A couple of steps down from the Editors’ Choice DSmobile DS-940DW and a step down from the DS-740D, the Brother DSmobile DS-640 ($109.99) is a manual-feed portable document scanner designed for use on the road in conjunction with a laptop PC. However, for the $20 list-price difference between it and the DS-740D, you give up automatic two-sided scanning and a few other features, not to mention the ton of options you would get by stepping up to the PCMag favorite DS-940DW (which lists for $70 more than the DS-640). Even so, if all you need is to scan short one- or two-page documents to a laptop or desktop, the DS-640 does that relatively quickly and with respectable accuracy.
Compact, Light, and Simple
At 1.5 by 2.0 by 11.9 inches (HWD) and weighing slightly over a pound, the DS-640 is the smallest and lightest of the three Brother DSmobile models mentioned here. When it comes to compact and featherweight, though, Epson’s similarly priced (to the DS-640, that is) DS-70 Portable Document Scanner is slightly smaller still and weighs about half as much as this lowest-priced DSmobile model. And the Epson supports automatic two-sided scanning, which, again, the DS-640 does not. In other words, to scan two-sided pages, you’ll have to run them through the device twice.
Also missing, but available on the DS-940DW and DS-740D models, is a feature Brother calls Desk Saving Design, or DSD. DSD consists of a cover that you open at the back of the scanner that directs the output upward, instead of behind the device, thereby minimizing the required operating area by about 11 inches, depending on what you’re scanning.
Like the DS-740D, the DS-640 has a very limited set of physical controls, consisting only of a Start/Stop toggle and a status indicator. Both are located on the top right edge of the device.
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You’ll find the USB 3.0 port on the right edge of the scanner, just below the controls. The drawback to limiting a device like this to USB connectivity is, of course, that you can’t connect to it with most mobile devices, which limits your scanning primarily to laptops and desktop PCs (and some tablets).
The next model up, the DS-740D, supports only USB, too, as does the Epson DS-70, but the DS-940DW also supports wireless connectivity, allowing you to scan to handheld devices and from networked PCs.
Brother rates the DS-640's maximum duty cycle at 100 scans daily. Its maximum optical resolution is 600dpi, with an interpolated 1,200dpi. The maximum document size is 8.5 by 72 inches, and the minimum size is 2 by 3.4 inches. The smallest and largest plastic card sizes you can scan are 2.05 and 3.4 inches square, respectively.
Seeking: Software for Business-Card Archiving
The DS-640’s software bundle is identical to that of the DS-740D. You get the standard TWAIN and WIA drivers for scanning into programs that support direct scanning, as well as the latest ICA drivers for Windows and SANE drivers for Mac. The bundle also includes Nuance PaperPort SE with OCR, Power PDF, Brother's iPrint&Scan (for Windows, macOS, iOS, and Android), and Presto PageManager with OCR for Mac. Supported cloud sites are Dropbox, Evernote, Google Drive, and OneDrive.
PaperPort SE provides a scanner interface and basic document management, and Power PDF lets you create and edit PDFs. iPrint&Scan is Brother's cross-platform driver, and Presto PageManager provides functionality similar to PaperPort SE, but for macOS.
Also like the DS-740D, the bundle doesn’t include a business-card scanning and archiving program, which is a common function for a portable scanner. To get that functionality, you’ll have to step up to the DSmobile DS-940DW, which comes with both Presto BizCard and BR-Receipts for scanning and archiving financial documents. Or you can purchase a card archiving app online. BizCard by itself runs about $70, though.
Scanning and Accuracy
Since, with portable scanners, how fast you can feed each page in succession greatly affects the device’s overall scanning speed, the speeds you get from the DS-640 may vary from mine. Brother rates it at 16 pages per minute (ppm). Between the scanner, its software, and me, I was able to get it to scan and save our 25-page simplex (single-sided) text document to image PDF at the rate of 13.1ppm.
That’s slightly slower than what I got from both the DS-740D and DS-940DW. It’s also much faster, by about 5ppm, than Epson’s DS-70. Keep in mind that the DS-640 can’t do two-sided scans, so those scores aren’t reported here.
When scanning these same documents to the more versatile searchable PDF format, the DS-640's performance was about the same as it was for image PDF. As I’ve said before, these little portables don’t typically scan fast enough to bog down the optical character recognition (OCR) software’s conversion from scanned to editable text.
As for accuracy, the DS-640's OCR function converted our scanned pages to editable text, error-free, down to 5 points for our Arial font test page and down to 6 points for our Times New Roman page, which almost matched its two more expensive siblings. They were accurate down to 5 points without mistakes with both fonts, which is the best score among the other portables mentioned here. Both the Epson DS-70 and its sibling, the Editors’ Choice DS-80W (which also supports Wi-Fi), managed scans down to 6 points without mistakes on both of our test font pages.
All these scores are more than passable for most scanning applications. As I said in my DS-740D review, nowadays OCR has become a mature technology. Accuracy, whether it’s an under-$200 portable scanner or a $1,000 desktop screamer, isn't really an issue anymore.
Simple and Economical
Compared to its two DSmobile siblings, the DS-640 is more of a niche portable document scanner. It’s designed primarily for connecting to a laptop on the road, and only for scanning one-sided documents such as, say, applications or sales receipts. It would make a good business-card scanning and archiving solution, too, if you weren’t forced to buy that software separately. It’s priced the same as the Epson DS-70, which does have the ability to scan two-sided pages in one pass.
If that’s what you need, also consider the Epson. The DS-640 is faster and a little more accurate, though, making it a decent solution for scanning short documents, if clearly overshadowed by the DS-940DW.
The economical Brother DSmobile DS-640 scans quickly and accurately, but it lacks single-pass duplex scanning, making it an occasional-use model for thrifty shoppers.
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Sign up for other newslettersAbout William Harrel
Former Contributing Editor
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