Article courtesy of Zytronic

Many of the factors that govern touchscreen design for outdoor use are concerned with the glass that protects the actual technology. However, the technology itself is also important in delivering lasting performance in all weathers.

There are multiple touchscreen technologies that all have their own strengths and weaknesses. However, some of those weaknesses are glaringly apparent when utilised in an outdoor environment. For that reason, it is important that manufacturers understand what each technology offers and how outdoor usage may affect your final product.

Resistive

Resistive touch screens have a pliable front layer and a solid rear layer separated by insulating dots; the inside surface of each layer is coated with a transparent conductive coating. Voltage applied to the layers produces a gradient across each layer. Pressing the flexible top sheet creates electrical contact between the resistive layers, essentially closing a switch in the circuit. Resistive technology offers manufacturers a cost-efficient touch panel.

Advantages: Resistive technology can be used with any input, from a stylus to a gloved hand. It is a low-cost technology and offers low power consumption. The system can be sealed for water resistance.

Weaknesses for Outdoor Use: While resistive sensors are inexpensive, the technology’s main disadvantage is its vulnerability to vandalism. The flexible front layer is susceptible to impact damage, scratches and even long-term wear. This makes the sensors unfit for use in unattended areas and outdoors. Worse still, the screen will cease functioning in any area of damage.

Infra-red

Infra-red (IR) touch technology is based on light-beam interruption: light emitting diodes on one side of the sensor, and light detectors on the opposite side, create an optical grid across the screen. The touch point is recognised when an object interrupts the beam of light.

Advantages: Can be used in very large displays and is a relatively low-cost technology. The display’s brightness and image clarity are not affected by the sensor.

Weaknesses for Outdoor Use: The light sensing technology required for using in IR touch sensors must be manufactured with large bezels, making sleek modern designs impossible, and creating the opportunity for dirt and water particles to gather along the edges of the sensor. This creates both problems for the responsiveness of the sensor, but also creates an uninviting platform to touch and interact with. Further still, sunlight, which contains IR rays, can interfere with the display and cause it to malfunction.

Surface Capacitive

Surface capacitive touch sensors (SCT) operate by placing a transparent electrode layer on top of a glass panel. When finger touches the monitor screen, it reacts to the electrical capacity of the human body; some of the electrical charge is transferred from the screen to the user and the touch is registered. This decrease in capacitance is detected by sensors located at the four corners of the screen, allowing the controller to determine the touch point.

Advantages: Superior image clarity when compared to resistance panels. It is unaffected by dirt or dust on its surface, which will be a significant factor outdoors.

Weaknesses for Outdoor Use: Designers choosing Surface capacitive sensors are extremely limited in the customisations and visual enhancements the technology can offer. Due to the construction of the sensors, custom printed borders or glass cut-outs are not possible, and like IR touch sensors, SCT sensors also require cumbersome bezels, which can collect dirt and water, interfering with the performance of the sensor. The sensor’s operation can be compromised by damage or liquids on the surface – which means rain on the screen can cause havoc for a user trying to interact with a product.

Projective Capacitive

Zytronic’s single/dual touch capable self-capacitive PCT™ technology is the ideal solution for outdoor use. Our technology detects and locates touch, senses a peak change in frequency and submits the data. When a user touches the screen, capacitance occurs between the finger and the sensor grid, whereupon the sensor’s electromagnetic field is disrupted. The peak change in frequency is measured, and by determining which row and column is closest to this peak change in frequency, the position of the user’s touch can be very accurately determined.

The sole disadvantage of this technology is that generally it can be more expensive than other formats. However, when specifying touchscreens for outdoor use – often in products that demand longevity and durability, compromising on cost and selecting a sub-par touch sensor will lead to inferior final products.

The Benefits of Projective Capacitive Touch

The benefits of this technology for outdoor use are extensive. The sensing technology is located behind a glass substrate, which can be toughened or strengthened according to your application – meaning your touchscreen will resist accidental impact and scratch damage.

We offer both single and multi-touch sensors that can be supplied with glass up to 10mm thick. This also means the screen is resistant to vandalism. The technology does offer custom printed borders, which can help seal the sensor and again protect against tampering.

Projective capacitive membranes work well in all weather and when wet, functioning even when users are wearing heavy gloves. ‘False’ (accidental) touches are also minimised due to the low resistance of our electrodes, giving users a responsive experience in all weathers. PCT screens are typically unaffected by dirt, grease or water – and can be set up bespoke to your requirements if there are concerns over other materials that may impact touch performance.

Outdoor use often coincides with large-scale displays. Whether it’s a banking terminal or a large digital signage product, Zytronic’s PCT touchscreens are available in sizes up to 100” diagonally that can detect touch through the thickest glass available. Due to the physical characteristics of how or touch technology is laid on the glass, PCT ensures a display’s brightness and image clarity remain good – aiding the final aesthetic impact of your project.

Offering a range of customisation options, a responsive touch experience in all conditions and the ability to utilise thick strengthened glass without compromising performance, Projective Capacitive Touchscreen technology is our suggested solution for outdoor use.