How do they work?

Touch-screen monitors have become more and more popular over the years as their price has steadily dropped in the last decade. There are two major systems used to interpret a persons’ touch. • Resistive • Capacitive An elemental touch-screen is made of three major constituents: the touch sensor, a controller and a software driver.

A touch-screen is an input device therefore, you need another device, such as a PC, to complete this input system triggered by tact.

1. The touch sensor The touch-screen sensor is a glass panel, which has a tactile responsive surface. This panel is placed over a screen so that the responsive piece cloaks a viewable area of the video screen There are several sensor technologies in the industry with diverse methods to detect the input. The sensor, for most systems, has an electrical current passes through it and palpating the screen causes a voltage alteration. This voltage alteration is exploited to determine the location of the tact to the screen.

2. Software driver Just like in any other PC component, the software driver program is installed so that the new component, in this case the touch screen, and the computer work together. This software communicates with the computer’s operating system and dictates how to interpret the touch sent to the computer from the controller. Most of these drivers are congruent to a mouse-emulation driver. So, in other words, touching your screen is like moving your mouse. This accredits your touch-screen to work with present software and accredits new applications to be developed without the need of specific programming of the touch-screen. Much equipment, for instance, thin client terminals, DVD players, and other specialized computer systems either don’t use software drivers or they have their own built-in touch-screen software driver.

3. Controller The controller is a small PC card that connects the PC and the touch sensitive glass panel. It captures information from the touch sensor and and converts it into information the PC can understand. The controller is usually found inside the monitor or inside plastic housing. You will need different classes of interfaces (connectors) depending on your screen.

The systems:

1. The resistive system consists of an ordinary glass panel with a conductive and a resistive layer, both layers fabricated from metal. Spacers separate these layers. When the system is operational, an electric current passes through both layers. Both layers make contact in the exact spot in which they are touched. This touch causes a variation in the electrical field, which is then perceived, and the computer calculates the coordinates of that point. When the coordinates are known, a driver translates them into information that the operating system can conceive. For a more detailed Four-wire system document Click Here for a more detailed five wire system document Click Here.

2. Capacitive system In this system, a layer, which stores an electrical charge, is installed on the glass panel of the monitor. As a user makes contact with his finger on the monitor, some of the electrical charge is transmitted to the user; therefore, the electrical charge on the capacitive layer diminishes. There are circuits located in each corner of the monitor, then the computer calculates, in relation to the distances of the circuits to the charge decrease, the point in which the touch occurred. This information is sent to the touch-screen driver software.  

Main Applications:

CRT and LCD Modules, PDA Devices, IA Products, Moblie Phones, Industrial Instrumentation, POS Informational
Kiosks,etc.