At Bluestone we regularly fit many different types of touch screen to our monitors, typically we have wide experience of all the different touch screen technologies and are able to advise on the most suitable type for your particular application.
A brief overview of the commonly used touch technologies is as follows:-
These are the most commonly used type , they are cost effective and very reliable , they use a flexible polycarbonate overlay that deflects when touched and touches a conductively coated glass substrate , so they can sometimes be susceptible to mechanical damage to the overlay material. Available in 4 5 & 8 wire types and with USB and Serial interfaces. Special versions are available with toughened overlays and specialised sunlight viewable versions are available but they can be more expensive than standard ones. Not recommended where sharp implements are used by the operator or for areas where vandalism is a possibility. Easy to seal to IP 65 and IP67.
Basically these are solid glass screens with tiny wires embedded within it, they can be used to project through a protective window. They can be expensive in comparison to resistive types, but are very useful where an operator might be using cutting tools and knives or harsh chemicals. A typical application we have used them in is in a meat processing factory a public area where vandalism is a possibility or the University anatomy laboratory project where sharp tools are in use and the operator is liable to damage the screen with a tool. Projected capacitive screens are virtually impossible too wear out through normal use as they have no moving parts and can be made vandal proof. Easy to seal to IP 65/IP67
Surface Acoustic Wave
These touch screens are extremely clear as the screen is just a sheet of glass, the sensing element is done by means of small piezoelectric transducers mounted on the top surface of the screen , these transmit an acoustic sound signal across the surface of he screen a touch disturbs the sound waves and from this the touch position is calculated. A downside of this type of screen ids that the sensor prisms are mounted on the top surface of the glass and this can make mounting and sealing the screen more difficult.
We don’t recommend this technology in professional rugged applications, as it is not designed for use in metal cased monitors as it is prone to drift and is generally too inaccurate for professional use, as it requires frequent recalibration. Often used in gaming applications where accuracy is not a primary requirement.
Infra Red (IR)
We don’t recommend this particular technology in professional rugged applications, as it is not generally suitable due to its bulk and problems with sunlight interfering with the IR sensor element.