Customized TFT displays for industry

11/22/2018 Know-How

Customized and modified TFT displays are becoming increasingly popular for industrial applications. Dominic Spirgat, Product Sales Manager Displays & Monitors at Rutronik, explains which adaptions are particularly popular and when these make good sense.

Industry displays can satisfy specific requirements depending on the site of application. Above and beyond this, design, ease of use and exclusivity - as users are accustomed to from smart phones and tablet PCs - are growing in importance. The most frequent customizations of industry displays include:

  • integration of touch
  • a longer flexfoil for connection
  • a brighter display
  • a specific interface
  • readability of the display even when exposed to sunlight
  • a large viewing angle or even legibility independent of the viewing angle

Together with the various display sizes, shapes, materials and back printing of the cover glass, e.g., with the customer's logo, industry displays are created which match the application and the customer's corporate identity perfectly.

An additional anti-glare coating helps to ensure the great readability of the TFT displays even when exposed to strong sunlight or bright lighting conditions. This matting surface coating is applied directly to the glass surface and provides the display with anti-glare properties.

At the top of the wish list: PCAP touch

The integration of PCAP (Projected CAPacitive) touch in the display is included on most customers' wish lists. With capacitive touch technology, the touch sensor is located below a glass or plastic surface which it penetrates in full. Whilst capacitive touchscreens can only be operated with the finger or using special styluses, they offer a number of advantages compared to resistive touchscreens.

  1. They enable multi-touch and gesture recognition.
  2. They also offer additional application protection, e.g. from vandalism, as toughened glass can be used.
  3. Integration of the display in the housing without dirt-collecting edges. As a result, the device can also be cleaned with aggressive disinfectants and cleaning agents without damaging the display or the entire application.
  4. This means smarter designs are possible.

Optical bonding

The cover glass of a PCAP touch display is connected to the touch sensor by means of optical bonding or a lamination process. Optical bonding refers to the full-surface bonding of two components. As such, not only are the cover glass and touch connected, but also the touch sensor and TFT panel - resulting in optical and mechanical benefits:

  • The display is easy to read even in sunlight as there is virtually no light refraction at the interfaces with the various materials.
  • The complete module is significantly more robust as, thanks to full-surface bonding, the display is similar to laminated glass.
  • There is no air gap between the touch sensor and cover glass as is sometimes the case when the touch and display are only adhered at the edge. With optical bonding no dust, other particles or condensation can damage the touch display.

However, a certain level of expertise is required for optical bonding. The adhesive must be highly transparent and should not suffer 'yellowing' through UV light exposure to ensure it does not affect the optical features of the device design in terms of display brightness and image contrast. Furthermore, air and material blemishes must be avoided during the bonding process and the bonding itself must balance any mechanical influences, e.g. various coefficients of expansion with temperature fluctuations as well as shock and vibration. As such, optical bonding remains a cost-intensive option.

Customized or standard industry display?

Display customization is not always the best option for every application, project or company. In many cases, standard industry displays offer better value for money. This depends, amongst other things, on the scale of the project. Adaption and the resulting tooling costs, approval and sampling processes do not make financial sense for every niche product - yet for very specific applications and those which demand an ideally adapted display which is not seen every day, they are the right choice. When multi-touch, gesture control, intuitive operation and special cover glass designs are required, there is no getting around customized displays. Rutronik supports and advises customers in every project phase, from the initial idea, tooling, and the approved samples to series production.

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