Droplet Discharge Device Nozzle Error Testing

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Solution Overview

Problem

Conventional methods for testing droplet discharge devices, such as inkjet heads, face challenges in accurately determining the nozzle position and discharge angle due to the need for a transparent test sheet, which can lead to distorted liquid adherence and inaccurate detection, and are unable to assess deviations from the designed position effectively.

Innovation Solution

A method involving the use of a test sheet at different distances from the droplet discharge device to form dots at varying positions, allowing for the calculation of nozzle position or discharge angle errors without requiring a transparent sheet, enabling the selection of any test sheet type and improving accuracy by using a sheet with an ink-absorbing layer or smooth surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a transparent test sheet is used to photograph the nozzle and liquid adherence from the rear side, then the testing setup is simple, but the liquid adheres with a distorted shape and the position detection becomes inaccurate

Engineering Contradiction:

Improvetesting setup complexityVSAvoidposition detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent inverts the conventional transparent test sheet approach by using an opaque test sheet with a reflective layer. Instead of photographing from the rear side through a transparent sheet, the system photographs from the front side by reflecting light off the reflective layer, thereby eliminating distortion while maintaining testing simplicity

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces a reflective layer as an intermediary between the test sheet and the photographing system. This reflective layer enables accurate position detection by providing a clear reflection surface without requiring the test sheet to be transparent, thus resolving the contradiction between simplicity and accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If a transparent test sheet is used, then the testing method is straightforward, but the method cannot accurately test how much the nozzle position deviates from the designed position

Engineering Contradiction:

Improvetesting method simplicityVSAvoidnozzle position deviation measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-forming a reflective layer on the test sheet before conducting the droplet discharge test. This pre-prepared reflective surface enables accurate position deviation measurement from the outset, maintaining operational simplicity while achieving precise measurement capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the optical transmission-based measurement system (photographing through transparent sheet) with a reflection-based measurement system. This substitution enables accurate nozzle position deviation measurement while keeping the testing method straightforward

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If the test sheet is not provided flatly, then the setup is easier, but the CCD camera cannot accurately photograph the nozzle

Engineering Contradiction:

Improvetest sheet setup easeVSAvoidnozzle position detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The reflective layer acts as an intermediary that compensates for test sheet non-flatness. By reflecting light from the front side, it maintains accurate nozzle position detection even when the test sheet is not perfectly flat, thus easing setup requirements without sacrificing measurement precision

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach allows for precise determination of nozzle position and discharge angle errors, enabling the detection of abnormalities and variance in discharge velocity, enhancing the accuracy and flexibility of testing without the need for a CCD camera on the rear side of the test sheet.

Implementation Method 1

a second step of discharging at least one droplet toward the test sheet set in the first step from a nozzle formed in the droplet discharge device to form at least one first dot on the test sheet

Methodology Applied

Scientific EffectDroplet discharge:

Data Source

PatentUS7407255B2Method of testing a droplet discharge device

Publication Date: 2008.08.05 BROTHER KOGYO KK

AI summary

A test sheet is set in a droplet discharge device at a first distance. At least one droplet is discharged toward the test sheet from a nozzle formed in the droplet discharge device to form at least one first dot on the test sheet. The test sheet is set in the droplet discharge device at a second distance differing from the first distance. At least one droplet is discharged toward the test sheet from the nozzle to form at least one second dot on the test sheet. A nozzle position error or a nozzle discharge angle error are calculated from the position of the first dot, the position of the second dot, the first distance, and the second distance. Testing inkjet heads in this manner allows accurate testing for errors in nozzle position or discharge angle.