Bi-directional Printing Offset Calibration

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Solution Overview

Problem

In bi-directional printing, the print head tilts with respect to the sub-scanning direction during forward and reverse movements, leading to a decline in image quality due to misalignment of printing positions, which existing methods fail to adequately address.

Innovation Solution

An image forming device with a print head, head moving mechanism, and memory units to determine and correct offset values for each direction, adjusting the conveying distance to align printing positions accurately, thereby preventing tilting and maintaining image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If bi-directional printing is performed with a reciprocating print head, then printing productivity is improved, but printing position alignment deteriorates due to head tilting in different directions

Engineering Contradiction:

Improveprinting productivityVSAvoidprinting position alignment

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary calibration by printing test patterns in both forward and reverse directions, then calculating offset values before actual printing. This preliminary measurement of head tilting allows the system to pre-compensate for positioning errors, ensuring accurate alignment while maintaining bi-directional printing efficiency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent dynamically adjusts conveying amounts based on direction-specific offset values. By changing the conveying parameter differently for forward and reverse printing based on pre-measured tilting characteristics, the system compensates for head tilting and maintains precise printing position alignment throughout bi-directional operation

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If inexpensive mechanical structure is used, then device cost is reduced, but printing position stability deteriorates due to head tilting during reciprocation

Engineering Contradiction:

Improvedevice costVSAvoidprinting position stability

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The system performs self-calibration by automatically measuring its own head tilting characteristics through test printing, then using these measurements to correct positioning errors. This self-service approach allows inexpensive mechanical structures to achieve high precision without requiring complex mechanical stabilization mechanisms

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent implements a feedback mechanism where offset values measured during calibration are stored and applied during subsequent printing operations. This feedback loop allows the system to continuously compensate for mechanical imperfections, maintaining stable printing positions despite using cost-effective mechanical components

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8277010B2Image forming device that performs bi-directional printing while calibrating conveying amount of recording medium

Publication Date: 2012.10.02 BROTHER KOGYO KK

AI summary

An image forming device performs a bi-directional printing operation and includes a unit that determines a first amount by calibrating a predetermined amount based on a first value relating to a positional offset of a print element, and a unit that determines a second amount by calibrating the predetermined amount based on a second value relating to a positional offset of another print element. A recording medium is conveyed in a conveying direction the first amount after one of forward and reverse prints and the second amount after the other of the forward and reverse prints.