head, and image forming device

Publication Date: 2020.08.11 KONICA MINOLTA INC

AI summary

A relative position detection method detecting a position of a light-emitting member relative to a lens array or a position of the lens array relative to the light-emitting member, in which the light-emitting member includes light-emitting elements arranged in a first direction and the lens array includes lenses arranged in the first direction and condenses light from the light-emitting elements to image positions of the light-emitting elements, optical axes of the lenses being orthogonal to the first direction. The method includes: causing the light-emitting elements to emit light; detecting, at a position displaced from the image positions along an optical axis direction, optical intensity distribution of light emitted from the light-emitting elements and transmitted through the lens array; and detecting a position of the light-emitting member relative to the lens array or a position of the lens array relative to the light-emitting member with use of the optical intensity distribution.