This recent problem with getting a blank screen when trying to update apps happened to me and this is how I fixed it on both my iPad2 and iPad mini:
1. Double click the home button to get the dock at the bottom of the screen
2. Hold your finger on the App Store icon in the dock until it wiggles
3. Touch the minus sign in the corner of the app store icon to delete the icon from the dock - This does not delete the app - just removes it from open status
4. Then go to the App Store icon on your home screen and update as you normally do and no more blank screen!
I'm not sure if this is the procedure that will need to be followed every time to update from now on or if Apple will fix this glitch that just started happening. In the past you didn't have to take the app off the active dock before updating normally but for some reason now it seems you do. But also when you don't have any apps to update it no longer tells you all apps are up to date but just gives a blank screen. Something changed and Apple needs to correct this.