Motorola Droid razr has many smart features and one of those is that when you hold the smartphone to your ear during calls, your touchscreen sleeps to prevent accidental touches.
When you move Droid Razr away from your ear, the display lights up again.
You can use power button to make your touchscreen sleep or wake up. If you want to change the wait time before your droid razr goes to sleep you can update the settings .
Go to Menu > Settings > Display > Screen Timeout and Choose the timeout settings which best suits you.
Motorola Droid Razr’s touch screen is very sensitive and even a transparent screen guard covering the touch screen’s sensor can make your smartphone’s touchscreen to go to sleep. To avoid this, make sure that you use a screenguard doesn’t cover the sensor. Amazon has really good Droid Razr’s covers and screen guard which you use.