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Make e-Ink tablets an add-on for our phone/PDAs, not stand-alone


It's over 17 years since I first too a stab at e-Books, and while I was far too early, I must admit I had not predicted I would be that early. The market is now seeing a range of e-Ink based electronic book readers, such as the kindle, and some reasonable adoption. But I don't have one yet. But I do read e-books on my tiny phone screen. Why?

The phone has the huge advantage that it is always with me. It gives me a book any time I am caught waiting. On a train, in a doctor's office, there is always a way to catch up on reading. It's not ideal, and I don't use it to read at home in bed, but it's there. The tablets are all large, and for a good reading experience, people like them even larger. This means they are only there when you make deliberate plans to read, and pack them in your bag.

I'm not that thrilled with e-Ink yet, both for its low contrast and the annoying way it has to flash black in order to reset, causing a distracting delay when turning the page. There are ways to help that, but as yet it suffers. e-Ink also can't readily be used for annotation or interactive operation, so many devices will keep a strip of LCD for things like selecting from menus and the like. Many of the devices also waste a lot of space with a keyboard, and the Kindle includes a cellular radio in order to download books. e-Ink does have a huge advantage in battery life.

What makes sense to me instead would be a sheet (or two sheets, folded) of e-Ink with very little in the way of smarts inside the device. Instead, it would be designed so that a variety of cell phones could dock to the e-Ink sheet and provide the brains. Phones have different form factors, of course, and different connectors though almost all can do USB. (Though annoyingly only as a slave, but this can be kludged around.) It would be necessary to make small plastic holders for the different phone models which can mate to a mount on the book display, ideally connecting the data port at the same time. The tablet of course should be able to connect to a laptop via USB (this time as a slave) but do the same reading actions. The docking can also be, I am reminded by the commenters, done by bluetooth, with interesting consequences.

This has many large advantages:

  • Done right, this tablet is a fair bit cheaper. It has minimal brains inside, and no cell phone. In fact, for most people, it also does not include the cost of a cell phone data service. (I presume with the Kindle the cost of that is split between the unit and the book sales, but either way, you pay for it.)
  • The cell phone provides an interactive LCD screen to use with all the reader's interactive functions -- book buying, annotating etc.
  • The cell phone provides a data connection for downloading books, newspapers and web pages.
  • The cell phone provides a keyboard for the few times you use a keyboard on an e-Book reader
  • When you don't have your e-Ink tablet, you still have all your books, and can still order books.

The main thing the cell phone doesn't have is huge battery life. The truth is, however, that cell phones have excellent battery life if they are not turning on their screen or doing complex network apps. We do such activities of course, and they drain our batteries, but we expect that and thus charge regularly and carry more. I'm not too scared at the idea of not being able to read my books with the phone dead.

The tablet could also be used with a laptop, especially a netbook. Laptops can actually run for a very long time if you put them in a power conserving mode, turning off the screen and disks, possibly even suspending the CPU between complex operations.

However, there is no need to run it at all. While I described the tablet as being dumb, it takes very little smarts for it to let you page through a pre-rendered book that was fed to it by the phone or laptop. That can be done with a low power microcontroller. It just would not do any fancy interactive operations without turning on the phone or laptop. And indeed, for the plain reading of a single book, akin to what you can do with the paper version, it would be able to operate on its own.

Of course, the vendors would not want to support every phone. But they could cut a deal to let people use old supported phones (which are in plentiful supply as people recycle phones constantly) with a minimal books-only data plan similar to the plans they have cut for the dedicated devices. In the GSM world, they could offer a special SIM good only for book operations for use in an older phone of the class they do support. And they could also build a custom module that slots perfectly into the tablet with the cell modem, small LCD screen and keyboard for those who still want a stand-alone device.

This approach also allows you to upgrade your tablet and your phone independently.

As noted, I think a folding tablet makes a lot of sense. This is true for two reasons. First, you get more screen real estate in half the width of tablet. Secondly, with two e-Ink panels, you can play some tricks so that you flash-refresh the panel you aren't reading rather than the one you are finishing. While slightly distracting (depending how it's done) it means that when you want to switch to the next page, you do it with your eyes, with no delay. You have to push a button when you switch (even going from left to right though it's not apparently needed) so that the page you have fully finished refreshes while you are reading the next one. This could also be done with timings. Or even with a small camera watching your eyes, though I was trying to make the tablet dumber and this takes CPU and power right now. I can imagine other tricks that would work, such as how you hold the tablet (capacitive detection of your grip, or accelerometer detection of the angle.)

The tablet could also be built so the two pages of e-Ink are on the front and back. In this case it would not fold, though a slipcover would be a good idea. A "flip tablet" would display page 1 to you with page 2 on the back. To read page 2 you would physically flip it over. It would detect that of course, and change page 1 to page 3 when it was on the other side. This would mean the distraction of the flash-refresh would not be visible to you, which is a nice plus.

Cutely, the flip tablet could detect which direction you flip it. So if you flip it counter clockwise, you get the next page. If you flip it clockwise you get the previous page. Changing direction means you might briefly see the flash while you are flipping the unit but the UI seems pretty good to me. For those who don't like this interface, the unit could still hinge out in the middle to show both pages at once.

Bluetooth connection

Using bluetooth for the connection has a number of interesting consequences. It does use power, and does not allow exchange of power between the tablet and device, but it means you don't have to physically put the phone on the tablet at all. This may be a pain in some circumstances (needing two hands to do interactive things) but in other circumstances having a remote control to use to flip pages can be a real win.

I have found a very nice way to do e-reading is to have the pages displayed in front of you, at eye height, rather than down low in your hands. In particular, if you can mount your tablet on the top back of an airplane seat, it is much more comfortable than holding a book or tablet in your hands. The main downside is that the overhead light does not shine on the page there, so you need a backlight or LED book light. The ability to do remote control from your phone, in your rested hand would be great. Unfortunately they have the strange idea that they want to ban bluetooth on planes, though it poses no risk. They don't even like wires.

In the 90s I built a device for reading books on planes where I got a book holder (they do make those) and I rigged it to attach with velcro and hang from the back of the seat in front. In those days it was quite common to have velcro on the top of the seat. Combined with a book light, I found this to be way more comfortable than holding a book in my hands, and I read much more pleasantly. Today you might have to build it so that a plate wedges between the raised table and seatback and a rod sticks out to hold the tablet.

Or on some planes they could support e-books on the screen in the seatback, with the remote control that is in your armrest. Alas, they would indeed need to use bluetooth so your PDA could display the book on that screen. (In general, letting your PDA use the screen in front of you would be very nice. It's too sucky a resolution for laptops, since it must have been designed years ago in an era of sucky resolution. Today 1650 x 950 displays cost $100.


A physical connection isn't necessary -- smart phones come with Bluetooth, and that's more than enough bandwidth to implement a text + still graphic connection to the eInk screen.

I was going to post the same thought.

I have a PRS-505 and have been whining in various places that a usable cellphone as part of the deal would make me happier. I actually sit in the other camp - if I don't need to hold it to my ear I'm not too fussed about size and weight. But I don't wear a suit and usually carry stuff like a D lock so the idea of a PRS-505 sized device that's 15mm thick with a giant battery and a bluetooth headset + phone ability appeals a lot. I carry an external battery/charging device anyway so I can pump my 27 random electronic devices up as I travel - making that smart would be an obvious step.

But flipping that makes more sense frm a market size perspective - lots of people already own smartphones and if they could support a bluetooth external display that would rock. Not need to force eInk, there's more display technologies on the way. Just how much dumber it needs to be than a PRS-300 is open to question - it might be easier to just add bluetooth to a basic eInk device so you could sell them independently. Possibly even with a "free" bluetooth USB dongle to make the usual connection power + wireless data.

Sorry, I was thinking about it but forgot to mention it. No exchange of power possible, but it also is no longer necessary for the phone to be mounted on the tablet at all, though you might still want it. This turns out to allow something quite useful, which is remote control of the page flip.

I have found it to be quite nice, on an airplane, to mount my book on the top of the seat in front of me, hanging down in a book holder at eye height. I built a tool to do this long ago, which I attached to the top of the seat with velcro -- there used to be a velcro cloth on the back of seats on most planes. Another way to attach it is a mount which can be crunched between the tray and seatback that sticks up and holds the reader.

You need to illuminate the book or reader when you do this, as the overhead light does not shine on it. But the remote control in your hand that would come from the cell phone control is a very pleasant reading environment.

This is really an excellent idea. It would be great to just have such an e-ink screen and control it with my netbook. If a company sold such devices I would definitely buy one. Actually, I searched for something like that in google but only found your blog :-) The ides is born and thus it shoud not take too long that something like this will be available, I hope :-)

I was googling for the same product. I can't wait to see if someone makes something like this. I'd get one in a heart beat.

It would work great with some kind of software that does a print screen conversion. Then I can print a recipe or instructions from my laptop and take them with me instead of writing them down on a piece of paper then 'recycling' it two minutes later.

Check out the Boogie Board LCD writing tablet by Improv Electronics An interesting product but you have to physically write on it with a stylus. Perhaps that company would have the capabilities of making said product above. Maybe if a bunch of people contacted them with an interest in that product something might happen!


I kind of disagree with the opinion here that the "thing", the display does not need a proper "computer" or "brain" inside. It needs one, and there is only little way around that. New mobile CPUs - as they are used in mobile phones - are actually well-suited for building an e-reader, and the hardware platforms are not too different to what you find in e-readers. The "thing" needs some kind of OS unless it is nothing but a passive screen that only needs rudimentary functionality.

I agree, it would be nice to have an e-ink screen - technically an external monitor, that would run on an existing netbook and probably acts as both a pointing device (e.g. wacom pad built in) and a monitor (SVGA etc.). Such a device could run on USB power and one could turn off the laptop's backlight. With the more recent CPU's, this could be quite a useful device, eliminating the need of a printer when you want to read PDF's outside or on the balcony. Such a device - however - could not work with some "old" cellular phone as the phone itself does not have the interfaces or the graphics processor to deal with such a large screen. It would basically be some sort of 2nd monitor - maybe touch monitor - for a laptop or netbook. Needing no battery and only some tiny integrated circuits it could be light as a piece of cardboard.

As to what exists already: There are indeed some hybrids of netbooks and e-ink readers on the market, and the most prominent ones are supposed to run android linux. They are called dualbook edge (equally sized laptop screen and an e-ink screen) and alex (one bigger e-ink screen and a smaller backlit laptop screen). The philisophy remains the same: use the laptop screen for "computer work" i.e. getting and loading the stuff to read, and read / annontate on the e-ink display.

These 2 machines currently have one severe problem: There is so far no fully fledged linux distro for ARM CPUs (as used in most of these mobile devices) that supports adobe flash natively (due to Adobe's lack to develop their players for ARM properly (?)) which in turn keeps companies from building ARM powered netbooks with an easy-to-use distro (e.g. debian, ubuntu) that comes with tons of good software. Android is for ARM, however android does not go too well with X11, meaning that X11 software won't run without hacks (currently). Android is primarily still a phone OS and not a laptop OS, so there is a lack of desktop software for this OS.

The calculation is simple: We can have the device, but the OS we want does not yet exist: We want a mobile reader OS distribution that people are happy with. Maybe android is the way to go - at least there is a lot of potential in it. Maybe it's good to go for something new - skipping X11. Maybe it's good to set on something that "kind of" works - like X11. There are pros and cons on both sides.

Back to the original question: The hardware is here already - but the software isn't. And I guess it won't be until laptops, smartphones and readers don't use the same platform. They could and I think they will converge at some point. Just a matter of screen size in the end - all on top of a small linux box beneath it. If it boils down to that, compatibility is not an issue anymore. These boxes have been networked around the globe for a long time. Data exchange is definitely not the issue here. Just choose a solid OS core, be it linux, bsd or another *X derivate.

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