inkjet quality measurement

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New Developments in Instrumentation for Ink Jet

Analysis

Presented by: Yair Kipman

ImageXpert, Inc.Nashua, New Hampshire

www.imagexpert.com

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Outline

• Company description, markets we serve• Drop-in-flight measurement

– JetXpert- a machine vision based system for analysis of drops in flight

• Overview of other inkjet related products– Nozzle plate inspection– Print head alignment– Dot position analysis– Print quality and color measurement

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Company Description

• Since 1989, ImageXpert Inc. has been providing machine-vision solutions for automated image quality and part inspection for digital printers, consumables, and components to leading imaging companies throughout the world for use in in R&D and production environments

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Markets and ApplicationsWho can benefit from our technology? Developers of

printing systems and fluids for traditional and new inkjet applications.

The inkjet market is evolving beyond traditional printed materials to include:

• Printed electronics and display technology

• Biomedical applications:

– Micro dispensing

– Micro deposition

– Microarray fabrication

• Coatings

• Expansion of traditional marking applications:

– Variable data, hybrid printing systems

– Custom and vanity on-demand printing- décor, housewares, wall coverings…

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Measurement and visualization of drops-in-flight

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JetXpert System Benefits

• Single strobe event for imaging of single droplets

• Works with any print head• 125ns minimum pulse width• Second camera option for imaging of face plate

during firing (assess wetting)

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JetXpert System Description

• Fully integrated system includes:– LED strobe, optics, strobe control box, and strobe

control software (GUI)– Calibrated digital camera for image capture with

proprietary optics– ImageXpert software for image capture and drop

analysis

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JetXpert System Capabilities

• Works with any print head including those from Kodak, HP, Konica Minolta, Xaar, Spectra (Dimatix), Seiko and Epson.

• Control all aspects of strobing via custom GUI

• Settings communicated to strobe electronics via RS232

• Strobe frequency up to 100kHz

• Long delay times up to 20ms

• Minimum pulse width is 125ns

• Single, double and triple dot visualization and analysis

• Drop series visualization

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JetXpert System Capabilities

• Digital camera (1024 x 768 pixels) for image capture

• Calibration process (with calibration target) for accurate results reported in real-world units

• Camera shutter speed can be used to increase image contrast

• Digital strobe control system enables repeatable measurement at the same settings

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Strobe User Interface

The strobe user interface allows for easy control of all strobe characteristics such as :

– Number of pulses

– Pulse width– Delay times– Intensity

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Strobe User Interface

Select single, double or triple drops

Start or stop the strobe

Set delay times, pulse width, change shutter speed and intensity.

Visualize droplets in motion by using variable delay times.

Choose firing mode and trigger type

Automatically save image to file

Close the GUI window

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Theory of Operation

Print head drive frequency or internal frequency

Strobe pulse width

Str

obe

inte

nsity

Delay 2

Delay 1

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Single Strobe Event

Single event image of single droplet (left) vs. 4 drop aggregated droplet image (right).

Both images were taken with a strobe pulse width of 500ns.

Single droplet 4 droplets

Images from Kodak print head, #10 cartridge.

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Strobe Pulse Width

Single event images of droplet imaged with a pulse width of 500ns (left) vs. a strobe pulse width of 1500ns (right).

500ns 1500ns

Images from Kodak print head, #10 cartridge.

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Drop Analysis

• ImageXpert software allows for real-time, dynamic analysis of drops such as:– Droplet volume– Velocity– Trajectory– Ligature volume, length, break-off length

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Drop Analysis Example

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Sequential Imaging of Drops-in-Flight

• Both incremental and cyclic droplet motion can be imaged to offer insight into print head performance

Incremental motion:

Start time

Stop time Stop time

Start time

Cyclic motion:

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JetXpert Movie

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Measurement and visualization of drops-in-flight

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Other Ink Jet Applications• Part inspection• Print head alignment• Dot position• General print quality• Printed electronics

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Part Inspection: Nozzle Plates

• A line-scan camera is used for high speed, high magnification imaging of entire nozzle array

• Measurements can include nozzle shape, size, concentricity, alignment...

• Assess defects (clogs, debris, etc.)

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Print Head Alignment

• Uses one or more 2-D cameras

• Measure head angle and nozzle position

• Measure offset and angular displacement between heads or between each head and assembly on multiple-head systems

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Dot Position Analysis

• Using a line scan camera, large images of printed dot patterns can be captured in a single pass without step-and-repeat – High accuracy– High speed– Small footprint

• Dot position analysis often compares actual dot centroid positions to an ideal grid of locations:

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Dot Position Animation

• Here is a conceptual animation showing the dot position analysis process using line scan camera technology and ImageXpert software

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QuickTimeª and aTIFF (Uncompressed) decompressor

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Print Quality Analysis

• Line quality

• Dot quality

• Text quality

• Solid area

• Jet health

• Color bleed

• Satellites

• Graininess

• …

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Dot Quality

• Common dot quality measurements include:

– Size, shape (roundness and axis ratio), perimeter length (raggedness), darkness and position

• Both statistical data and data from the individual dots can be reported

• Dots and satellites can be measured separately

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Dot Quality

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Text Quality

Common features for assessing text quality include:

• Character area• Perimeter length• Edge raggedness• Detection of breaks • Detection of fill-ins

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Line Quality

Common line quality features include:

• Average line width• Edge raggedness• Edge sharpness• Line area• Line darkness

Since line quality is dependent on orientation, both vertical and horizontal lines are usually measured

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Inter-Color Bleed

Inter-color bleed is the unintentional intermixing of adjacent colorants.

Different color combinations often have different quality levels.

Common measurements include comparisons of:

• line width• edge raggedness• edge sharpness

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Solid Area Quality

Solid area mottle measurement methods include:

• Simple statistics (standard deviation)

• ISO/IEC 13660 using tiled cells or a “moving ROI”

• Cluster-based analysis

QuickTimeª and aTIFF (Uncompressed) decompressor

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Printed Electronics

• 2-D inspection using cameras or an A3 scanner for lead width and spacing, edge raggedness, extraneous material, voids, layer-to-layer registration, dimensional analysis…

• 3-D inspection using a laser triangulation system for evaluation of lead height, profiles, volume, and other topographic measurements

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Printed Electronics: Lead width

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Printed Electronics

• Bi-directional phase issues from ink jet printing:

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Printed Electronics

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Printed Electronics: Ink Volume Using Laser Triangulation Data

• Ink volume calculated: 0.808 microliter/ 5mm length

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Inspection Systems

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Scanner

Handheldcamera

Full motion: camera and laserand/or line scan

Yourmicroscope

Multi-anglecamera system

All hardware configurations use the same software

XXiJetXpert:Drop-in-flight

analysis system

Manual motioncamera system

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Research &Development

Production(QA/QC)

Benchmarking/Competitive analysis

Use in R&D and Production

ImageXpert systems offer:

• Objective, quantitative analysis necessary for competitive analysis

• Flexibility, interactive tools and powerful algorithms necessary for R&D

• Automation, reliability and repeatability necessary for production

XXi

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Innovations

• Our scanner-based system has duplex capabilities for automated analysis of second side

• 2048 x 2048 black and white camera option for automated and manual motion systems – Larger format camera can decrease inspection

time versus standard cameras by imaging larger areas in each picture

• Second camera option for JetXpert for face plate imaging, or full trajectory analysis of drops-in-flight

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www.imagexpert.cominfo@imagexpert.com

603-598-2500