Camera Options Increase for Machine Vision Applications
| By: Winn Hardin, Contributing Editor
The combination of cheaper, larger sensors - thanks to maturing semiconductor manufacturing processes and an explosion of digital interfaces - is pushing machine vision camera suppliers to broaden their product offerings. But is having more options always a good thing?
According to Michael Cyros, Chief Commercial Officer of Allied Vision Technologies (AVT), a Stadtroda, Germany-based provider of high-performance digital cameras for image processing, diversification among machine vision cameras is both a benefit and challenge to the growing machine vision market. With a growing, diverse customer base wanting more camera variations for their own needs, customers will be challenged to find the right camera, requiring suppliers to step up as consultants and offer more guidance than ever before.
More Pixels, But Bigger, Too?
The first of several trend drivers is the need for increased resolution, oftentimes combined with the need for increased sensitivity, Cyros notes. This is leading to higher-resolution sensors as well as larger optical formats, reaching beyond the needs of traditional C-mount optical formats.
Much of this push is coming from high-end applications - printed circuit board inspection, flat panel inspection, and so on - mainly so users can inspect more and more detail in these areas.
“What they have to inspect keeps getting smaller and smaller, which means more pixels, which means more cameras per system,” says Mark Butler, Product Manager with Teledyne Dalsa, a Waterloo, Canada-based provider of digital imaging solutions, including cameras and frame grabbers. “It’s getting to the point where the number of cameras is getting unwieldy.” As a result, he notes, manufacturers have been trying to get more pixels into a camera.
The need for larger sensor arrays is pushing some camera makers toward pixel shrink. “In some cases, the objects users are looking at are so small, it’s to their benefit for us to shrink the pixel because that will help to lower their optics cost,” Butler says. “We’re always trying to manage that - how large the pixels should be relative to the cost of the optics and so forth.”
Rick Roszkowski, Senior Director of Marketing, Vision Systems Business Unit at Cognex Corp.'s West Allis, Wisconsin facility, specializes in Cognex’s In-Sight smart cameras, including the DataMan AutoID image-based code readers. His customers want to be able to read barcodes across an entire carton or pallet at one time. This means cameras with higher resolutions.
“VGA is losing favor to 1.3- and 2-megapixel [MP] cameras, which puts more pressure on the storage if you’re keeping images, and processing capabilities as well,” Roszkowski explains. “Processing 120 barcodes at once can take 2.5 seconds, for example. So, in some cases, customers are saving the images and performing post-processing offline to determine whether a bad printhead is the cause of a defective barcode. The image-based reader runs faster than the case packer, so that’s not a problem. But for more detailed image analysis, sometimes it makes sense to run that offline.”
More Pixels, More Bandwidth, Please
“We’re redesigning some of our camera front ends to deliver both increased resolution without sacrificing frame rate and speed, such as our new SP-5000 5-MP camera that can go up to 209 frames per second today and will go to 250 frames per second very soon,” says Steve Kinney, Director of Technical Pre-Sales at JAI, Inc., a San Jose, California-based provider of digital CCD/CMOS camera technology.
The advent of CMOS sensors is allowing camera designers to cost-effectively adopt larger sensors that operate at higher frame rates. “The growing selection of high-resolution global shutter CMOS sensors is starting to displace traditional CCD sensors in certain applications,” says AVT’s Cyros. “The image quality of these new generations of CMOS sensors has made remarkable improvements in recent years, which is why we are finally seeing a big increase in demand for CMOS sensors for higher performance-type applications, instead of just the low-end application price points where CMOS traditionally fits.”
The most common way to offer more resolution while maintaining costs is to leverage improvements in semiconductor manufacturing and volumes to reduce cost or shrink the pixel size.
New high-speed, high-performance line-scan imaging cameras such as JAI’s SW-2000 2k line-scan camera with 20-micron pixels present another option. “That’s 400 square microns of active area compared with 50 for a 7-micron pixel,” Kinney explains. “And that means eight times the sensitivity improvement or throughput speed, or some combination thereof.”
The higher speed of new digital interface specifications is helping companies like JAI, Teledyne DALSA, and AVT to push camera designs into new territory, opening up new application areas. But it can make it more challenging for customers to choose the right combination.
“Since Camera Link, there have been a number of new standards available,” notes Cyros. “Rather than converging, each interface finds its way into certain application areas. Today, users are faced with a range of standards choices, including GigE Vision, USB3 Vision, and CoaXPress, in addition to Camera Link and others. This presents a challenge for a camera manufacturer that wants to address a wider range of the market.”
Cyros also points to the growing use of machine vision camera technology in non-industrial application markets to illustrate his point. “There are many newer applications such as specializations in medical, ITS (intelligent transportation systems), sports, and entertainment that require precise image capture in difficult lighting conditions, often in harsh environments, that are benefitting from the feature sets that are relied upon by the traditional machine vision market needs.
“In the end, this wide range of trends promises to keep things interesting for camera manufacturers as we all seek to find ways to differentiate ourselves from each other,” Cyros concludes. “This will likely lead to continued fragmentation in the camera market, making it difficult for camera manufacturers to achieve dominant positions. Combined with an increasingly lower barrier to entry for new camera suppliers, along with a growing range of interface standards and applications types, the camera user may be finding it increasingly difficult to make the right camera choice for their application needs, putting additional pressure on camera manufacturers to make sure their customers understand the unique performance of each model and guide the customer to the right selection.”