Multifunction Printers

Multifunction Printers and Scanning

Multifunction printers combine a computer printer and a scanner in one unit. An immediate benefit of this is that the printer can act as a copier. With the addition of a modem it can also act as a fax machine. And if the printer has a network connection and a user-friendly screen it can also be part of a document management system scanning paper to files and reproducing it as needed.

Scanners used to be expensive items and as stand-alone units they still can be. The heart of a scanner is similar to the read head of a fax however, and just as fax machines became cheap scanners can be. A printer already has the plastic body, the motor drive voltages, processor, memory and communication interface. All that is needed to make a digital copier from a printer is to add the scanner head, a sheet of glass, some lenses and an extra motor. Converting the page image into a bitmap then printing the bitmap gives a copier.

There are some complexities. Ordinary photocopiers don't handle photos very well because the mechanism doesn't have much greyscale. In principle a digital copier can be better. If the printer is used with higher resolution than the scanner it can use a dither-pattern to deal with photographic grey-scales. Alternatively if the scanner is used with a higher resolution than the printer then it can be used for enlargement - from 4x6inch photo to A4 for instance.

Colour copying needn't be expensive with a multifunction printer. Photocopiers that could handle colour were phenomenally expensive until the mid 1990s (£15,000 plus). A multifunction copier with an inkjet printer inside needn't be expensive to buy. Inkjet cartridges can be expensive of course, but not compared with photographic prints.

A digital multifunction device can be flexible in ways no ordinary copier can. For instance page images can be stored onto or read from USB pens or SD memory cards. Images from a digital camera can be printed directly from SD cards. Images can also be downloaded from a camera using a technology called PictBridge. Using the scanner old photos can be scanned and retouched, although doing this job well needs an especially high resolution scanner to avoid losing any detail from a photographic original.

One of the advantages of a multifunction printer over a copier is that it can be attached to a computer. Some cheap multifunction devices actually have to be attached to a computer because it provides them with processing power. The connection is optional with rather more capable devices that have their own processor, memory and built in software. PictBridge printers can control a camera using a USB cable.

There are two normal methods used to connect a multifunction device to a computer. The simplest is USB and the most flexible but more troublesome method is via Ethernet.

USB (Universal Serial Bus) is the commonplace way of attaching nearby gadgets to a computer. The commonest examples are data pens. For the duration of the connection the gadget actually becomes part of the computer it is attached to. Most operating systems have ways to share printers on a network, so the multifunction printer can be made available to others sharing the local network. It might not be possible to share the scanner in the same way.Ethernet connections share the printer directly, without needing a connection to a local computer. A network connection is more expensive for the printer manufacturer because the printer needs a processor powerful enough to support networking.

Pull scanning - "TWAIN compliant scanning"

In pull scanning the user places a document on the scanner and then uses one of the applications on their computer to get it. In the program there will be an insert picture or similar command that can access the scanner. If the printer-scanner are directly plugged into the computer using USB there isn't much problem about how to control it. The commands it needs to send and the data expected are set out in the TWAIN standard. TWAIN was developed by scanner makers and software producers as a common standard. Microsoft have a standard called Windows Image Acquisition (WIA)

Recent systems can also find a scanner over a network. The TWAIN commands and responses are directed across the network.

To the user "pull scanning" across a network is no different from using a scanner attached directly to their computer using USB. However if the scanner is shared scanning a document might need two trips, one to put the document on the scanner and another to retrieve it.Technically there is a big difference between a local USB scanner and pull-scanning because a network exchange is needed.

Push scanning - "Canon Universal Send"

In push scanning the user places a document on the scanner then selects the scan operation using a button on the scanner or on the multifunction printer control panel. The printer will respond by asking where to send the document, which can be an e-mail address, or any kind of file-server. If a file-server is used it will typically be a Windows file-share but in a more complicated IT environment an FTP server might be preferred.

The document destination is selected using a drop down list from the copier address book or by typing one in. The user presses start and the scanner does the work of copying the file to that location. At the end the user picks up the document and returns to their desk, and the document appears in their mail or in a file. From the user viewpoint push scanning is neat because a scan involves one trip. Push scanning might also suit circumstances where all mail is to be scanned - there is no individual recipient the workflow just records all mail.

A keyboard might be useful and some printers have one, although it's often a rather curious device. If a multifunction device is going to have heavy use the menus need to work efficiently.

Push scanning is technically moderately complex but may be preferable because all the components are standard. The scanner produces a standard document - usually either TIFF, JPEG, BMP or PDF. This document is sent to the destination using standard file handling protocols like SMB or FTP. Because push-scanning components are highly standardised it should work in mixed IT environments using Windows, Apple and Linux machines.

Where great volumes of paper are to be processed a digital sender with its purpose designed processes might be a better choice.

Scan to Memory

Multifunction devices with memory card slots or USB host ports can often scan to a local memory device as well. The user gives the right commands and the scanner puts the documents on a flash pen. If there's a lot of scanning to be done and the menu arrangement is suitable this might be particularly useful because there is no need for computer or network connection.

Some cheap personal scanners intended to be used with PCs look and behave like push scanners. They have a few keys which start the scan and pop up an application on the local PC. This isn't the same because the PC and not the scanner is doing the work.