Service manual
Panorama® Service Manual 0070-10-0634 1 - 15
Instrument Description Theory of Operation
1.5.2 Touch Screen
The Touch Screen consists of a flat glass plate that fits over the face of a CRT or LCD monitor
display, and is an integral part of the monitor. The Touch Screen controller is located inside
the monitor housing. A DB-9 serial cable connects each monitor to the Serial Interface Card
or Serial Port on the Panorama Central Station. The Touch Screen uses surface acoustic wave
(SAW) technology.
1.5.2.1 Principles of Operation
Surface acoustic waves (SAW) are mechanical waves that propagate in the surface of the
medium in which they are generated. The actual detection and location of a finger touch on
a SAW Touch Screen depends on the absorption of a subsection of the Touch Screen’s SAW
energy by the finger touching the screen.
The Touch Screen creates an absence of SAW energy. SAW energy is coupled to and
extracted from the Touch Screen by four identical piezoelectric transducers and a nearly
invisible array of fired-on glass-fit acoustic reflector strips around the border of a glass panel.