I stumbled across the article about the ThunderScan in about 2012 when looking for info about ImageWriter II upgrades, and have been slightly obsessed ever since. It's such a brilliant idea - a higher resolution scanner, that was far lower in cost than its competitors, achieved by reusing the paper transport that most customers already had.
I'm lucky enough to own two working ThunderScans now (and one third one that I needed the software driver from). They work exactly as advertised, and it's a joy to see them zip across the page, digitising line by line.
The software by Hertzfeld is another joy to use. The scrolling, which Hertzfeld calls "inertial scrolling" in that article, is now familiar to us all who have used touchscreen devices. It's funny to think that the feature that wowed so many at the 2007 iPhone launch actually existed all the way back in 1984, designed by one of the key creators of the Macintosh.
I wish there were more creative hacks like this - I just know that if a company tried to do something similar today, the printer manufacturer would instantly roll out an update to break this functionality.
I wonder why the system didn't caught on and why it's not used today by manufacturers of multi-functional printers. Seems like a huge opportunity to use the existing paper handling mechanism - with an autofeeder, a feature most flatbeds lack! - and get a more compact device.
The entire device consists of a single, cheap CMOS image sensor, a lens focused at a fixed distance and a RGB led. Everything else, stitching the resulting scanbands, correcting for mechanical and optical distortions, etc. is all in software. The native optical resolution you could expect from, say, a 1080x720 px sensor would be something like 2400 DPI.
The only downside i can think is that you can't scan IDs, passports etc. and the location near the inkjet head tends to get dirty.
Canon tried with some Bubblejet printers, like BJC4300. It needed three passes per line (R,G,B) slow and lower quality.
I think also it was expensive, since I wanted to get it, but failed to find it.
OTOH, a 10 year old HP multifunction can scan things at 600DPI in acceptable quality and detail, in a very reasonable amount of time.
If you want to go compact, but fast, there's Kodak Alaris' "i" series scanners which can scan both sides at the same time. Scan time is ~4 seconds per double sided A5 page at 600DPI, and less than a second for ~200 DPI.
Interesting. The drawbacks you describe seem to be limitations of the sensor and image processing technology available almost 30 years ago.
For example, my Epson inkjet printer can do about 10ppm at it's lowest print quality, so it can mechanically move and scan a page against the printhead every 6 seconds; a 1Mpx sensor with a 60Hz frame rate will generate 360Mpx in 6 seconds. Even if you throw away 50% of the data (overlap areas, next page load, motion or optical blur at the edges etc.), that's still enough data for a ~1400 dpi raw resolution of an A4 page at the fastest speed. If you are willing to go slower, the resolutions the system could achieve seem outside the range of any flatbed.
Of course, you would need e very beefy image processor to handle the multiple Gbps raw video data and process in real time down to the final scan image, but the actual corrections seem very achievable with modern algorithms.
Outside of the cost of the image processor, another showstopper I can see is motion blur on the sensor, stopping the heavy printhead from its inertia, so that you can have a still image, will kill your total scan speed. But perhaps you can just pulse the LED, or a gas discharge lamp, and impress the sensor with near instantaneous flashes of light.
I had a Canon scan cartridge around 1999. It was slow, but worse, it was very finicky about the printer cable being used - which at the time could be very expensive and were not included.
It worked, but there was a clear linear pattern across scans. It worked for some things, but wasn’t the best for photos.
I have an HP All In One and I was quite disappointed when I first used it to digitize photos. It's nowhere near 600DPI. The quality I got from the scanner was worse than taking a picture with my phone!
Of course taking a picture with the phone requires good lighting and the photos you want to scan need to be flat.
You can get cheap, compact scanners that just feed the paper through instead of laying it on a flat pane of glass. Almost the same thing except not multifunctional and with a page width sensor instead of one that would scan back and forth.
It precludes many of the advantages of a flatbed scanner (such as scanning book pages without requiring removal of the pages), which existed at the same time as the Thunderscan. Things like hand scanners established themselves at the low-end by the early 90s.
People today (or maybe just businesses) seem thoroughly uninterested in interoperability or upgradability.
It's a fantastic ideal for nerds who like to repair and upgrade and Frankenstein tech bits into new shapes, but I'm not sure I've ever met a normal person who was interested in adding a feature to an existing widget instead of buying a new widget.
I'm absolutely certain this is because it's less profitable for businesses to offer upgradable or interoperable parts.
I'm lucky enough to own two working ThunderScans now (and one third one that I needed the software driver from). They work exactly as advertised, and it's a joy to see them zip across the page, digitising line by line.
The software by Hertzfeld is another joy to use. The scrolling, which Hertzfeld calls "inertial scrolling" in that article, is now familiar to us all who have used touchscreen devices. It's funny to think that the feature that wowed so many at the 2007 iPhone launch actually existed all the way back in 1984, designed by one of the key creators of the Macintosh.
I wish there were more creative hacks like this - I just know that if a company tried to do something similar today, the printer manufacturer would instantly roll out an update to break this functionality.