Displays are increasingly equipped with touch screen functionality. Think of control units, smartphones, or tablets. As every application asks for different features and performance requirements, Telerex offers a wide range of touch technologies including resistive, capacitive, infrared, SAW, and projected capacitive. In addition, Telerex offers client-specific touch screen solutions.
Touch screen technology
- IR (InfraRed)
- SAW (Surface Accoustic Wave)
- Projected Capacitive
Resistive touch technology is ideal for environments and applications where durability and robustness are important factors. Resistive touch technology is constructed out of two transparent layers, separated by a tiny air slot or by microdots. The top layer is slightly flexible and can be pressed either by using a finger or another object. The contact that is then made between the upper and lower layers is converted via a resistor into a precise electronic location. This technology is therefore suitable for use with fingers, gloves, pens or other pointing devices.
Resistive touch screens are resistant to dirt, grease, dust or liquids. It is a passive technology and therefore saves on power and is particularly suitable for portable devices. With 4-wire technology, both layers of the touch panel have a network of X and Y electrodes that make contact when operating the screen at a specific point. Standard screen sizes for 4-wire touch applications range from 6.4” to 19". With 5-wire technology, the entire network of X and Y electrodes is located in the lower layer, and the upper, flexible layer only serves as a touching point and voltage-probe. This makes the 5-wire touch technology even more resistant to rough handling, damage, or changes in temperature. With 5-wire touch panels available for LCD screens ranging from 10.4” to 19". Both types of technology can be controlled via RS-232 or USB.
Applications for resistive touch screen
- Vending machines
- Industrial power supplies
- Portable devices
- Point-of-sale areas
Resistive touch screen brands
- Leading Touch
Infrared touch screens are widely used in medical applications, kiosks, ticket and point-of-sale devices, and cash machines. The infrared touch frame, which can be mounted onto a display, includes on the edge an X and Y beam with infrared LEDs and in the opposite frame edges an X and Y beam with photo-electric receptors. Between the LEDs and receptors, an infrared grid is generated which becomes disrupted when touching the screen. This disturbance is located precisely by the electronics and is then translated into software commands.
Major advantages of infrared touchscreens are the 100% transmittance of the display light, suitability for all types of display media, and their very long service life. This technique also lends itself well to harsh working environments and is insensitive to scratches on the screen or to any changes in temperature. These infrared touchscreens are often used in industrial environments and for public applications.
Infrared Touch screen applications
- Outdoor and indoor kiosks
- Ticket machines
- Medical applications
- Industrial control units
- Large TFT or plasma screens
Surface Acoustic Wave Touchscreens
Surface acoustic wave technology uses ultrasonic waves that are sent over the surface of a touch panel. When the screen is touched, these waves are either partially or entirely absorbed. This supplies the control board with data and coordinates, from which the exact location of the touch point can be calculated. The controller also takes into account the presence of dirt, dust, drops, and calibrates itself automatically after these types of contamination are removed.
The controller is able to detect the stay time of dirt, dust and water drops, scratches, and other any imperfections; however, these are generated. Once an irregularity has been removed, the controller will be restored to its original pattern of average waveform.
Surface Acoustic Wave Touch Screen advantages
- Superior image clarity with high levels of light transmission
- Sensitive and rapid response
- Durable, resistant to deep scratches and abrasion
- Screen can be operated with fingers, gloves, leather, or a soft stylus
- Resistant to dirt and splashes
- Can be used by both consumers and SMEs