bg_atualizados_android_tela (mdpi = px)

dpi_padroes_android:
320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800 hdpi,
etc).
480dp: a tweener tablet like the Streak (480x800 mdpi).
600dp: a 7” tablet (600x1024 mdpi).
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc).