您是否碰巧在房子周围放置了一个不再使用的额外 iPad？在最终升级到iPad Air 2(iPad Air 2)之前，我保留了我的 iPad 2 多年，这意味着 iPad 2 只是坐在办公桌抽屉里(desk drawer)。但是，为什么要浪费一个非常好的 iPad，对吧？
我之前写过如何在Windows中设置双显示器，但这需要第二台显示器。幸运的是，借助一些巧妙的软件，您可以将旧 iPad（第 2、第 3 或第 4 代）、iPad Airs（1 和 2）或 iPad Pro(Pros)用作Mac 或 Windows PC(Mac or Windows PC)的第二个屏幕或第二个显示器。这基本上涉及在 iPad 和计算机上安装应用程序，然后使用闪电电缆(lightning cable)或 30 针电缆（坞站连接器(dock connector)）直接连接两者。
我最喜欢的应用程序也是我唯一推荐的应用程序是Duet Display。还有其他选项，例如Air Display 和 iDisplay(Air Display and iDisplay)，但两者的成本大致相同，而且效果差强人意。电脑和 iPad 之间的直接连接使体验几乎没有延迟，这在使用第二个屏幕时非常重要。尝试通过WiFi（即Air Display）进行此操作非常缓慢，而且不是一个好的实现。
二重奏显示
同样值得注意的是，Duet Display是由前 Apple 工程师创建的，这可能是它在 iPad 和(Duet Display)Mac 上(Macs)运行良好的主要原因之一。该应用程序的价格为 16 美元，如果您查看App Store中大多数应用程序的价格，这将是非常昂贵的，但我认为这更像是一个标准的Windows 或 Mac 程序(Windows or Mac program)。
进行所有设置(everything setup)非常简单，不需要任何类型的帐户创建或(account creation or anything)类似的东西。首先(First)，继续将应用程序下载到您的 iPad 上。请注意，您也可以将 iPhone 用作第二个屏幕，但在我的测试中它有点没用。您肯定需要更大的屏幕才能正常工作。
Duet Display – iTunes
当您打开应用程序时，您会收到一些非常简单的说明，告诉您先将软件下载到您的计算机上。
点击知道( Got It)了，您会看到一个屏幕，要求您将 iPad 连接到计算机。然而，在我们这样做之前，我们需要先在PC 或 Mac(PC or Mac)上安装软件。
继续将PC 或 Mac 程序(PC or Mac program)下载到您的计算机上并安装它。在Mac上，您将在启动时获得一个圆滑的矩形安装屏幕。(rectangular install screen)
单击“开始(Start)”链接，选中“我同意( I Agree)” ，然后在下一个屏幕上单击“授权并安装”。(Authorize and Install)
安装完成后，系统会要求您重新启动计算机。继续做吧。重新登录后，您应该会看到一个最终屏幕，告诉您在OS X的菜单栏中(menu bar)或Windows的(Windows)系统托盘(system tray)中找到Duet 图标(Duet icon)。
如果单击该图标，它将要求您将设备连接到计算机。
此时，在 iPad 上打开Duet Display应用程序，然后将其连接到计算机。它应该会自动检测您的计算机并镜像屏幕。这是我的设置默认的样子。
在这里，我使用的是2009 年中期的旧款 MacBook Pro(MacBook Pro Mid-2009)和iPad 2，一切看起来都不错。iPad 上的所有东西都有点小，但那是因为它是较旧的iPad 2，而且我已经将它设置为镜像显示。如果单击菜单栏中(menu bar)的图标，您可以更改设置。
您会在顶部看到Extend Display ，然后是(Extend Display)Mirror Display、Framerate和Pixel Qualit y。如果您想将显示扩展到 iPad 而不仅仅是镜像它，请继续并选择以下四个选项之一：常规分辨率(Regular Resolution)、iPad Pro 分辨率(iPad Pro Resolution)、视网膜分辨率(Retina Resolution)或高分辨率(High Resolution)。
请注意，如果您使用的是iPad 2等较旧的 iPad ，您将无法选择常规分辨率(Regular Resolution)以外的任何内容。如果您有视网膜 iPad，则可以使用Retina或High 。iPad Pro选项显然仅适用于iPad Pro(Pros)。
我真正喜欢Duet Display的地方在于，第二个屏幕真的就像一个单独的第二个显示器。我的意思是，您可以将窗口从主屏幕拖到 iPad 上，并在每个屏幕上打开不同的应用程序。这是我的MacBook Pro上打开的(MacBook Pro and Maps)Chrome和iPad 上打开的地图的屏幕截图。
您会注意到 iPad 上有一个菜单栏和 Dock。真正酷的是你可以在 iPad 和主Mac上拥有多个桌面。当我的鼠标在iPad 屏幕上(iPad screen)时，我还可以使用所有正常的触控板手势在桌面之间滑动，而无需更改主Mac上的任何内容。
绝对使用像Air 或 Pro(Air or Pro)这样更高分辨率的 iPad会让一切看起来更好(lot nicer)。
我在Mac上没有遇到任何问题，但在我的Windows 笔记本电脑(Windows laptop)上确实遇到了一些问题。幸运的是，他们的客户支持(customer support)非常好，我在几个小时内就解决了这个问题。显然，我需要一个不同的视频驱动程序(video driver)，他们通过电子邮件发送给我，这解决了问题。
如果您打算将它与台式电脑(desktop computer)一起使用，您可能需要为自己购买一根 6 英尺的避雷线(lightning cable)和某种支架，以便您的 iPad 可以放在显示器旁边。
总体而言，如果您发现自己不经常使用 iPad，将其转换为第二台显示器是一个不错的选择，其成本远低于使用两台显示器的传统方法。如果您有任何问题，请发表评论。享受！
Use an iPad as a Second Monitor for PC or Mac
Do you happen to haνe an extra iPad laуing around the housе that you no longer use? I kеpt my iPad 2 for years before finally upgrading to the iPad Αir 2, which meant the iPad 2 just sat in a deѕk drawer. But why waste a perfectly good iPad, rіght?
I previously wrote about how you can setup dual monitors in Windows, but that requires a second monitor. Luckily, with some ingenious software, you can use your older iPads (2nd, 3rd, or 4th generation), iPad Airs (1 & 2), or iPad Pros as a second screen or second monitor to your Mac or Windows PC. This basically involves installing an app on your iPad and on your computer and then connecting the two directly using either a lightning cable or 30-pin cable (dock connector).
My favorite app and the only one I recommend is Duet Display. There are other options like Air Display and iDisplay, but both cost about the same and don’t work nearly as well. The direct connection between the computer and iPad make the experience virtually lag-free, which is very important when using a second screen. Trying to do this over WiFi (i.e. Air Display) was just painfully slow and not a good implementation.
Duet Display
It’s also worth noting that Duet Display was created by ex-Apple engineers and is probably one of the main reasons it works so well with iPads and Macs. The app costs $16, which is super-expensive when you look at the price of most apps in the App Store, but I would think of this more like a standard Windows or Mac program.
Getting everything setup is very straight-forward and doesn’t require any kind of account creation or anything like that. First, go ahead and download the app onto your iPad. Note that you can also use your iPhone as a second screen, but it was kind of useless in my tests. You definitely need a bigger screen in order to do any work properly.
Duet Display – iTunes
When you open the app, you’ll get some really simple instructions that tell you to go ahead and download the software on to your computer first.
Tap Got It and you’ll see a screen asking you to connect your iPad to your computer. Before we do that, however, we need to install the software on the PC or Mac first.
Go ahead and download the PC or Mac program onto your computer and install it. On the Mac, you’ll get a sleek rectangular install screen on startup.
Click the Start link, check I Agree and then click Authorize and Install on the next screen.
After the installation is complete, you’ll be asked to restart your computer. Go ahead and do that. Once you log back on, you should see a final screen telling you to find the Duet icon in the menu bar in OS X or the system tray in Windows.
If you click on the icon, it will ask you to connect your device to the computer.
At this point, open the Duet Display app on your iPad and then connect it to your computer. It should automatically detect your computer and mirror the screen. Here is what my setup looked like by default.
Here I am using an older MacBook Pro Mid-2009 with an iPad 2 and everything looked pretty good. Everything was a little small on the iPad, but that’s because it’s an older iPad 2 and because I had it setup to mirror the display. If you click on the icon in the menu bar, you can change the settings.
You’ll see Extend Display at the top, followed by Mirror Display, Framerate and Pixel Quality. If you want to extend the display to the iPad rather than just mirror it, go ahead and select one of the four options: Regular Resolution, iPad Pro Resolution, Retina Resolution, or High Resolution.
Note that you will not be able to select anything other than Regular Resolution if you are using an older iPad like the iPad 2. You can use Retina or High if you have a retina iPad. The iPad Pro option is obviously for only iPad Pros.
What I really liked about Duet Display is that the second screen really acts like a separate second monitor. What I mean is that you can drag windows from your main screen onto your iPad and have different apps open on each screen. Here’s a screenshot of Chrome open on my MacBook Pro and Maps open on the iPad.
You’ll notice that on the iPad there is a menu bar and also the dock. What’s really cool is that you can have multiple desktops on the iPad and on the main Mac. While my mouse is on the iPad screen, I can also use all the normal trackpad gestures to swipe between desktops without changing anything on the main Mac.
Definitely using a higher resolution iPad like the Air or Pro makes everything look a lot nicer.
I didn’t run into any trouble on my Mac, but I did run into some issues on my Windows laptop. Luckily, their customer support is excellent and I had the issue resolved in a matter of hours. Apparently, I needed a different video driver, which they emailed me, and that fixed the problem.
If you’re planning on using this with a desktop computer, you’ll probably need to buy yourself a 6-foot lightning cable and also some sort of stand so that your iPad can be placed right next to your monitor.
Overall, if you find yourself not using your iPad all that often, converting it into a second monitor is a great option that costs way less than the traditional method of using two monitors. If you have any questions, post a comment. Enjoy!
