Dontech Touch Screen Solutions

Dontech provides custom touch screen solutions for a variety of demanding military, avionic, medical and industrial applications including:
EMI/RFI Shielding via transparent conductive coatings and fine conductive grids (MEM100 and plated woven meshes
Expand thermal range via Therma Klear™ transparent heaters for low temperature operations
IR blocking filters to reduce thermal loading
Contrast enhancement (to improve sunlight readability) via AR, AG coatings and polarizers
Improved impact, shock and vibration via the addition chemically strengthened glass and optical bonding (IMO-bond™)
touch screen
touch screen
Touch screens are frequently used in conjunction with LCDs as data input devices in a variety of medical, industrial and military applications. Most commonly used touch screens include:
Resistive Touch Screens – most widely used due to cost and reliability. Typically constructed using layers of conductive polyester film and glass. Requires activation pressure to make physical contact between the conductive layers to generate an XY axis point. Inherent internal reflections may reduce high ambient light performance. Sunlight readability can be improved via antireflective coatings and layers of linear and circular polarizers to minimize internal reflections. Common configurations and include 4-, 5-, and 8-wire.
Surface Acoustic Wave – SAW uses ultrasonic waves that register where the touch is located. As a portion of the wave is absorbed, it sends a signal to the controller. Because it requires very low activation pressure, a SAW touch screen can be susceptible to surface contamination or damage.
Projective Capacitive Touch Screens – PCT is becoming increasingly popular due to its very high resolution. Projective capacitive technology relies on a capacitance change that occurs when touching near or on the sensor surface. A conductive grid is patterned on the glass surface and forms an XY array. Applying voltage to the array creates a grid of capacitors. The array is connected to a controller that converts analog to digital signals and locates the exact contact point. PCT’s excellent resolution enables multi-touch applications.
Infrared Touch Screens – operate using an array of infrared light emitting diodes (LEDs) and photo sensors to locate X and Y coordinates. The touch location is identified by the interruption of the IR beam. IR touch screens provide very good optical clarity and can accommodate very large displays. Resolution is dependent on spacing of the IR sensors; false activation can occur due to surface contamination. High ambient light that produces IR radiation may reduce the sensitivity of the IR sensors and, therefore, touch screen functionality.
Optical Imaging Touch Screens – a relatively new technology that uses optical sensors on the corners of the touch screen and infrared backlights to create a two-dimensional field. Touches are detected as shadows, and interpolation occurs to pinpoint the location of the field disruption. OI technology is scalable to large display sizes.
Enhanced Touch Screen / Display Assembly
touch screen
Touch screens used in demanding environments often require:
Linear or Circular Polarizers – reduce internal reflection to less than 2% by orienting reflected light to separate it from light emitted by the LCD.
Glass Front Resistive Touch Screens – to improve surface durability to abrasion and chemicals for touch screens used in rugged environments.
Chemically strengthened glass touch screens – to provide impact protection
EMI/RFI Shielding – using conductive coatings and optical, fine wire conductive grids
IR Blocking Filters – to reduce the thermal loading on liquid crystal displays (LCDs) or optical enclosures used in direct sunlight
Transparent Heaters – for low temperature operation and antifogging of touch screens
Antireflective coatings – applied to front and/or rear surface of touch screen to improve viewing in high ambient light
Optical bonding of the touch screen to LCD to improve sunlight readability and impact durability
touch screen
touch screen
Through industry partners, Dontech is able to offer standard and custom touch screen solutions from 2.8” to 47”. Touch screens can be enhanced with:
VARGard™ antireflective coatings
Linear and circular polarizers
Heat Shield™ IR blocking filters
Therma Klear™ transparent heaters
IMO-bond™ optical bonding
OFW and MEM100 optical conductive grids
VCF™ films for EMI/RFI shielding
touch screen
View our recent white papers on touch screen technology:
“EMI Shielding and Optical Enhancements to Touch Screens” – ITEM Interference Technology – Spring 2008 EMC Directory and Design Guide
“Enhancing Electronic Displays” – ECN – April 2008
“Shielding Touch Screens from EMI” – Electronic Products – May 2008
“Optical Enhancement and EMI Shielding for Touch Screens” – Information Display – May/June 2010