ZYTRONIC Displays, represented in Australia by JEA Technologies , has developed a touchscreen technology with outstanding potential for use in harsh environments.
Designed and manufactured by the UK-based company in state-of-the-art, ISO-approved manufacturing facilities, Zytronic's patented 'projected capacitive' Zytouch touch sensor technology is based on the principle of embedding microfine wires within a toughened laminate material.
Depending on the screen resolution and size, between 25 and 32 individual wires are deposited so as to effectively divide up the screen area into pixel-sized sensing cells.
A representation of the wire electrode X and Y array appears in the accompanying picture, which shows how pattern skew is used to ensure that optical fringing does not occur.
Each wire has a diameter of around one quarter of a human hair, meaning that they become invisible to the human eye when viewed against a powered display. The wires are connected to an integrated controller board, which establishes an oscillation frequency for each wire.
When a conducting stylus touches the glass surface of the sensor, a change in capacitance occurs. This results in a measurable oscillation frequency change in the wires surrounding the contact point.
The integrated controller then calculates the new capacitive values, this data is transferred to a host controller, and software is used to translate the sensor contact point to an absolute screen position.
Taking the above into consideration, Zytronic's Zytouch technology has a number of key advantages that made it an ideal choice for industrial applications:
* The screen can be operated by both bare and gloved fingers.
* The touch sensor itself is protected as it is embedded in a composite matrix.
* The Zytouch sensor is constructed from a combination of two plies of soda lime fully tempered glass with a total thickness of 7.8mm (3mm for the viewing face, and 4mm at the rear, and 0.8mm for the sensor layer). Because of this, the sensor is impervious to accidental and malicious damage, wear and tear and even severe scratching on the glass surface, or complete physical failure of the outer glass face of the sensor, will not prevent operation of the sensing technology.
* This method of touchscreen manufacture also ensures that no additional sealing is needed to prevent the sensor being affected by moisture and rain, solvents, harsh cleaning fluids, grease and dirt.
* Because the electric field generated by the microfine wires does not change with time or temperature, there is no possibility of sensor accuracy drifting with time.
* The Zytouch sensor can be placed behind a "protective/sacrificial" glass or polycarbonate layer up to 25mm thick and operate through that layer. This gives additional protection from all types of contaminants and can be used to seal of all the electronics from the environment. It also allows the surface to be very easily cleaned.
* Zytouch-based solutions help to minimise ongoing maintenance costs by eliminating the need for screen calibration during the screens operating lifetime.
Thanks to the microfine wires employed, Zytouch-based touchscreens deliver uncoated light transmission ratings of up to 88%, which is significantly higher than the transmission characteristics of conventional resistive and capacitive solutions.
Resolutions are below 1mm, and the positional accuracy of the sensor is rated at 1% error within the recommended viewing area. Response times of just 13ms are comparable with the best conventional technologies.
Zytronic also supply a range of optical and EMI filters that complement the Zytouch touchscreens.