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Selecting a Printer For Mobile Computing

Written by Tony Revis

In recent years, mobile computing systems have fast become an integral part of law enforcement. Mobile computing succeeds in alleviating much of the legwork and inefficiency that can result from hand-written methods.

Of course, mobile computing is rarely limited to simple data collection. These applications often require some type of print capability while in the field. The need for printing varies.

On the one hand, simple output for a traffic citation requires plain text. Even a credit card receipt is fairly simple to print. In other applications such as complex reports, service records, and machine-readable receipts, more complicated output is required.

It is clear that different applications have different requirements and needs, thus there are many factors to consider when choosing a portable printer. Unfortunately, selection of a portable printer that will optimize performance requires more effort than conducting a simple Web search.

At a recent Thermal and Ink Jet printing conference, Endre D. Vargha, president of Global Management Resources, provided some guidelines for portable printer design that are appropriate for printer selection. According to Vargha, the primary application affects a number of variables, including battery capacity and life, maximum paper roll capacity, and system integration and connectivity.

Beyond these variables are universal capabilities that customers should look for regardless of application. These include printer reliability, ease of use, compact size, and light weight. It is important to take all these guidelines into account when selecting a portable printer.

Printing Software

Today, most mobile computers employ Windows CE or some derivative of the operating system. Palm is still used but to a much lesser extent, and Symbian seems to reside in the domain of smart phones. Windows XP or an equivalent system is used with most ruggedized notebooks and pen pads.

Unless a custom application has been specifically designed for the Pocket PC to provide printing capability, there are a few things to consider when selecting software. First, Microsoft does not provide much in the way of direct print capabilities. The vast majority of software offered by Microsoft is best suited for desktop computers and print.

This is not very useful for the people who work in untraditional office environments, i.e., as having to move from place to place, using portable information devices. Essentially, there is no direct way to print from Pocket Word, Pocket Excel, or Pocket Internet Explorer in the basic Pocket PC platform as provided by Microsoft.

Fortunately, companies like Fieldsoftware (www.fieldsoftware.com) and Bachmann Software (www.bachmannsoftware.com) provide excellent print utilities that a developer can embed into the application. A number of printer companies may even provide utilities either under a negotiated supplier license they or for a special price, which gives added incentive to choose this particular software.

Interface between the Pocket PC and the printer

Beyond the software being implemented on the mobile computing device, there are many options to consider when deciding how to connect computer to printer. In the early days of mobile computing, the only choice was serial cable, which was prone to breaking.

A breakthrough in wireless communication for personal area networks came with the advent of Infrared communications and the establishment of a universal standard, IrDA. Many of these systems are used extensively outdoors without being adversely affected by sunlight.

Essentially, a wireless connection of this type needs a direct line of sight between the Pocket PC and the printer from a distance between about 18 inches and 4 feet. Properly equipped with double cones and the ability to handle temporary disconnects in communication, the robustness of this interface and its ability to handle two-way communication has yet to be matched by competitive products.

Until recently, most Pocket PCs came with built-in infrared ports corresponding to the IrDA standard, and most (but not all) portable printers had the capability to be IrDA compliant.

Similarly, wireless solutions such as Bluetooth and WiFi (802.11b) have recently been made available in most handheld computers today. An important thing to note though that is often overlooked though is that Bluetooth cannot be added to a WiFi network without an interface card.

Frequently, handheld computer companies that focus on warehousing and retail assume that WiFi networks are available and make sense for all printers, both portable and desktop to communicate with the network. In actuality, WiFi may be ill-suited for outdoor portable applications.

Output Size

Once printing software and interface have been secured, one of the biggest factors to consider is the size of the output needed. Essentially, portable printers come in two basic categories. First, there are small format printers described in three media widths: 2-inch (58 mm), 3-inch (80 mm), or 4-inch (112 mm). Selection of the print output between these three widths is a function of the application.

Reports, for example, are often on the larger widths, while traffic and parking tickets are on the smaller end of the spectrum. Also, an organization looking to include its logo on all documents will be able to do so, but it should choose 4 inch over 3 inch for reports or invoices and 3 inch over 2 inch for tickets or receipts in a bid to have a sharper, more impressive looking logo.

Beyond the small format printers are page printers, which generally implement a standard letter size (or A4 page) and have been built around 80-column output.

The receipts and tickets generated by small format printers require limited amounts of information on the output. Page printers would be used in applications that require larger amounts of printed information, particularly where multiple copies were required to be printed at the same time.

Historically, page printers have been dot matrix types that are large, heavy, and slow printing, not to mention hardly portable. Frequently, these printers are truck mounted. However, 4-inch wide direct thermal printers now have the ability to print 80 column output, and are thus beginning to replace the larger dot matrix page printers. These newer printers can print a receipt four times quicker than an 8-inch dot matrix printer could print a single page with three carbon copies.

Output Type

Another consideration regarding output type is the printing technology that is used to produce the output. Portable printers tend to fall in three categories – either direct thermal, dot matrix or, to a lesser extent, ink jet.

Direct thermal is a printing technology that does not require a separate ink cartridge. With direct thermal, a heat sensitive layer is embedded in the media and is activated by the printer’s print-head when the printing elements are heated. For portable printing, direct thermal is typically used in small format printers. Recent improvement in thermal paper manufacturing has added extended archival storage, improved performance in exposed environmental conditions and improved sensitivity, so less energy is needed for “burning” the image.

Dot matrix printers make use of an impact between a “hammer” and the paper with a ribbon placed between the two. The resolution of the print and the speed of printing are much less than for other printing technologies.

Ink jet printing, on the other hand, deposits ink from the print-head to the media and can use standard paper for output. One of the benefits of ink jet is that it is capable of printing full color output, where direct thermal is limited to one color (typically black). Ink jet printing is rarely used in small format printers and is more commonly found in page printers. Operating temperature range is usually much less than for direct thermal printers.

For output needs that are short term in nature, direct thermal can prove to be an effective solution, providing high quality output with almost no maintenance issues. However, for page sized output with the desired option of printing in full color, ink jet is a better choice.

Print Speed

Another factor to consider is the speed at which the printer can deliver the needed output. Depending on the printer, print speed can be rated in a number of ways—by characters per second, lines per second, inches per second, or pages per minute. However, manufacturers’ claims are less than precise, thus the best thing for a department to do is to conduct some comparisons in a controlled test.

Remember, it is important to consider the total time to print from the moment the print button is selected. Text printing requires less time than graphics printing. Some printers allow constant graphics files such as logos to be stored in printer memory so they do not have to be sent from the computer every time. Additionally, it is possible to switch between graphics and text printing within a ticket to minimize total print time and to produce the best looking image.

Ease of paper changing

Customers should look for the latest technologies that offer a drop in load for the paper roll rather than threading paper through the roller. In fast-paced, high output jobs like law enforcement and mass transit, this system (often called “clamshell” design) allows the user to change the paper roll with efficiency and ease while in the field.

Battery Life

As is the case with most portable electronic devices, battery power needs to be taken into account when choosing the right portable printer to meet the needs of an application. With portable printers, there is a direct correlation between battery life and the number of characters printed. If an application requires either many small print jobs or a lesser number of more extensive print jobs, care should be taken to choose the appropriate printer that has enough power to meet the need.

As is the case with an application such as traffic ticketing, the longer a printer can operate between battery recharges, the better. Lithium Ion technology is most frequently employed today for longer battery life because it overcomes many of the issues of memory and of the need for conditioning in prior technologies.

For example, this technology is less susceptible to voltage depression and handles partial discharge and recharging much better than earlier technologies. When choosing a battery pack, examine the total voltage available and the capacity of the battery. A voltage rate of 7.4 (2 cells) is preferred, and capacity in excess of 2 amps is now the norm. With power like that, a significant amount of work can be outputted on a single charge.

Regardless of capacity, most portable printers have a rechargeable battery pack, so the printer can be easily recharged between uses either within the printer itself or in a separate recharge station.

Product Certification

Beyond simply selecting a mobile printer that maximizes efficiency and productivity, it is important for customers to recognize the ever-changing regulatory landscape, which is placing increasing demands on manufacturers. Nearly all printer companies have FCC and CE certification in place for emissions and immunity. Look for printers with IEC 60950 certification.

At the same time, many applications require extensive use outdoors, often in robust environments. IEC 68 certification is available for temperature range, humidity, shock and vibration, and drop. Also, there exist IP ratings for dust and moisture intrusion that should be taken into account to ensure the performance of the printer.

Check the warranty provisions carefully. At least a full 12 months should be offered and should guarantee all parts except consumables. For certain manufacturers, extended programs are available.

The addition of a mobile printing capability can add a necessary component to many law enforcement functions. With careful consideration given to the mobile printer used for the project, the printer can be more easily matched to any needs.

Tony Revis is the general manager of Extech Data Systems (www.extech.com), a division of Extech Instruments, a leading developer of portable printers for applications centered around mobile information and remote transactions. He may be reached at tony.revis@extech.com.

Published in Law and Order, Jun 2006

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