Document - Allied Vision Technologies
Document - Allied Vision Technologies
Document - Allied Vision Technologies
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AVT Best Practice ImageXpert, USA<br />
Drop<br />
by Drop<br />
Inspection<br />
ImageXpert<br />
Since 1989, ImageXpert Inc. of Nashua, NH (USA) has been producing image quality measurement<br />
software and hardware systems for print and part quality assessment. The expertise<br />
of the company includes machine vision, motion control, printing technology, software development,<br />
image quality analysis, imaging science, optics, illumination, systems integration<br />
and applications engineering.<br />
The Challenge: Achieve Perfect Ink Jet Control For High Quality Prints<br />
Thanks to dropping prices as well as the boom in internet and digital photography use, ink-jet printers can now be found next to computers<br />
in almost every household. With just one push of a button, documents and images can be quickly and easily put to paper. As users,<br />
we can easily forget what a major technical achievement lies behind this now everyday printing activity: the controlled and highly precise<br />
spraying of ink onto paper via millions of tiny ink drops that combine to form the print image. Whether with bubble jet or piezoelectric<br />
technology, printer and print head manufacturers face the challenge of perfectly controlling the size, speed and trajectory of the droplets<br />
to produce clean, sharp, photo-quality images.<br />
The Solution: JetXpert With Digital Image Processing<br />
To support companies using print heads from manufacturers such as Dimatix, Xaar, Kyocera, Konica-Minolta, Epson and Ricoh in their<br />
development and quality control, ImageXpert developed a system to precisely analyze a print head’s ink jet with the aid of cameras and<br />
proprietary LED strobing technology and analytical software.<br />
The JetXpert system is available in a one-camera or two-camera configuration using digital cameras<br />
from <strong>Allied</strong> <strong>Vision</strong> <strong>Technologies</strong>. In the one-camera option, the print head is positioned at a 90°<br />
angle to the camera axis in front of the camera so that the jetted droplets pass between the<br />
camera lens and an LED strobe unit. ImageXpert developed a special strobe controller to<br />
synchronize the illumination of the droplets such that the light strobes at a specified time delay<br />
after the firing pulse. The LED is positioned behind the ink<br />
droplet so the image of the droplet is in<br />
silhouette, which allows for analysis of both<br />
transparent and opaque fluids.<br />
The strobe pulsewidth is, at 250 ns,<br />
particularly short. “Once the drops are ejected,<br />
they move at a speed of approximately 10<br />
meters per second“, explains Yair Kipman,<br />
President of ImageXpert. “The very short strobe<br />
width allows us to capture images with minimal<br />
motion blur.”
JetXpert uses single strobe events, one strobe per image<br />
frame, to capture images of individual droplets in flight.<br />
This method of image capture is made possible by the<br />
proprietary high-powered LED, and minimizes blur caused<br />
by droplet aggregation that is common to systems that use<br />
multiple strobes per frame.<br />
Customer Satisfaction:<br />
AVT Guppy Follows AVT Stingray<br />
The camera is a Stingray F-080b model by <strong>Allied</strong> <strong>Vision</strong><br />
<strong>Technologies</strong>. This monochromatic camera is equipped with<br />
an XGA (0.8 megapixel) image sensor and a high-speed<br />
FireWire IEEE1394b interface. “The Stingray F-080 delivers<br />
30 frames per second,” according to Kipman. “What was<br />
really most valuable for us, however, was the ability to<br />
freely set the shutter speed between 48 µs and 67 s. By<br />
being able to change the shutter speed, we can work with very fast ejection systems such as ink jet technology and much slower dispensing<br />
systems such as those used in the fabrication of bioarrays.”<br />
The camera is equipped with a Moritex telecentric zoom lens, assuring that small variations in the depth of the ink jet in the image does<br />
not lead to a change in scale. The ink jet’s trajectory is measured relative to the angle of the print head, but analysis of the full trajectory<br />
of drops in flight is only possible with images captured with the two-camera version of the system.<br />
“We are extremely satisfied with the performance of the AVT Stingray. This is<br />
why we chose the AVT Guppy for an even more compact version of JetXpert.”<br />
Yair Kipman, President of ImageXpert, Inc.<br />
The overall system footprint is quite small for inclusion in R&D and production environments, but applications exist where an even smaller<br />
configuration is desired. “We are extremely satisfied with the performance of the AVT Stingray cameras”, says Yair Kipman. “This is why we<br />
chose the Guppy, another AVT camera with a very small form factor, to design a more compact version of JetXpert for applications where little<br />
space is available”.<br />
Implementation in Practice: From Printer Manufacturers to Biotechnologies<br />
The camera’s images are transferred to the system computer via the Stingray’s FireWire interface. There, software developed by ImageXpert<br />
analyzes the images to measure important qualities of the droplets such as: drop volume, trajectory, velocity, ligature length, break off<br />
length, etc. The drop volume (in picoliters) is calculated based on the measured drop radius. Velocity is most often calculated from the<br />
distance and time interval between two drops with a known delay time between them. The system measures the ink jet’s trajectory relative<br />
to the print head in either two or three dimensions.<br />
The JetXpert System is already in use by many leading printer and ink manufacturers, and is relevant in markets and research where liquid<br />
material is jetted or dispensed, such as printable electronics, adhesives or biotechnology.<br />
<strong>Allied</strong> <strong>Vision</strong> <strong>Technologies</strong> in the USA<br />
<strong>Allied</strong> <strong>Vision</strong> <strong>Technologies</strong>’ subsidiary <strong>Allied</strong> <strong>Vision</strong> <strong>Technologies</strong> Inc. in Newburyport, MA is in charge of sales and support activities for<br />
AVT cameras in the Americas. Besides AVT Inc.’s own sales team, a network of distributors and resellers offer local service to North American<br />
customers. ImageXpert was supplied and supported by 1st<strong>Vision</strong> Inc.<br />
1st<strong>Vision</strong><br />
2 Dundee Park<br />
Andover, MA 01810<br />
Tel.: +1-978-4740044<br />
Fax.: +1-978-6237260<br />
Email: info@1stvision.com<br />
Internet: www.1stvision.com<br />
ALLIED VISION TECHNOLOGIES GMBH<br />
Taschenweg 2a | 07646 Stadtroda | Germany<br />
Phone: +49 36428/677-0 | Fax: +49 36428/677-14<br />
ALLIED VISION TECHNOLOGIES INC.<br />
38 Washington Street | Suite 2 | Newburyport, MA 01950 | USA<br />
Phone (toll free North America): 1-877-USA-1394 | Phone: +1-978-225-2030<br />
www.alliedvisiontec.com | info@alliedvisiontec.com