Inkjet Head Ejection Timing Control for Landing Deviation

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Solution Overview

Problem

Existing image formation apparatuses, such as inkjet recording devices, face challenges in maintaining image quality due to landing deviation caused by conveyance and self-produced airstreams, which cannot be effectively resolved by simply controlling the ejection speed of ink droplets.

Innovation Solution

An image formation apparatus that adjusts ink ejection timing based on the self-produced airstream rate, using a calculation of the volume of ink ejected per unit time and a correction coefficient, to counteract the effects of both conveyance and self-produced airstreams, thereby improving landing position accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If uniform control to increase ejection speed is applied to all ink droplets, then landing deviation for some droplets is reduced, but landing deviation for other droplets increases due to varying self-produced airstream generation

Engineering Contradiction:

Improvelanding position accuracyVSAvoidadaptability to varying ejection patterns

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The ejection speed is made dynamic rather than uniform. The control unit adjusts the ejection speed based on the number of ink droplets to be ejected, creating a variable ejection speed that adapts to different ejection patterns. This resolves the contradiction by making the system flexible enough to handle both high-volume continuous ejection (where self-produced airstream is strong) and sparse ejection (where self-produced airstream is weak), optimizing landing position accuracy for each scenario.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The ejection speed parameter is changed based on the ejection pattern. When a large number of droplets are to be ejected continuously, a higher ejection speed is applied to counteract the strong self-produced airstream. When fewer droplets are ejected, a lower ejection speed is used. This parameter adjustment resolves the contradiction between maintaining precision across different ejection volumes.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If ejection speed is increased to counteract conveyance airstream, then landing deviation from conveyance airstream is reduced, but the effect varies depending on self-produced airstream generation

Engineering Contradiction:

Improvelanding position accuracyVSAvoidinfluence of self-produced airstream

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The control unit uses feedback about the ejection pattern (number of droplets to be ejected) to adjust the ejection speed. This feedback mechanism allows the system to anticipate the strength of the self-produced airstream and compensate for it by adjusting the ejection speed accordingly, resolving the contradiction between counteracting conveyance airstream and accounting for self-produced airstream variations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The ejection speed is determined in advance based on the planned ejection pattern before actual ejection occurs. The control unit calculates the appropriate ejection speed considering the number of droplets to be ejected, allowing preliminary compensation for the self-produced airstream effect before it actually influences the droplet trajectory.

Inventive Principle:

Principle #10Preliminary action

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 effectively reduces landing deviation, ensuring high image quality by accurately adjusting ink ejection timing to account for the influence of both airstreams, resulting in a good image free from landing deviation.

Implementation Method 1

an airstream W2 (hereinafter called a self-produced airstream) flowing from the ink head 120 toward the recording medium is generated at the position right below the ink head 120 when the ink droplets 20 are ejected from the nozzle 121

Methodology Applied

Scientific EffectSelf-produced airstream:

Implementation Method 2

an airstream W1 (hereinafter called a conveyance airstream) flowing from upstream to downstream in a conveyance direction of a recording medium is generated when the recording medium is conveyed at a position just below the recording head

Methodology Applied

Scientific EffectConveyance airstream:

Data Source

PatentUS9114608B2Image formation apparatus

Publication Date: 2015.08.25 RISO KAGAKU CORP

AI summary

Included are: a storage unit configured to store profile data in which the amount of landing deviation and the ejection frequency representing the number of ejections of ink droplets per unit time are associated with each other; a correction judgment unit configured to determine whether to allow ejection timing control in print processing by selecting 30 dots as a unit line in an image, adding up a total volume of ink ejected to the unit line, and comparing the total volume of ejected ink with a predetermined threshold; and an ejection control unit configured to obtain the ejection frequency for ejecting ink at a predetermined time interval, from the total volume of ink ejected in the unit line, calculate the amount of landing deviation from the ejection frequency, and control the ejection timing in accordance with the calculated amount of landing deviation.