Having two displays for a desktop or laptop computer can be a real boon for productivity, giving you much more space to spread out your cramped documents, spreadsheets and web browsers. If you own an Android tablet, why not put it to work as your secondary screen? Follow this handy guide and all those windows piled up on your display will finally see the light of day.
While monitors aren't prohibitively expensive, an Android tablet is a perfect substitute for a second display if you own one... or even a third display if you already have an extra monitor and harbour fantasies of working in NASA mission control.
In order to set up an Android tablet as a secondary display, you have to download an app. There are a good many apps available that turn a tablet into an additional screen. Two of the most popular are iDisplay by Shape and ScreenSlider by Redfly.
ScreenSlider is an Android/Windows-only app, while iDisplay supports Android, Windows, iOS and Mac. Air Display is another alternative. I tried to find a free app that turned a tablet into a secondary display but had no luck (if you spot one, share it in the comments below). I've chosen iDisplay for this guide as it has more options for different platforms.
What you need
You need a compatible tablet running Android 3.01 or newer and your computer should be running Windows XP, Vista or 7 (32-bit or 64-bit). For Mac, OS X Leopard or newer is required. You also need a wireless network as this will be used to connect the tablet to the computer.
1. Installing iDisplay and opening it on the tablet
Installing the app is as easy as tapping the Google Play icon on your tablet and searching for the app or following this link. The app isn't free (it costs £3.99), and will require you to set up a Google Play account. This will be linked to your Google account so you only need to enter your credit card details once.
When this is done, the next thing to do is download the app and open it. You will be presented with one option -- connect via USB. If you want to connect over Wi-Fi, you have to download a client for your PC or Mac (see step 2), before this option appears on the Android tablet. If connecting via Wi-Fi, you have to make sure both tablet and PC are connected to the same network.
2. Installing the companion client on your PC
The client can be downloaded from the vendor's website, which has clients for both Windows and Mac. For the purposes of this article, we are going to focus mainly on the Windows version (further down this article you can see that the Mac version is by and large the same).
Once downloaded, you can install the software in just a few clicks. While installing, it warns you that it will also install a video driver and asks you to click OK to install this driver. The installation also requires you to reboot the machine.
3. Starting the companion client and pairing it with the tablet
Once rebooted, you can click on the icon to start up iDisplay. A Windows Firewall exception request appears, and after allowing the exception and joining both devices to the same wireless network, we can make a connection between the tablet and the desktop.
A dialogue box pops up and here you can either allow iDisplay to connect to the tablet once only, always allow or deny. I chose always allow. There is also an option to connect the tablet to the PC via USB (disclosure: I tried and failed to get a USB connection working with the software for no discernible reason).
On the tablet, a list of devices is shown on the app, which the tablet can pair with. Tapping on the device you want to pair with will then connect the tablet to the computer.
4. Optimising and configuring the tablet display
After connecting, the real trick now is to make the display size work for you. In the settings page (the cog icon in the top right-hand corner of the connection page in the iDisplay app on your tablet), you can choose from four different resolutions. Counter-intuitively, with the small size of the tablet, a bigger resolution works better. (Choosing a smaller resolution on this page may seem like the logical choice, but this leads to the tablet displaying windows with enormous text and outsized pictures.)
The Windows client can start automatically when Windows starts. You can also right-click on the system tray icon to quit the client. Right-clicking on the system tray brings up the 'Display Arrangement' option. Here you can select where you want the tablet to be relative to the main display. This can either be to the left or right, but with a bit of coaxing you can place the tablet above or below the main display, or even between the main display and a second external monitor.
Using iDisplay with a Mac
The tablet app will work with clients on both Windows and Mac. Installing on a Mac is similar to Windows. Again, you have to allow the client to connect with the tablet app before you can pair the two.
With the client on Mac, while much of the functionality is the same, the choice of display arrangement is found in System Preferences. Again, the tablet display can be arranged to be anywhere next to the main display.
Shortcomings
Performance of the tablet display can be variable, but this is down to the speed of the wireless network (a faster network will increase the responsiveness of the display), processor speeds and graphics capabilities. I found that it was the speed of the network that had the biggest bearing on the responsiveness of the app display, by far.
Another problem I found was when, for no reason, the app lost connection to the PC, resulting in numerous reconnections to pair the tablet with the computer (this happened both with PC and Mac). While reconnection is a simple tap, the resulting lost connection can mean having windows appearing back on the main display after they've been moved to the second display. Luckily, upon reconnection the app remembers which windows appeared on the tablet display.
Also, the performance of what you have running in the tablet display will vary considerably. Chrome works well on the tablet display, while Firefox did not refresh much (if at all) and could not render the page most of the time. Calculator ran well, as did Word. Internet Explorer did not render properly and I found that video also lagged and dropped frames.
But if you can live with the glitches, having widgets, chat windows and the inbox on a second display can be a boon and will lengthen the shelf life of your tablet once it starts to show its age.
