use the following in oncreate
getWindow().addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
and use the permission
<uses-permission android:name="android.permission.WAKE_LOCK" >
</uses-permission>
<uses-permission android:name="android.permission.DISABLE_KEYGUARD" >
</uses-permission>