The engineering school where I went to college had a massive granite staircase known as the Approach. At that time, in the late 1970s, the saying went that you could drop-kick a Hewlett-Packard calculator down the Approach and it would still work.
Dave Novak, Hewlett-Packard’s LaserJet hardware test lab operations manager, doesn’t kick printers off the bluff next to the Boise, Idaho, facility where he is responsible for printer testing. But if he doesn’t, it’s likely only because nobody’s asked him to. Printers go through a rigorous series of tests, both for performance and to comply with regulatory requirements around the world. The objective of the organization is to deliver products that are safe, compliant, reliable and perform to their specifications, he says.
Boise was chosen as the HP printer facility in 1972, due to “its proximity to the San Francisco Bay Area, the city’s attractiveness, quality of life, welcoming attitude, and a local college equipped to train technical workers,” according to an HP company magazine. (Disk drives were manufactured there for a while, too.) The company campus is located on 220 acres west of Boise and consists of six buildings. During its heyday, as many as 4,500 employees worked at the facility.
On a typical day, more than 20 printer models might be undergoing testing, using designs and components from all over the world. All models are likely to become products, Novak says. Sometimes, HP partners build prototypes to be tested; eventually, the test units are manufactured, usually in various plants around the world. The Boise site hardware operation focuses on two main kinds of tests: life testing and regulatory testing.
Life Testing
HP LaserJet printers are used around the world, in a variety of conditions. The company’s printers must cope with varying temperature, humidity, and quality and type of electricity, as well as with more than 250 kinds of paper, ranging from wood based pulp paper in the U.S. to grass- and bamboo-based paper in Asian countries. Printers are put through a series of tests to ensure that printing quality is consistent under all sorts of scenarios, with all kinds of paper, throughout the expected life of the printer – and more.
For example, if a particular printer is designed to perform to a specific level, it might typically be tested for 1.5 times that. The printed test results are stored for later perusal and are, in some cases, scanned. Each printed sheet has its own UPC symbol to help track the results, which are stored in a relational database to allow for investigation in to any root cause failure modes. The printers need to be tested enough to result in statistically valid results with a designed confidence level, Novak says.
Printers are tested in at least four environments: high temperature, high humidity; low temperature, high humidity; high temperature, low humidity; and low temperature, low humidity.
The Boise facility has separate rooms built for each environment. Each room stores both the printers and their supplies, such as paper and toner, to enable them to acclimate to the environment. For example, paper stored in a humid environment accumulates moisture over time. In addition, because printers and their supplies are sometimes stored in different environments – an air-conditioned office for the printer but, perhaps, a hot or cold loading dock for the supplies – printers in each environment are tested with supplies from different environments, Novak says.
Regulatory Testing
In addition to its quality control testing, HP submits its printers to a variety of tests to satisfy the requirements of regulatory agencies around the world, similar to the Federal Communications Commission in the U.S. HP engineers track regulatory changes with representatives in the different countries to ensure that the tests are kept up-to-date.
HP is allowed to test its own products in its own facility, but must submit documentation of the tests – typically 100 days before releasing a product in a given country – and is audited periodically. Failure has two main aspects, Novak says. First, the company could be subject to large fines; however, the primary concern is to ensure customers are happy
Printers need to be tested with the different voltages, frequencies, and electrical quality available around the world, accounting for factors such as brownouts, power surges, and lightning strikes. Not only does HP want to ensure that the printers work under the various conditions, but the company also needs to ensure that its products can’t hurt the humans who are operating them.
In one particularly pertinent example, an engineer at the Boise facility was in the process of presenting material to substantiate why it was important to test for susceptibility to the impact of lightning strikes on the electrical grid when – coincidentally – lightning struck a tree outside the building, flickering the lights and creating a compelling argument for the addition of the test. A picture of the tree, with a fallen limb, is on one of the walls in the Boise facility as a souvenir.
Printers also need to be tested for radio frequency emissions. The company has a large separate room, incorporating a Faraday cage to shield out other types of radio frequencies, so that the only source of RF interference in the room would be the printer. A variety of antennae, pointed in different directions, test for emissions while the printer operates.
In addition, HP tests printers for susceptibility to electrostatic discharge. These tests are performed in yet another separate room, which is kept at higher humidity to help it simulate a standard office environment. Printers are “zapped” with a device to subject them to levels of electrostatic discharge that are common around the world. The testing that is performed subjects the products to various potential failure modes, ranging from “nondestructive” to “potentially destructive” to “destructive.”
Finally, the printers are subjected to a series of acoustic tests. The tests are performed in a soundproof room that is completely isolated, with multiple layers of foundation and springs to shield it from vibrations, such as that caused by passing truck traffic. A frame around the printer holds a series of microphones to record the sounds the printer makes while it’s running, this testing is performed to international specifications to ensure that results are repeatable.
But even if a printer complies with all the acoustic test regulations, people might still object to the sound it makes, Novak says. Consequently, the room also includes a head-shaped device that records the printer’s sounds as a human would hear them. Staff members can display the sound on a computer screen and break it into its various components to find the sounds and frequencies to which people might object. This process allows for a realistic assessment of acoustical performance, and the ability to simulate design changes, should HP determine that it’s worth the time and money to modify the acoustical performance.
Some customers like the sounds that their printers make, Novak says. Just as laptop and cell phone manufacturers learned they had to add clicky noises to keyboards because people wanted to hear the feedback, customers are familiar with printers making certain noises as the machinery operates. When customers don’t hear those sounds, they either resubmit the print job, or get up to check the printer to make sure the job printed – each of which adds inefficiency to the printing process, Novak says.
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