Always make the screen at the right
position when it is upside down by detecting ON/OFF signal through the tilt
sensor installed on the device.
Make the screen always at the right position
by detecting four different signals through the rotation sensor installed on
OncQue RBS350100 Optical Rotation detecting for 4 directions in vertical mode Senor
OncQue RBS311110 Photoelectric 45° Tilt Angle Sensor Switch