Line Head Inkjet Printer Nozzle Block Correction

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Solution Overview

Problem

In line head inkjet printers, variations in ink ejection from nozzles cause density irregularities in printed images due to inaccuracies in nozzle production, ink flow path shapes, and actuator characteristics, which optical sensors struggle to detect, especially when the print medium's surface state varies.

Innovation Solution

A method that measures the ink ejected from each block of nozzles in a line head inkjet printer to calculate correction factors, ensuring consistent ink ejection by dividing the ink ejection surface into blocks and using a simpler measurement device than optical sensors, thereby reducing production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical sensors are used to detect printing results for ink ejection correction, then density irregularity can be reduced, but measurement accuracy deteriorates when the print medium surface state varies

Engineering Contradiction:

Improvedensity uniformityVSAvoiddot shape detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the optical detection system with a mechanical measurement system. Specifically, it uses a measurement head that physically contacts the print medium to measure ink ejection amounts directly, substituting optical detection with mechanical measurement to avoid surface state interference.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a measurement head as an intermediary device between the inkjet head and the print medium. This measurement head includes measurement nozzles that receive ink from the inkjet nozzles and transfer it to a measurement medium, serving as a mediator to enable accurate measurement without direct contact between the detection system and the variable surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If optical sensors are used to detect printing results, then ink ejection correction can be achieved, but production cost increases

Engineering Contradiction:

Improvedensity uniformityVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs a measurement medium that is inexpensive and can be discarded after use. The measurement medium is a simple substrate that receives ink for measurement purposes, replacing expensive optical sensors with a low-cost consumable item.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Productivity

If the ink ejection surface is elongated for single-pass printing, then productivity increases, but variation in ink ejection amount increases

Engineering Contradiction:

Improveprinting speedVSAvoidink ejection uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent divides the ink ejection surface into multiple independent measurement regions, each with its own measurement nozzles and measurement media. This segmentation allows for localized measurement and correction of ink ejection variations across the elongated surface, maintaining precision while enabling high productivity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7500729B2Method for correcting an amount of ejected ink in line head inkjet printer

Publication Date: 2009.03.10 BROTHER KOGYO KK

AI summary

A method for correcting an amount of ejected ink in a line head inkjet printer, includes measuring an amount of ink ejected from each block including at least one nozzle, nozzles formed in an inkjet head, the nozzles divided into the blocks; and obtaining a correction factor for each block on a basis of the measured amount of ejected ink in each block. The correction factors make a difference among the blocks in that an amount of ejected ink per nozzle becomes small.