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.